Author: Maddy

The Different Types Of Waves & How They Affect Us
There are different types of waves in this world. Every day, they affect us in one way or the other. But before we look at these different types of waves, we have to understand what a wave is.A wave is a vibration, oscillation or disturbance traveling through a medium which transfers energy from one particle in the medium to another but doesn’t displace the medium itself permanently.

Why is the study of waves important?

Waves are important to understand a variety of physical phenomena that happen around us everyday. From water waves to seismic (earthquake) waves that can cause a lot of destruction to life and property, from radio waves that form the basis of telecommunication to microwaves that help us cook food, from UV rays that can damage our skin to X-rays that have medical applications, they are everywhere.

Understanding the concept and functioning of waves can not only help us understand how various devices work, but also help us protect ourselves from the harmful effects of certain phenomena.

Types of waves

There are three major types of waves.

1.Mechanical waves

A mechanical wave is created by an oscillation or a disturbance (caused by a source) in an elastic medium (gas, liquid or solid). This disturbance causes a movement of the particles (which also gain energy) in the medium directly in contact with the source. These particles in turn transfer their energy to the nearby particles and so on. This leads to a transfer of energy and the propagation of the wave through the medium.

Example: A classical example is a stone falling into a pond or a lake. You can observe that ripples (waves) are created from the point where the stone falls into the water, moving outward. This is because, at the point where the stone touches the water, it displaces the water molecules that it directly comes in contact with. These water molecules gain energy, move and transfer the energy they gained to the nearby water molecules, which start moving. Then the nearby molecules do the same to the water molecules near them and so on. This movement of molecules creates a wave along the surface of the lake or pond.

To understand mechanical waves better, we should learn about the three types of mechanical waves and how they differ from each other.

Transverse waves

When the particles in the medium move in a direction perpendicular to the direction of movement of the wave, we call such a wave a Transverse wave.

Image credits

When you attach one end of a rope to an immovable object and move the other end of the rope up and down, the resulting wave is a transverse wave.

As you can see from the image below, while the wave is moving from left to right, the particles are just moving up and down. You can select a single particle to observe its motion.

Image credits

Examples – Vibrations in a guitar string, electromagnetic waves

Longitudinal waves

When the particles in the medium move in the same direction as the wave, the wave is called a longitudinal wave. Longitudinal waves always require a medium.

Image credits

If you attach one end of a slinky or a spring to a immovable object and push and pull the other end, the resulting wave is a longitudinal wave. In the image below, as you can see, the wave moves from left to right (the Compressions form the wave) and the particles oscillate from left to right and right to left.

Image credits

Example – Sound waves

Surface Waves

Surface waves are created when a disturbance occurs at the interface between two mediums.

Waves caused by wind on the surface of water (interface between air and water, 2 different mediums) is the most common example of surface waves. A surface wave is characterized by the circular motion of the particles in the medium and can be considered as a combination of both longitudinal and transverse waves.

Image credits

In the picture above, you can see that while the wave moves from left to right, the particles follow a circular path. At the top and bottom of the circle, the particle can be thought of moving left to right and right to left (longitudinal), whereas at the left and right side, it can be thought of moving from top to bottom and vice versa (transverse). This can also happen at the interface between 2 liquids like water and oil.

2. Electromagnetic waves

Produced by the vibration of charged particles, electromagnetic waves don’t need a medium for propagation. Therefore, they can travel through solid, liquid, gas and vacuum. Created by the interaction between electric and magnetic fields, electromagnetic waves can be further classified into different waves depending on the frequencies. They look like transverse waves (sine waves) and some of the properties of transverse waves apply to electromagnetic waves as well.

Example – X rays, UV rays, Infrared rays, visible light, etc.

You can read more about electromagnetic waves in our blog post here: 7 types of electromagnetic waves.

3. Matter waves

Till 1900 light was thought to be a combination of electromagnetic waves, whereas matter was thought of as a combination of localized particles. However, Albert Einstein proposed that light is made up of photons which can have both particle as well as wave nature.

In 1924, De Broglie proposed that similar to photons, electrons can also exhibit wave properties. Since then, it has been experimentally proven that electrons, neutral atoms and even molecules have wave-like properties.

Simply put, the wave produced by matter (like electrons, neutral atoms and molecules) is called matter wave.

Properties of a wave

Waves have some properties that define a wave.

Wavelength: Length between 2 consecutive maxima or minima

Frequency: Number of maxima or minima produced in one second

Amplitude: The magnitude of a maximum value or a minimum value

Crest: Maximum value in a transverse wave

Trough: Minimum value in a transverse wave

Compression: Most compressed part in a longitudinal wave

Rarefaction: Least compressed part in a longitudinal wave

Image credits

Facts you probably didn’t know
1. Both longitudinal and transverse waves can move through a solid. However, only longitudinal waves can travel through liquids and gases. That is how we know that the core of the earth is made of liquid (mostly molten iron). Earthquakes produce seismic waves that are both longitudinal and transverse waves. However, from the other side of the earth, a major part of the transverse waves couldn’t be detected, but most of the longitudinal waves were detected. Since transverse waves cannot move through liquids, it was deducted that the core of the earth is molten.
2. If it were not for electromagnetic waves, we would not have been alive now. Light waves, which are electromagnetic waves that don’t need a medium for propagation, from Sun made photosynthesis possible thereby creating complex life on earth.
3. The waves produced by throwing a stone into water and by blowing wind across its surface are not the same. While wind produces only surface waves along the surface, a stone thrown into water also produces (in addition to surface waves) longitudinal waves in its direction of movement, while moving to the bottom of the water body.
4. Electromagnetic waves travel at the speed of light.
5. Light travels faster than sound. That is why we see the lighting before we hear the thunder.
6. You cannot hear sounds in space because, there is no medium in space for the sound (longitudinal waves) to travel.
Did this blog post help you learn about the different types of waves?

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October 31, 2019
Interesting Facts About The Planets Of Our Solar System
This blog post lists some interesting facts about the planets of our solar system. The 8 planets in our solar system are listed in the ascending order of their distance from the Sun below.

Mercury

Mercury is a rocky planet made of a liquid metal core. The core constitutes 42% of the planet surrounded by a mantle made of silica and a solid outer crust.

Image by WikiImages from Pixabay

Venus

This planet is similar to the size and mass of our planet. However, it has a surface and atmosphere that differs from our planet considerably. Its atmosphere is extremely dense and made up of 96% Carbon dioxide and 3.5% Nitrogen.

Image by WikiImages from Pixabay

On the surface of venus, the air would be 90 times denser than that on earth. The atmospheric pressure would be equivalent to the pressure that is experienced while diving 3000 feet beneath the ocean. Due to the Green-house effect caused by Carbon dioxide, Venus is the hottest planet in our solar system. Its surface temperatures can rise up to 900°C.

Earth

Since we already know so much about the planet we live in, I skipped this section.

Mars

Mars has a rotational period and rotational axis similar to that of the Earth. Consequently, the days and seasons on Mars are similar to that of earth. It is nicknamed the `Red planet` of the solar system due to the presence of iron oxide on its surface.

Image by WikiImages from Pixa b ay

Mars’ atmosphere consists of almost 95% Carbo dioxide. Its atmospheric pressure is around 1% of earth’s atmospheric pressure. Therefore, liquid water cannot exist on the surface of Mars due to its low atmospheric pressure. However, its poles are covered with frozen water, which when melted can fill the surface with 11 meters of water. Mars also has 2 small moons.

Jupiter

Jupiter is one of the two gas giants in the solar system. It is composed of three-fourths of Hydrogen and almost one-fourth of Helium. Yet, its core is believed to be rocky.

Jupiter`s diameter is ten times smaller than that of the Sun, but eleven times bigger than that of the earth. Its outer atmosphere is home to several storms – the Great red spot, the biggest of these storms has been raging (at least) since the 17th century when it was first found and is almost twice as big as the earth. Jupiter also has 79 moons.

Europa

If you are looking for life in the solar system outside of earth, Europa may be your best bet. One of the biggest satellites of Jupiter, Europa is slightly smaller than our moon. However, it has all the three ingredients required to form and sustain life: liquid water, an energy source and the right organic compounds. It consists of an ice shell under which a thick layer of liquid water exists.

Saturn

The second biggest planet in our solar system and another gas giant, Saturn is also mostly made up of Hydrogen and Helium. It is famous for its rings which are formed by chunks of rock and ice. It has 62 moons. Saturn takes 10.7 hours to rotate once and 29 years to revolve around the Sun once.

Titan

The biggest moon of Saturn (which is bigger than Mercury), Titan, is the only moon in the solar system to have an atmosphere (made primarily of Nitrogen and Methane). This moon is believed to have the same conditions as early earth, since it is rich in hydrocarbons. It has liquid methane on its surface even though water and Oxygen are yet to be found.

Uranus

As the coldest planet in the solar system (-224°C), Uranus is one of the ice giants of the solar system. Although similar in composition to Jupiter and Saturn, Uranus has a layer of icy materials – water, methane and ammonia surrounding a small, rocky core. This methane is the reason for the Blue color of the Uranus. Uranus has 13 rings and 27 moons.

Image by WikiImages from Pixabay

Neptune

The only planet in the solar system not visible to the naked eye, Neptune can only be seen through a telescope. It is also known as an ice giant. Even though Uranus hits the coldest temperatures in some parts of the year, Neptune has the colder average temperature among all planets. It has 13 moons and 6 rings.

Image by WikiImages from Pixabay

Fun facts about the planets of our solar system
1. Venus is the only planets that rotates from East to West.
2. Uranus rotates on its sides, i.e., its poles are where the other planets have their equator.
3. One day on Mercury is 59 days long and one year is just 88 days long. Because of Mercury‘s elliptical orbit and sluggish rotation, the morning sun appears to rise briefly, set and then rise again in some parts of the planet. The same thing happens in reverse at sunset.
4. Neptune is the windiest world of the solar system, with winds of frozen methane traveling at 2000km/hr. The fastest winds on earth, however, hit only 400km/hr.
5. Neptune is the only planet in the solar system not visible to the naked eye.
Wait, Aren‘t there 9 planets in our solar system?

Until 1930, people believed there were only 8 planets in our solar system. However, with the discovery of Pluto on February 18, 1930, kids started learning about the nine planets of our solar system.

In the late 1990s, doubts about Pluto being a planet started to emerge.

The IAU definition of a full-fledged planet goes like this: A body that circles the sun without being some other object’s satellite, is large enough to be rounded by its own gravity (but not so big that it begins to undergo nuclear fusion, like a star) and has “cleared its neighborhood” of most other orbiting bodies.

Pluto, however, is not only small and has an offbeat orbit, but also shares its space with several asteroids in the Kuiper Belt, beyond Neptune.

Therefore, the International Astronomical Union declared Pluto as a “dwarf planet” in 2006. Thus the number of planets in our solar system was brought down to 8 once again.

We hope that these interesting facts about the planets of our solar system helped you learn about the solar system. If you liked this blog poast, you will like the following blog post too:
1. Types of satellite orbits
October 30, 2019
The Three Stages of Memory And How To Improve Them
This blog post will help you understand what the three stages of memory are, and how to improve each stage.We don’t need any explanation of what memory is. The Multi-store model (also known as modal or Atkinson-Shiffrin model), which is the most popular model on memory, describes memory as being a sequence of three stages.

According to this model, experts divide memory into sensory memory, short-term memory and long-term memory. Every piece of information entering your body moves through these three memories subsequently (conditions applicable).

The three stages of memory

1. Sensory memory

This is the shortest form of memory. It lasts for just 0.2s to 0.5s. It retains the information sensed through one or more of your senses (touch, sight, hearing, smell and taste) very briefly, but accurately.

If the brain senses that this exterior information is useful, then it makes this information last longer. Other types of memories then capture this information and store it for later use.

Sensory memory is essentially a buffer between all the information we perceive and the useful information that gets stored.

Example: When you look at something and close your eyes and still remember what you saw accurately for less than a second, it is sensory memory.

How can you improve your sensory memory?
1. Attention – The only way to train your sensory memory is by improving your attention. Attention is the process of concentrating on some aspects selectively while ignoring everything else, which helps in filtering the relevant stimuli from the irrelevant surroundings.
2. Quit multitasking – You may think multitasking is a boon, but it can divide your attention between several things thereby affecting your sensory memory.
Location
- The part of the brain responsible for sensory memory is the temporal lobe of the Cerebrum
2. Short-term memory (Working memory)

This is the place where the brain stores and processes information simultaneously. This part of the memory is important for the completion of several tasks.

The Short-term memory can store at most 5 to 9 items for a maximum of 10 to 15 seconds. But by using certain techniques, you can increase the number of items that your short-term memory can store. There are also techniques that help you increase the duration from 15 seconds to a minute.

Short-term memory is like a First-In-First-Out buffer. So, unless you take some conscious effort to retain older data, Short-term memory will erase older data to store newer data.

Examples:
1. While reading, your short-term memory stores the first part of the sentence till you finish reading the final part of that sentence. Otherwise, you won’t be able to understand the sentence.
2. While doing subtraction, your short-term memory stores the digits that are carried over.
3. In an argument, you may have to remember a point someone said, till he finishes talking so that you can counter it.
How can you improve your short-term memory?
1. Repetition/Rehearsal – This is the most common method for retaining information in your short-term memory longer. You can repeat the information in your mind again and again, so that the information reenters your short-term memory. This way, the short-term memory can retain the information for a longer time.
2. Chunking – Chunking is the process of grouping similar items together for better management. Each of these chunks can contain several similar items. But each chunk only represents just one of these 9 items you are trying to remember. (Do you remember that the short-term memory can store only a maximum of 9 items? If not, read the previous section called short-term memory once again). Therefore, the number of items that your short-term memory can store increases considerably.
3. Less distraction – The surroundings impact the quantity as well as the quality of the short-term memory considerably. Being in a calm environment can help you remember more items for a longer period of time.
4. Mnemonic strategies – The concept of linking a new data to a piece of information that we already know. More than any other technique, mnemonic strategies have shown to provide the best results to improve short-term memory.
5. Meditation – While meditating, the processing of information in the brain is not as active as it would be normally. Research doesn’t explain why it helps, but it does help.
6. Play brain games – Playing games like Sudoku and puzzles help you improve the processing speed of the short-term memory.
Location
October 30, 2019
How Does GPS work? Does It Need Internet To Work?
If you have always wondered, “How does GPS work? Does it need internet, or cell phone signal?”, this blog post will help you find out.

GPS:

GPS stands for Global Positioning System. It is a radio-navigation system consisting of 31 NAVSTAR GPS satellites orbiting at a height of 20,000 km from earth. If you remember what we learned about Satellites, you might know that GPS satellites orbit the earth in the medium-earth orbit with a semi-synchronous orbit.

These satellites are owned by USA and operated by the US Air Force. It is the process of finding a device’s (with a receiver) position on or near the surface of the earth withan accuracy of 30 cm (as of 2018). Satellites transmit radio signals (microwaves) at a frequency of 1575.42 MHz.

What are the three components of a GPS system?

The GPS system consists of a transmitter (GPS Satellite) that transmits the radio aves, a receiver (your phone) that receives the radio waves and evaluates the signals and a medium (air) through which it travels. Note that, since GPS uses microwaves (a type of electromagnetic waves), it doesn’t require a medium (gas, liquid or gas) for communication.

How does GPS work?

GPS works on the principle of trilateration. Watch this video from NASA that explains the concept of GPS and trilateration.

If you don’t want to watch the video, the same concept is explained below:

The concept is difficult to explain in 3D. So, let’s explore this in 2D. Take a look at the picture below.

Trilateration

Think of the Blue circle as the earth. Let’s say that you are standing on it at the point ‘1’. You have a cell phone with GPS (receiver) enabled and you want to find your position (to navigate to an address using Google Maps). Now, the Cell phone communicates with the satellite C, which returns the distance of the receiver from its location. Let’s draw a circle with that distance as radius and satellite C as center. Your phone (and you) can be anywhere on this Brown circle. It’s not enough to find your location though.

So, the receiver communicates with the next satellite (satellite B) and gets its distance from that satellite. So, now your phone knows its distance from these 2 satellites (B and C). It can be only in one of the 2 intersecting points ‘1’ or ‘2’, because the two circles, drawn using the distance of your phone from these satellites and these satellites as centers, meet only at these two points.

Now by knowing the distance of your phone from the third satellite, you can pinpoint the location of your phone to point ‘1’.

This concept is called Trilateration. By knowing the distance of a receiver from 3 satellites, its location in 2D can be calculated. Similarly, to find its location in 3D, 4 satellites are required. By having 24 GPS satellites, every location in earth can be tracked by 4 satellites at any given time. There are more than 5 spare satellites as well.

How does your phone differentiate between the signals from different satellites?

Each GPS satellite broadcasts a navigation message continuously at 50 bits/s. Broadcasting is a process in which a transmitter sends a message without a recipient address. All the receivers who are listening can receive this message. This navigation message consists of the following details and is 1500 bits long.

1. Time of week

2. Week number

3. Health report of the satellite (to find out if the satellite is malfunctioning)

This message is then encoded in a PRN code. All the GPS receivers know the PRN codes (sequence of zeroes and ones) of all the satellites. So, from the navigation message they receive, they can easily identify the satellite.

Facts you probably didn’t know:
1. A GPS signal doesn’t need an internet reception or telephonic reception.
2. GPS was invented due to the need for a global navigation system during the cold war and was used only for military purposes.
3. Soviet Union shot down a Korean passenger flight when it entered the Soviet airspace. This made the then American president to open the GPS for public use.
4. There are GPS shoes available, which is helpful in locating people with Alzheimer’s disease.
5. GPS can also be used to track time, since all the GPS satellites are equipped with atomic clocks.
6. If you are traveling at a height of 18,000 m faster than 1,900 km/h, your GPS device will deactivate itself so that it cannot be used as an intercontinental ballistic missile.
7. Even though US provides GPS services free of cost, US tax payers pay $3.9 million a day to keep it running.
8. Most people who have cars with GPS still use their phones for direction. – Source
9. If you use GPS a lot, beware. It reduces the ability of your brain to make mental maps as well as process spatial data. – Source
We hope that this blog post helped answer your question – “How does a GPS work?” If you liked this blog post, try our other science-related blog posts:
1. Harmful effects of electromagnetic radiation on humans
2. Planets of our solar system
October 29, 2019
The History Of Art – From The Stone Age Until Now
Read this blog post on the history of art. Find out how art has evolved over the years.Since time immemorial, humans have used art as a form of conveying ideas, emotions, hidden facts, and oppressed feelings. Studying the art (both paintings and sculptures) of a particular era can sometimes help understand the wider changes that took place in the society at that point in time and also understand the outlook of the artist.

Based on its year of creation, a piece of art or architecture can be classified as follows:

Stone age art (2,500,00 BC – 3000 BC)

Stone age art can be classified into Mesolithic art (10,000 BC – 4000 BC) and Neolithic art (4000 BC – 2000 BC).

The paintings that were found before Mesolithic age are mostly cave paintings. These were mostly abstract or symbolic paintings. For example, the cave painting that can be found in Altamira cave, Spain was dated to be between 13,000 and 35,000 years old.

Cave Painting in Altamira

Mesolithic art (10,000 BC – 4000 BC)

Mesolithic art age began with the change in climate and an improvement in living conditions, which led to humans moving out of caves and living on outdoor sites. Hence, in the Mesolithic age, humans started to paint more on outdoor sites than caves.

Several paintings found from this era are human figures and the paintings started to become more narrative. This is also the era where 3D-art in the form of sculptures started to be carved. Decorative drawings on objects like Pots also started to emerge during this period.

Dance of Cogul (Mesolithic) painting, Spain & the Mesolithic sculpture, Serbia

One of the greatest works from this era is the “Thinker from Cernavado”.

The Thinker of Cernavoda

Neolithic art (4000 BC – 2000 BC)

Due to the increased settlements and origin of civilizations, Neolithic age gave birth to crafts. Therefore, in the Neolithic age, due to the development in pottery and weaving, ornamentation and decoration attained more focus. It is during this period that calligraphy was invented in China.

Primitive jewelry emerged during this era. This is not to say that art was completely ignored. Indeed art in the form of bronze statues and large-stone structures (megaliths, passage tombs and pyramids) became famous during this era. One of these famous large-stone structures is the Stonehenge, England.

However, ceramic pottery was the major medium of Neolithic art.

Stonehenge, England

Bronze age art (3000 BC – 1200 BC)

Due to the emergence of cities, and the creation of more sophisticated tools, the bronze age gave rise to a wide range of monumental artworks. Some of the famous arts during this era include

Egyptian art

Burial chambers called pyramids and wax paintings were the masterpieces of the Egyptian art.

Egyptian painting

Persian art

Persian art was well-known for the ceramic paintings, carpets, silk weaving and rock sculptures.

Sumerian art

Sumerian art is famous for the stepped pyramids called Ziggurats built from clay bricks and decorated with colored glazes.

Ziggurat

Minoan art

Minoan art often featured marine as well as mythological animals on stone, ceramics and vases.

Picture credits – https://www.flickr.com/photos/cavorite/98591365/in/album-1011009/

Iron age art (1500 BC – 350 BC)

Due to the discovery of iron and the creation of iron tools of different shapes and sizes, metalwork as an art form started to flourish during this period. Only few secure cities existed during this era. Therefore, art was mostly limited to adornments on personal items, vessels, weapons and boats. Some of the famous arts of this era are:

Greek art

Greek art went through different ages maturing from paintings on pots and vases to paintings of important military and political successes to the construction of huge structures, which gave rise to some of the wonders of the ancient world.

Etruscan art

Etruscan art was famous for their tomb or funerary paintings.

Picture credits

Celtic art

Metalwork was the major form of Celtic artwork.

Roman art

Romans adapted the Greek art style to create paintings to glorify Rome`s power and build grandiose monuments to entertain their population.

Medieval art (350 BC – 1300 AD)

With the death of the Roman emperor Theodosius in 395 AD, Rome was split into two halves and Christianity became the official religion of the empire. Due to these advancements, medieval art was mostly themed around Christianity and Bible. Some of the noteworthy art styles of this era include:

Byzantine art

Almost entirely religious (Christianity), Byzantine art focused more on 2D-paintings in churches rather than 3D-sculptures.

Early Irish Christian art

Ornate manuscripts and religious metalwork, including crosses decorated with scenes of Bible were the iconic artworks of the Early Irish Christian art.

Romanesque art

Illuminated Christian texts depicted to the world, the beauty of the Romanesque art.

Byzantine art By Dianelos Georgoudis – Own work, CC BY-SA 3.0 & Gothic art By MOSSOT – Own work, CC BY-SA 3.0,

Gothic art

Stained glass art in cathedrals to tell the illiterate masses about the stories in the Bible are the masterpieces of Gothic art. Some famous examples include Notre Dame in Paris, the Cologne Cathedral and St Stephen`s cathedral in Vienna.

The Renaissance (1300 AD – 1620 AD)

While the Medieval art focused mostly on religious aspects, the Renaissance, centered on Italy, was the reestablishing of fine art painting and architecture based on the principles of Iron age Greek art.

Renaissance (1300 AD – 1620 AD)

Renaissance was built upon the idea of “Humanism”, which downplayed the religious domination of art to create art that was based on the dignity and worth of the individual. This was possible because of rich Italian families who started patronizing artists and funding them. Due to this new financial support, artists started rejecting the emphasis on religion (focus of medieval art) and started focusing more on the human aspect of life.

During this era, in northern Europe, oils started to be used for painting. Printmaking also gained popularity with the invention of printing press.

MonaLisa

Mannerism (1525 AD -1600 AD)

Another form of art, called Mannerism (1525 AD -1600 AD), also developed during the end of this era as a response to Renaissance. It was more artificial and intellectual whereas Renaissance was more naturalistic.

Elongated human figures with varied emotions and strained poses, unusual variation in lighting (to create depth), scale, color or perspective are common attributes of art based on Mannerism.

Head of the Madonna

Post Renaissance art (1600 AD – 1850 AD)

During this era, several types of art flourished in the following chronological order:

Baroque art (1600 AD – 1700 AD)

The Baroque is a highly extravagant style of art and architecture employed mostly by the churches to attract the masses.

The main characteristics of Baroque art was the heavy use of the primary colors (Yellow, Red and Blue), light and darkness to bring focus to the central figures.

By Nicolas Poussin, Public Domain

Another main characteristic of Baroque architecture is the dome that had lavishly decorated paintings of angels and saints. This gave the impression of those looking from below as though they were looking up at heaven. Baroque paintings mostly brought back heroic moments in history back to life with the main motto being emotion, movement and drama.

Rococo art (1700 AD – 1789 AD)

Rococo art’s main motto was to create a sense of awe and inspiration which was achieved not only by the simple exteriors and extravagant, theatrical interiors, but also by the use of curves, counter-curves and other elements modeled on nature.

Paintings were often integrated with carved, painted woodwork and gilded Bronze. Looking at the illusionist ceiling paintings often gave the impression that the figures on the dome were looking down at the people below.

Interior of Santi Giovanni e Paolo (Venice) – The Glory of St. Dominic by PiazzettaBy Didier Descouens – Own work, Public Domain

Neoclassical art (1790 AD – 1830 AD)

Born as the response to the famous Rococo art, Neoclassical art is characterized by the renewed attachment to Greek and Roman mythology, paintings of heroic nude male, dramatic lighting and the use of White, Red and Gold colors.

David, 1801. Napoleon Crossing The Alps.

The Romanticism movement (1790 AD – 1830 AD)

In stark contrast to Neoclassical art that focused on the intellectual and universal values (like heroism), Romanticism focused more on senses and emotions and glorified the past and nature.

The Desperate Man by Gustav Courbert

Realism

Realism is the art of depicting subject matter without adding any superficial elements like extra colors, supernatural elements, etc. It is also called Naturalism.

Due to the 1848 revolution, not just royal people, exaggerated emotions and supernatural elements, but also average, working class people and day-to-day happenings that happened in the present were seen as art-worthy subjects. This gave rise to Realism in the 1850s.

By Gustave Courbet – 1. The Yorck Project (2002) 10.000 Meisterwerke der Malerei (DVD-ROM), distributed by DIRECTMEDIA Publishing GmbH. ISBN: 3936122202.2./3. Musée Fabre, Official gallery link4. Freunde der Nationalgalerie, Staatliche Museen zu Berlin, P

Modern art (1860s – 1970s)

The advent of industrial revolution changed the way people lived and traveled. This gave rise to crowded urban areas (market places and commuting areas), which where very good places for artists to showcase their talents.

Emergence of these crowded urban areas and social changes inspired artists to try new themes, thereby giving birth to a dozen types of art. The following are the most noteworthy among these art types.

Impressionism

Characterized by loose brushwork and non-naturalist colors, most of the works of impressionism were landscapes. Many impressionist paintings will be unrecognizable, if looked close-up.

Impressionism painting by Claude Monet

Fauvism

Fauvism is very similar to Impressionism in the way the paintings were made. It, however, made use of extravagant and varied colors that made Impressionist paintings look simple.

Fauvism painting by Henri Mantesse

Cubism

Contrary to other methods of painting where lines were used to create images, flat planes were used in Cubism to create images and convey messages.

Cubism painting

Futurism

Futurism glorified future technologies like machinery, airplanes and other scientific achievements.

Picture credits

Expressionism

The main goal was to convey emotion rather than depict reality. Distorted objects and vivid, shocking colors are used to achieve the same.

Expressionism painting – The Scream, by Edvard Munch

Contemporary art (1970 AD – present)

In this era, the focus has shifted from the artwork itself to the message it conveys and how the artist conveys it. Hence, several medias like graffiti, video, etc have come into play.

Contemporary art

Fun facts you probably didn’t know
1. Stone age humans created paintings and sculptures not for entertainment, but only because they thought that these paintings and sculptures have supernatural powers.
2. Religion played a major part of daily life during the Medieval Ages, reasons why the artists of the early Medieval Ages were predominantly priests and monks who lived in monasteries.
3. Anatomy was another interest to Renaissance artists. Artists worked with scientist in dissecting the human body to help them with proportions so that they could better themselves in depicting the true image of a human.
4. There was a sculpture so small, its artist accidentally inhaled it.
We hope that this blog post on the history of art helped you understand how art has evolved over the years. If you liked this blog post, you will like the following blog post too:
1. The best painters of all time
October 28, 2019
The Worst Epidemics in History That Everyone Should Know

Even though wars and natural catastrophes had claimed millions of lives, both humans and animals, throughout the history of life on earth, some epidemics have completely wiped out human populations in some countries. This blog post looks at some of these worst epidemics in history.

Thanks to the improvement in medical field and hygiene, we can afford to live carefree without worrying about the occurrence of another such devastating epidemic in our neighborhood. But, it has not always been the case.

Endemic, Epidemic and Pandemic

An Endemic is a disease that exists in a specific region or population permanently. An Epidemic is an infectious disease that rapidly spreads across a huge community or population within a short period of time (within 2 weeks usually). A Pandemic is an epidemic that has spread throughout the world.

Several diseases appear harmless now due to the development of medical science. However, even the thought of these diseases horrified humans at a point in time. This article will discuss some of the worst epidemics in history based on the impact they had on the world’s population.

Worst epidemics in history

1. Plague of Justinian (541 AD – 542 AD)

Plague is a disease caused by Bacteria. It is found mainly in rodents (rats mainly) and the fleas which feed on these rodents. While some forms of Plague are transmitted to humans mainly through rodent or flea bites and are non-contagious, others are contagious spreading from humans to humans as well.

via GIPHY

Which countries were affected?

One of the worst epidemics in history, the Plague of Justinian was named after Justinian The Great, the emperor of the Byzantine (East Rome) empire. The Byzantine Empire was the most affected empire because of the outbreak. It includes several present-day countries in Asia, Europe, and Africa (Greece, Turkey, Syria, Lebanon, Israel, Jordan, most Baltic states, and Egypt). The emperor himself contracted the disease but survived.

Where did it originate and how did it spread?

The Byzantine empire depended heavily on Egypt, for the supply of grains to feed its huge population. The disease might have been transmitted by the rats which were in the ships that carried these grains from Egypt. Modern investigations show that this Bacteria might have originated in China or India originally and might have been transmitted to Egypt because of trade, from where it spread to the Byzantine Empire.

How many people did it kill?

At its peak, the disease was killing 5,000 – 10,000 people a day. By 750 AD, when the disease vanished completely from Europe, it has already killed 50 to 100 million people. It erased 13% – 26% of the human population (at the time of its outbreak) from the face of the earth. During the time of Justinian, there wasn’t enough place to bury the dead, So, the c orpses littered the streets, making the entire city smell like the dead.

Symptoms and death

According to historical records, people contracted with the disease showed symptoms like fever, headache, abdominal pain, etc. Some of these people then suffered from delusions, nightmares, and comas while others died almost immediately after showing these symptoms. These historical records, however, are not proven to be accurate.

How did the Plague of Justinian vanish?

Nobody knows exactly why, but the bacteria that caused the Plague of Justinian evolved itself into extinction. It probably evolved into a species that couldn’t survive and died out or into a species that wasn’t lethal.

What would happen if it occurred now?

The Plague of Justinian cannot reoccur today, because its traces have completely vanished.

2. Black Death (1347 AD – 1351 AD)

Also known as the Black Plague or the Great Plague, this epidemic reoccurred several times in history. This is widely considered the worst epidemic in history. The last occurrence of this plague was in the 19^th century. It is a type of Bubonic Plague that spreads from rodents to humans but not from humans to humans.

via GIPHY

Which countries were affected?

Many countries in Asia and Europe were severely affected. Europe lost somewhere between 30% – 60% of its population to the plague. In the 14^th century, the plague reduced the population of the world from 475 million to 350 – 375 million. It took 200 years for the world to recover its lost population.

Where did it originate and how did it spread?

The disease is believed to have originated in Asia (mostly China). Due to the climate change in Asia, the grasslands died out. So, the rodents fled to more fertile lands spreading the disease. The traders traveling through the Silk route brought the disease to Russia, from where it traveled by trade ships to Europe. Armies with infected soldiers attacking other countries spread the disease. Famines and lack of hygiene catapulted the disease into an epidemic.

How many people did it kill?

In the three times the Dark Plague hit (Outbreak -14^th century, Second plague pandemic -14^th to 17^th century, Third plague pandemic -19^th century), somewhere between 75 to 200 million people died.

Symptoms and death

The most common symptoms were the occurrence of tumors (as big as an apple) in armpits and groins. This was then followed by fever and vomiting of blood. 80% of these victims died within the next 2 to 7 days.

How did the Black death vanish?

The Black Death was exterminated not by humans or medical science, but by 2 rules of nature.

1. Nature of the plague – Black Death is a deadly epidemic that killed 80% of its victims. A pathogen (harmful microorganism) that kills its victims cannot survive for long, because it eventually runs out of victims thereby causing its own extinction.

2. Evolution – Since Black Death existed long enough, some of the humans started developing resistance to it, due to mutation (change in DNA). The disease had a higher success rate of killing people without the mutation than people with this mutation. This led to future generations of humans who had more resistance to the disease.

What would happen if it occurred now?

Unlike its cousin ‘Plague of Justinian’, the ‘Black Death’ still survives, killing someone or the other somewhere. However, it is not as deadly as before because we have antibiotics now and antibiotics are very effective against the plague. In addition to that, huge cities, where the epidemic is likely to emerge, have controlled rat populations, and improved hygiene.

3. AIDS (1959 AD – present)

The Acquired Immune Deficiency Syndrome (AIDS) caused by the Human Immunodeficiency Virus (HIV) is one of the worst epidemics in history, that humanity has ever seen.

Which countries are affected?

Africa is the continent worst affected by AIDS. Almost two-thirds of all the people infected by HIV live in Africa. In two of those countries, more than one-fourth of the population is infected by HIV. The main reasons for AIDS being prevalent in these parts of the world are sex-based violence, lack of proper information about the disease, and lack of proper medical care.

Where did it originate and how did it spread?

The source of HIV is a species of Chimpanzee prevalent in West Africa. Several decades ago, when hunters hunted these Chimpanzees for food, they might have contracted the Chimpanzee version of HIV. This virus could have later undergone mutation to become HIV that affects humans. This later spread to other parts of Africa. The earliest occurrence of AIDS was in Congo in 1959.

How many people did it kill?

Approximately 39 million people have died because of HIV and an additional 36.9 million people are still living with HIV.

HIV might not have killed as many people as the Plague of Justinian or the Black Plague. But it has killed so many people in the modern era when there are no large-scale wars and when the medical field is so advanced. (In my opinion) Had it occurred several centuries ago when large scale wars, unprotected sex, and other epidemics were so prevalent, it could have killed several times as many people.

Symptoms and death

HIV weakens your immune system to a point where it cannot fight against common germs. This makes the victim more prone to other types of infections (specifically cancers and tumors) and diseases that can be deadlier than normal. But HIV can survive 10 years in the victim’s body without showing any symptoms. During this time, it kills the proteins in the body while making a copy of itself.

HIV can be transmitted through sex, blood, childbirth or through breastfeeding.

How has the medical field helped the victims?

While the medical field couldn’t find a cure for AIDS till now, it has definitely helped increase the life longevity of the victims. When identified at an early stage, the medications can help a 20-year A IDS victim live another 46 years. This is an impressive medical feat.

via GIPHY

The problem, however, is that most people don’t realize they have HIV until the last stage. In addition to that, even though these medications certainly help the people in the West, the majority of people in Africa don’t have the financial means to avail these medications.

Prevention

Using condoms, using disposable syringes and increasing the awareness about the disease can help prevent AIDS.

4. Spanish flu (1918 AD – 1920 AD)

Also known as the 1918 Influenza pandemic, the Spanish flu is one of the worst epidemics in history to have attacked mankind. The Spanish flu virus is notorious (when compared to other influenza viruses) for its ability to reproduce itself (up to 39,000 more) and its lethality (up to 100 times more).

Which countries were affected?

The Spanish flu was a pandemic. A pandemic is an epidemic that has spread throughout the world. So, different countries around the world were affected. Due to the first world war, occurrences of the 1918 Influenza pandemic in the fighting nations like the USA, Germany, UK were not reported (accurately) so as to not affect the morale of the soldiers. However, in Spain, a neutral nation, the incidents (including the king contracting the disease) were reported. Therefore, the 1918 Influenza pandemic also came to be known as the Spanish flu.

Where did it originate and how did it spread?

The Spanish flu might have originated in France or in USA. A cough or sneeze of an infected person can release hundreds of thousands of these viruses which spread the flu to those nearby. Wartime mobilization of troops meant that the disease can spread faster and travel farther.

via GIPHY

How many people did it kill?

About one-third of the world’s population was infected by the Spanish flu and 10% -20% (50 – 100 million people) died because of it. 99% of the people who died were less than 65 years old. Normally, Influenza kills the very young and the very old. However, the Spanish flu also killed very healthy adults (aged 20 – 40). This was both a unique and scary feature of this influenza.

Why did so many young adults die?

This was probably due to the Russian flu (caused by Group 2 Influenza virus) that killed around 1 million people during 1889 – 1890. Normally, people who contract the flu at one point in their life become resilient to the same or similar type of flu virus. So, kids born during this time had increased resilience to Group 2 virus. However, this could have caused these kids to become more susceptible to Spanish Flu which was caused due to a Group 1 Influenza virus.

Symptoms and death

Symptoms included fever, body pain, and diarrhea. Patients would then suffer from lack of oxygen as a bloody, frothy substance filled the lungs leading to death.

How did the Spanish flu vanish?

The Spanish flu could have evolved itself into a less lethal one, because it runs out of victims, if it kills all its victims. The doctors might have also gotten better at treating the disease.

What would happen if it occurred now?

In 1918, the Spanish flu was so effective not just because of the nature of the virus, but also because of the time when it occurred. It occurred at the time of the first world war. Mobilizing troops meant groups of people crowded in closed areas, which helped influenza spread faster.

In addition to that, healthcare services were limited and the medical technology was not as advanced as today. Isolation of victims and supportive care were the only options available at that time. Hence one of the worst epidemics in history killed so many people.

Today, the world is better prepared for such epidemics because of advancements in the fields of disease surveillance, medical technology, vaccines, and pandemic planning. Besides, WHO has a dedicated organization that monitors changes in flu viruses and also looks for new flu viruses.

Should a new influenza pandemic attack us, we would have a vaccine against it in 20 weeks. However, due to the current human population, we would fall short on the number of vaccines we can mass-produce and their cost would mean that several poor countries would not be able to afford them.

We hope that this blog post on the worst epidemics in history helped you understand about epidemics and the damage they caused to the human society.

October 27, 2019
Parts Of The Human Brain And Their Functions
This blog post will help you learn about the different parts of the human brain and their functions. The brain is arguably the most important part of our body. It is the control center of the body. It is also the place where all the information, like memories, skills and emotions, related to our survival are stored.

The sperm whale has the biggest brain among mammals. But the human brain has the highest number of neurons, which store and transmit information as signals.

Parts of the brain and their functions

In order to lead a healthy life, maintaining a good mental health is indispensable. Therefore, learning about the different parts of the brain and their functions becomes important.

The closer a part of the brain is to the spinal cord, the more basic the functions it performs.

Brainstem

Location

This part of the brain is like the stem of a plant. It connects the brain to the spinal cord in the same way the stem connects the leaves to the roots.

Function

The functions this part of the brain performs are very basic. It controls several voluntary and involuntary functions like breathing, digestion, heartbeat etc. It can be further divided into Midbrain, Pons and Medula Oblangata.

Damage

Damage to the Brainstem can cause speech impairment, memory loss, loss of consciousness, coma, paralysis and stroke.

Prevention

Traffic accidents are the main cause of damage to the Brainstem. So, wearing helmets and seat-belts can reduce the risk of injury.

Cerebellum

Location

The Cerebellum is located at the back of our brain (on the opposite side of the Brainstem). It contributes to only 10% of the weight of the brain. Yet, it contains half of all the neurons in our brain.

Function

Cerebellum receives information from the nervous system, spinal cord and other parts of the brain and regulates body movements. It is also responsible for maintaining equilibrium, balance, coordination and learning motor behaviors like cycling, swimming, walking, etc.

Damage

D amage to Cerebellum can cause problems in juding distances properly and make you fall easily. It can also lead to weak muscles, slurred speech, difficulty/inability in performing fast alternate movements, headaches and stroke.

Prevention

Quitting smoking, reducing alcohol intake, exercising regularly, avoiding the handling of Lead and using protective head gears.

Thalamus

Location

This part of the brain is located just above the Brainstem and Cerebellum.

Function

The main functions of the Thalamus are relaying sensor signals to the Cerebrum and regulation of sleep, consciousness and alertness. Just below the Thalamus, we can find the Hypothalamus which is responsible for regulating body temperature.

Below the Hypothalamus the Pituitary gland is located. It secretes the Hormones that control growth, blood pressure, metabolism and the functions of sex organs, thyroid glands etc.

Damage

Damage to any part of Thalamus could lead primarily to sensory confusion. For example, Audio sensory information (from your ears) could be wrongly sent to visual information processing center or vice versa. It can lead to reduced pain sensation and loss in sensation in one side of the body. It can also cause difficulties in finding words, memory and attention disorders, apathy, and inability to stop a thought from occurring. In some cases, it also leads to coma.

Damage to Pituitary gland can cause the Pituitary gland to stop producing one or more of its hormones. It might lead to reduced/excessive growth, reduced sex drive, weight gain and delaying or absence of puberty.

Prevention

While brain injuries can also damage the Thalamus, the primary reasons are malnutrition, eating- and genetic-disorders. A diet rich in omega-3 fatty acids (but contains less saturated fats), Vitamin B and Vitamin C can keep the Thalamus healthy.

The main cause of damage to Pituitary gland are Pituitary tumors (non-cancerous). Drinking at least 4-6 cups of water a day and reducing stress can help keep your Pituitary gland healthy. Eating a well-balanced diet (rich in fruits and vegetables, omega-3 fatty acids), and reducing Sodium intake are also important.

Cerebrum

Location

The Cerebrum is the largest part of our brain. It contains the cerebral cortex that can be further divided into right and left hemispheres.

Function

This part of the brain is responsible for everything that differentiates us from animals. It controls our decision-making abilities, thought process, memory, senses, speech and emotional response.

The Cerebrum can be further divided into the Frontal lobe, the Parietal lobe, the Occipital lobe and the Temporal lobe. The Frontal lobe is located just behind our forehead. It is responsible for reasoning, planning, problem-solving, our emotions, our social and sexual behaviors. In the mid section, the Parietal lobe is located, which is responsible for movement, orientation and perception of stimuli. At the back side, we have the Occipital lobe where visual processing takes place. On both sides, we have the Temporal lobe which is responsible for audio processing, speech and memory.

Damage

Damage to Cerebrum can cause several problems.

A Frontal lobe injury can cause personality, mood and behavioral changes; problems in focusing and problem-solving; difficulty in interacting.

A damaged Parietal lobe may cause problems in reading, drawing and hand-eye coordination; differentiating right and left; doing Mathematics.

An Occipital lobe injury may cause problems in reading, writing, distinguishing colors, locating objects, and cause visual hallucinations.

Damage to the Temporal lobe can cause auditory hallucinations, short-term memory loss, and aggressive behavior. It can also make recognizing faces difficult.

Prevention

Cerebral damage may occur during childbirth (Cerebral Palsy). It can also occur at a later point in life due to Stroke or Dementia. Moreover, traffic accidents, sports injuries, violence, and falling (Traumatic head injury) can also cause cerebral damage. So, to protect your child from Cerebral Palsy, get vaccinated before childbirth, and avoid using alcohol, tobacco and drugs. Also use protective headgear for your children when you think their safety could be compromised.

Eating a well-balanced diet and exercising for 30 minutes a day can help prevent a Stroke. As for traumatic head injuries, being careful and using protective head-gears can certainly reduce the probability of damage to the cerebrum. According to a research, running increased the lifespan of mice with cerebral damage from 40 days to about 365 days. So, exercising can certainly help keep your Cerebrum healthy.

Safety system

Our brains have several layers of defenses to protect them from external damage. The outermost layer is our skull. Inside the skull, the brain is further protected by sturdy membranes called Meninges. Inside the meninges, the brain lies in a layer of fluid to further cushion it from damage.

Fun facts that you probably didn’t know
1. The right hemisphere of the frontal lobe controls the left part of the body, and vice versa.
2. Your brain is almost 75% water. That’s why dehydration impacts the functions of your brain negatively.
3. The brain contributes to only 2% to your body’s mass. Yet, it consumes 25% of all the energy and uses 20% of the Oxygen and blood in your body.
4. Cholesterol is indispensable for learning and memory. Indeed, 25% of all the cholesterol inside your body is in your brain. However, depending on age and several other factors, high Cholesterol can have negative effects.
5. 7-9 hours of sleep is recommended for your brain and body to heal and function properly. Sleep deprivation can kill brain cells impacting cognition, judgment and reaction time negatively.
6. Men’s brains are typically 10% larger than women’s. However, the Hippocampus (located in the Temporal lobe), which is mostly responsible for memory, is larger in women.
7. Technology impacts your brain negatively. The average attention span has dropped from 12s in 2000 to 8s as of now. Even a goldfish has a higher attention span of 9s.
8. Relying on GPS negatively impacts your innate sense of direction, that took thousands of years for your ancestors to develop and hone.
9. Don’t rely on your memory too much, because memories can change over time. Indeed accounts of eye-witnesses are only 50% accurate.
Common myths, Busted
1. You don’t have to be born as a genius. Due to Brain Plasticity, your brains can change throughout your life. So, even if you are not born as a genius, you can become one by training your brain.
2. Computer and video games are not always bad. They can actually improve your cognitive abilities (learning and problem-solving). However which type of games improve your cognitive abilities is not yet clear.
3. You don’t just use 10% of your brain. You use almost all of your brain all the time. But the intensity to which several areas of the brain are activated depends mostly on the activity you are doing at the current time. That’s why, sometimes, the solution to a problem materializes several days later, when you are not even thinking about it.
We hope that this blog post helped you understand about the different parts of the human brain and their functions. If you liked this blog post, you will like the following blog post too:
1. The human memory
October 27, 2019
The Best Painters Of All Time & Their Best Paintings

In this blog post, read about the best painters of all time. Look at some of their captivating paintings. Find out the motivation behind these paintings and the emotions they convey.

1. Leonardo Da Vinci (1452 AD – 1519 AD)

More commonly known as Leonardo Da Vinci, Leonardo di ser Piero da Vinci is a Renaissance painter. Many people around the world consider him as one of the best painters of all time.

Even though only 15 of his paintings survived, his paintings Mona Lisa and The Last Supper made him world famous. The former is the most popular portrait ever made while the latter is the most reproduced religious painting.

A self-portrait of Leonardo Da Vinci and Mona Lisa

He was born in Florence, Italy and worked in Rome, Bologna and Venice. When he was 14 years old, he joined the Studio of Andrea del Verrocchio, and trained there. Andrea del Verrocchio was the most famous painter and sculptor in Florence at that time.

2. Michelangelo (1475 AD – 1564 AD)

A self-portrait of Michelangelo

Michelangelo di Lodovico Buonarroti Simoni was a Renaissance painter. Revered as one of the best painters of all time, his most famous paintings are the scenes from Genesis (the first book of Hebrew scripture that describes the origin of the world and mankind) on the ceiling of the Sistine Chapel (where new popes are chosen) in Vaticanand the Last Judgement on its altar wall. These huge paintings were made by Michelangelo without the help of any assistants.

The Last Judgement (License terms)

Michelangelo was born in Caprese (known as Caprese Michelangelo today) in Italy and has worked in Bologna, Florence and Rome. When he was 13 years of age, he joined as an apprentice to Domenico Ghirlandaio where he planned to initially learn for 3 years. However, after one year, having learned everything there was to learn, he went on to study at the sculpture school in the Medici gardens.

Although Michelangelo`s paintings are very famous, he liked to call himself a sculptor, and engaged in painting only in his spare time. Some of his famous statues include David, Pieta, Moses and Madonna and the child, all of which are world famous.

He also contributed to the design and construction of St. Peter`s Basilica(Burial site of St. Peter, chief among Jesus`s Apostles and the first Bishop of Rome) in Vatican, which besides being the holiest catholic church, is also the largest church in the world.

3. Pablo Picasso (1881 AD –1973 AD)

Pablo Ruiz Picasso was a modern era painter who co-founded cubism (paintings made with 2D-planes rather than 1D-lines), co-invented collage and invented the concept of constructed sculpture (Statues with objects projecting out of them).

Born in Malaga in Spain, Pablo Ruiz Picasso got his surname from his father’s name (Ruiz) and mother’s name (Picasso) which is common in Spain. He has worked in Italy, France and Spain.

Pablo Picasso

In his lifetime, he produced 50,000 artworks including 1,885 paintings, 1,228 sculptures, 2,880 ceramics and 12,000 drawings. Most of his creations came from his imagination. “I paint objects as I think them, not as I see them.” – Picasso.

According to the art Market Trends report (as of 2015), based on the sales of his creations at auctions, Picasso remained the top-ranked artist.

Guernica

His famous paintings include Guernica, Les Demoiselles D`Avignon, The Weeping Woman, The Old Guitarist, Le Réve and The Three Musicians. While Guernica is renowned as one of the most powerful anti-war paintings in history, Le Réve was the fifth most expensive ($155 million) painting ever sold (as of March, 2013).

He used different styles including Cubism, Collage, symbolism, surrealism and neoclassicism.

The Weeping woman

Picasso is not only famous for creating so many works of art, but also falling in love with and living with a lot of women. He once fell in love with a woman 40 years younger than him and fathered 2 children with her.

4. Vincent Van Gogh (1853 AD – 1890 AD)

Vincent Willem van Gogh was a Dutch artist from the Post-impressionism era. Highly regarded as one of the best painters of all time in the history of western art, he is considered today to be the misunderstood genius since almost all his art gained traction after his suicide at 37.

He was well-known for his still-life, portrait and landscape paintings.

Self-portrait

Most of his adult-life was dominated by loneliness (he had no wife or children), ill-health and lack of a stable income. He changed jobs from being an art dealer to a school teacher to working at a bookstore to trying to be a pastor before finally becoming an artist. His younger brother Theo supported him financially and provided emotional support, who also encouraged him to become a professional artist.

Starry night

Sunflowers

Even though he started his professional art career pretty late and it lasted only a decade, he created about 2100 pieces of artwork during that time, some of which were used as the base for the creation of other art styles after his death.

He had a habit of regularly writing letters to his brother, sometimes to his sister and friends, which provide a pretty good biography of his life. Apart from Michelangelo who had his biography written, Vincent Van Gogh is another artist whose life has been documented so flawlessly.

Some of his famous paintings include The Starry night, Sunflowers and Irises. Till 1987, Sunflowers was the most expensive painting to be sold at an auction, which was broken by Irises two years later. As of today, Irises is the 15^thmost expensive paintingever sold.

5. Edvard Munch (1863 AD – 1944 AD)

Edvard Munch was a Norwegian painter. If Leonardo Da Vinci is known for The Mona Lisa, Edvard Munch is known for The Scream. He often used paintings as a means of showcasing his own emotions. Most of his works portray life and death scenes and convey the feelings of fear, loneliness, love, terror and jealousy. He used contrasting lines, darker colors, blocks of colors and exaggerated form to convey these emotions.

Most of his works focused on the style known as Symbolism.

Self-portrait with skeleton arm

Edvard Munch was brought up by his father who himself was suffering with mental illness. His mother died because of Tuberculosis when he was 5 years old and his favorite sister died because of the same disease when he was 14 years old.

Both these incidents as well as his father’s mental illness were a huge influence on him and his paintings later on. He also suffered from hallucinations.

Some of his paintings portray (and his style was inspired by) the tragic incidents that happened in his life. His most famous paintings are The Scream, The Sick Child (tribute to his deceased sister), Night in St. Cloud (darker memorial to his father), Madonna and Puberty.

The Scream

The Sick Child

6. Claude Monet (1840 AD – 1926 AD)

Born in 1840 in Paris and baptized as Oscar-Claude, Monet is the founder of the French Impressionist painting style. The word ‘Impressionism’ itself is named after his painting ‘Impression, sunset ‘. He painted several landscapes and portraits throughout his lifetime, that indicate his mastery at capturing the light and colors.

Claude Monet

Monet often painted a landscape and painted the same scene several times to capture the effect of change in light and seasons.

Some of the famous paintings of Claude Monet are Water Lilies, Rouen Cathedral, The Rue Montorgueil in Paris, Westminster bridge, Woman with a Parasol and of course, Impression Sunrise.

Impression sunrise

Water Lilies

Which of these best painters of all time do you like the most?

We hope that this blog post helped you learn about some of the best painters of all time. So, which of these artists do you like the most? Which of their paintings moved you? Tell us in the comments below.

October 27, 2019
Types of Satellite Orbits & The Differences Between Them
What is an artificial satellite? How does an artificial satellite stay in orbit? What are the different types of satellite orbits? These are the things that you will find out by reading this blog post.

Satellites are objects or heavenly bodies that orbit a planet, star or an asteroid.

Satellites can be classified into natural satellites and man-made satellites. For example, moon is the natural satellite of earth. On the other hand, the International Space Station is a man-made satellite. In this article, the term ‘satellite’ refers to man-made satellites only.

Artificial satellites

Sputnik 1 (Russian word for satellite), the first man-made satellite, was launched by the Soviet Union in 1957. It orbited the earth once every 96 minutes. Since then, almost 80 countries have launched more than 8,900 satellites.

As of 2018 only 1,900 of these are still operational. 3,100 satellites have become nonoperational, but still remain in earth’s orbit as space debris. The rest are somewhere in the outer space.

What keeps a satellite in orbit?

As you know already, every object exerts a gravitational force on another object. The higher the mass of the object, the greater is its gravitational force. The gravitational force of the Sun keeps the planets in orbit. Similarly, the gravitational force of the earth keeps the moon and artificial satellites in orbit around the earth.

However, the gravitational force alone is not enough for an object to stay in orbit. There has to be an equal and opposite force acting on these satellites. Otherwise, they will fall on earth. This opposite force is the satellite’s momentum. It is the product of the satellite’s mass and the velocity with which it moves.

On the other hand, without gravity, these satellites will leave their orbit and travel in a straight line away from earth. So, at every point in time, the gravitational force of the earth acting on the satellite and the momentum of the satellite have to be balanced. Only then can the satellite stay in orbit.

Velocity of the Satellite and its distance from Earth

The formula for the gravitational force acting on the satellite is :

The momentum of the satellite is :Now, for the satellite to stay in orbit, its momentum and the gravitational force acting on it should be balanced. But the gravitational force acts in the vertical direction towards the earth. So, the momentum of a satellite is perpendicular (90°) to the gravitational force.Therefore, we cannot say both these forces should be equal to each other. But they should be proportional to each other, i.e., if gravitational force increases, the momentum should increase for the satellite to stay in orbit, and vice versa. We can write that as follows :Since G and mass of the earth are constant, we can write this as :The velocity of the satellite should be inversely proportional to its distance from the earth. In simple words, the closer a satellite is to earth, the higher its velocity should be, in order to stay in orbit and vice versa.

Types of Satellite Orbits

Satellites are launched into different orbits around the earth. The type of orbit a satellite takes depends on its mission. Depending on their distance from earth, satellites can be classified into the following types.

High Earth orbit

Satellites orbiting the earth at a height of 35,786 km from the surface of the earth are said to be in High earth orbit.

Satellites at this altitude are said to be in a ‘Sweet spot’ because, they are orbiting the earth with the same speed as the rotation of the earth. This means that, a satellite at this altitude looks like it is staying still. Such orbits are called Geosynchronous orbits and are used for telecommunications as well as remote-sensing applications.

If they orbit earth at any other latitude other than the Equator, they will have the same longitude. But they can move north or south (fixed longitude but changing latitude).

If a geosynchronous satellite orbits the earth directly above the Equator, it is said to be in Geostationary orbit because it appears to stay at a fixed location above earth with no change in longitude and latitude over time. This gives a constant view of the location throughout the year that makes it extremely useful for weather monitoring. The weather reports and satellite views of locations come from geostationary satellites.

Medium Earth orbit

Medium earth orbits are closer to earth than High earth orbit. There are 2 important medium earth orbits.

Semi-synchronous orbit

It is a near-circular orbit around the earth at a height of 20,200 km. Satellites in this orbit complete one orbit in 12 hours. The satellite passes over the same 2 spots on Equator everyday and another 2 spots on the Equator every night. All the GPS satellites are in this orbit.

Molniya orbit

While the semi-synchronous orbit is near-circular, this orbit is elliptical, with the earth near one edge. This helps in providing communications to high latitudes (like Canada), because these latitudes cannot be covered using Geostationary and Geosynchronous orbits.

Low earth orbit

A low earth orbit is a near-circular orbit around the earth at a height of 160 km – 2000 km with an orbital period of 128 minutes or less. The mean orbital velocity needed for a satellite to stay in this orbit is around 7.8 km/s. Most of the scientific, spy and weather satellites are in this orbit. The international space station orbits around the earth in the low earth orbit at an altitude of 400 km.

International space station

The amount of energy required to place a satellite in low earth orbit is very less compared to the other orbital regions. Therefore, most of the satellites are launched to orbit the earth in the low earth orbit. However, in the low earth orbit, the drag caused by the atmosphere damages the satellites (due to the frequent collisions between the gas molecules and the satellite) traveling at such high velocities. This process is called orbital decay. Hence, the satellites need to be re-boosted (to maintain altitude) periodically or replaced completely.

Most of the satellites in this altitude that lose functionality are made to reenter earth, where they usually burn up. Therefore, this part of the orbit is congested with space debris – around 8,500 objects larger than 10cm and a million objects bigger than 2mm.

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Polar orbit

Satellites in the low earth orbit, which pass over the Earth from pole to pole are said to be in Polar orbit. Polar orbits are at an altitude of 200 km – 1000 km. Polar orbits are normally used for earth observation, weather and reconnaissance.

By the time a satellite in a polar orbit completes one orbit, the earth would have turned a little bit. So, the satellite will now be in an adjacent time zone when compared to its last orbit. A satellite in polar orbit completes one orbit in (mostly) 90 – 100 minutes. Hence, in one day, it will see most of the earth twice.

Sun synchronous orbit

Polar orbits that are synchronous to the Sun are called Sun synchronous orbits. These orbits are at an altitude of 200 km – 600km. In a Sun synchronous orbit, regardless of when and where the satellite crosses the Equator, the local solar time is always the same. That’s why it is called Sun synchronous.

For example, whenever and wherever the NASA’s Terra satellite crosses the Equator, the local time at that moment at that place is always 10:30 am. This is important for comparing images from different years to find changes in weather, etc.

Facts you probably didn’t know
1. You can see the International space station from the ground. It is the third brightest object in the night sky. In this website from NASA, you can find how and when to spot the International Space Station from your location.
2. The first living creature that was sent into orbit was a dog named Laika (Sputnik 2, 1957 by Soviet Union).
3. A satellite has 2 main components : An antenna for sending and receiving information from earth and a power source (mostly a solar panel).
4. In 2009 an American communication satellite and a Russian communication satellite collided in space.
5. There is a satellite that has been programmed to reenter earth after 8.4 million years. It will deliver a message from us to the future civilizations.
6. Satellites can be as big as a bus (6 tons) or can be as small as a 4-inch cube (1 kg).
7. Satellites are programmed to avoid asteroids so that they don’t collide with them.
We hope this blog post helped you understand what the different types of satellite orbits are. Find out what you learned in this blog post. Take the quiz on the types of satellite orbits now.

If you liked reading this blog post on the different types of satellite orbits, you may like our following articles too.
1. Planets of our solar system
2. How does the GPS in your cell phone work?
October 27, 2019
Different Types of Allergies – Causes, Symptoms, and Remedies
In this blog post, read about the different types of allergies, their causes, their symptoms and their remedies.

Even though allergies are not so common, they are increasing day by day. Learning about the different types of allergies and their symptoms can help you identify the allergy if you or your friend is suffering from it.

What causes an allergy?

An Allergy is caused when the immune system incorrectly identifies a harmless substance in the environment as a dangerous substance. This creates antigens. When your body comes in contact with these substances again, these antigens make the immune system release chemicals into your blood. The symptoms your body shows to these allergies are actually the reactions of your body to these chemicals. Depending on the chemical released, different symptoms can occur.

Some of the symptoms of an allergy include sneezing, runny nose, red eyes, swelling, shortness of breath, vomiting and diarrhea. About 20% of the people in developed countries have allergies. The following are some of the most common allergies that affect people.

Inflammation of the nose

Hay fever (Allergic rhinitis)

Among the different types of allergies, this is one of the most common allergies in the western world. Every year 10% to 30% of the people are affected. The most commonly affected age group is 20 to 40.

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Cause

The allergy was initially wrongly identified to be caused by hay. That’s how it got the name Hay fever. However, it is actually caused by the immune system overreacting to harmless substances in the air. These harmless substances may be pollen, pet hair, mold or dust.

Symptoms

Symptoms are similar to common cold (runny nose, watery eyes, sneezing and swelling around the eyes). But they can last for 2 weeks or more. Genetics and environmental factors are the reason behind hay fever.

Treatment

Antihistamines can be used to treat hay fever. However, it can have some side effects. Allergen immunotherapy over a period of 3 years or more has been found to be effective. Allergen immunotherapy exposes the patient to gradually increasing amounts of the allergens (material causing the allergy).

Inflammation of the skin

Atopic Dermatitis (Eczema)

A topic Dermatitis is another common allergy among the differnt types of allergies in the world. It affects almost 20% of the people in the world at some point in their lives. This is more common in children.

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Cause

Our skin, when healthy, protects us from irritants, allergens and bacteria. However, the skin becomes incapable of providing this protection. This may be due to genetic and environmental factors (sometimes due to food allergies). This is the cause for Eczema.

Symptoms

Dry and itchy (gets severe at night) skin with red or brownish gray patches often on the hands and legs. The skin can get thick and crack and sometimes be covered with bumps which leak fluid when crushed.

Related allergies

People who get Atopic Dermatitis are more prone to Asthma and Hay fever.

Treatment

There is no cure for Eczema. However, the following measures can help keep it under control.

Taking warm, short showers instead of long, hot showers; applying moisturizers twice a day; using gentle soaps and soft towels; and identifying the triggers (outside triggers – pollen, dust, etc; inside triggers – stress, obesity, etc; and food triggers – milk, eggs, etc) that worsen your condition and staying away from these triggers can help control Eczema. If you are interested, read about the different types of Eczema.

Inflammation of the airways of the lungs

Allergic Asthma

Allergic asthma is the most common type of a sthma. 60% of the people who already have asthma are prone to allergic asthma.

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Cause

The main cause of allergic asthma are allergens like pollen, pet dander, mold, cockroaches, and dust mites. Common triggers include tobacco, strong scent, pollution, cold air and fumes.

Symptoms

Symptoms of allergic asthma are wheezing, coughing, chest tightness leading to difficulty in breathing and shortness of breath.

Related allergies

Do you or someone else in your family have allergic asthma? Then you are more prone to hay fever and eczema as well.

Treatment

Allergic asthma cannot be cured.

However, home remedies like cleaning often using HEPA vacuum cleaners and using allergen proof bed-coverings can help reduce the contact with allergens. Using inhalers and taking certain steroids can help clear up the airways of the lungs.

Quick and Dangerous

Anaphylaxis

In some people, allergens can cause some of the above-mentioned reactions. However, for other people, the same allergens can cause life-threatening allergic reactions. The symptoms can occur rapidly and can cause death. Such a condition is called Anaphylaxis which often causes shock.

Have you or anyone in your family has already suffered from Anaphylaxis? Then you are more prone to this allergy.

Cause

Anaphylaxis can be caused by a variety of allergens. This includes food items, insect bites, other medications, latex and some exercises.

Symptoms

The early symptoms are also varied, including wheezing, chest pain, hoarse voice, nasal congestion, low pulse, swelling of skin, itching, rashes, vomiting, diarrhea, anxiety and head ache. However, when any of the symptoms including breathing difficulty, low blood pressure or lack of consciousness occur, it means this allergy has become life-threatening.

Treatment

Since Anaphylaxis is extremely dangerous, it is better to see a doctor immediately. Sometimes, the symptoms can disappear and return after a few hours. So, do not takeit lightly.

Immunotherapy (also used for treating cancer) is the process of artificially suppressing or activating the immune system. Immunotherapy is used to treat Anaphylaxis. Finding the allergen that caused the allergy and avoiding exposure to this allergen is another effective way to combat Anaphylaxis. Injecting Epinephrine (also used for treating cardiac arrests) is the most common emergency treatment for people suffering from Anaphylaxis. If there isn’t sufficient response, the injection is repeated after 5-15 minutes. People suffering from Anaphylaxis also wear jewelry indicating their condition and the allergen they are allergic to, so that people can help them if they become unconscious.

Food allergies

Food allergies are caused by various harmless food items. The various food items that cause allergies and their symptoms will be discussed in a later blog post.

Fun facts about the different types of allergies
1. Just like humans can be allergic to pet dander, pets (and other humans) can be allergic to human dander as well.
2. Our immune systems were designed to fight parasites. When we live in a clean environment breathing clean air, drinking clean water and eating clean food, our body starts identifying harmless food items as enemies. That’s why almost half of Americans are allergic to something.
3. Since food allergies are caused by proteins found in food, a team in Trinity college in Dublin tried to eliminate food allergies in mice by injecting them with parasites. Their experiment was successful; the immune system started ignoring the proteins and started fighting the parasites instead.
4. Inspired by the above experiment, Jasper Lawrence, who used to suffer from Asthma and other allergies, went to Africa and walked barefoot so as to infect himself with hookworms. As he had hoped, his asthma and other allergies weredefeated. He even started a business and was selling 35 hookworms for $3000.
5. There are women who are allergic to male ejaculate and therefore allergic to sex.
6. There are women who are allergic to their own sex hormones.
7. Some people are allergic to water. This could make people unable to take bath.
8. Organ donation also donates the allergies of the donor to the receiver.
We hope that this blog post helped you understand why some of the different types of allergies are caused, how to differentiate them, and how to treat them.

If this blog post helped you, kindly share it with your friends and family.

Helpful resource

This website helps you find and tackle your health problem based on the symptoms you have.

If you liked this blog post, you may also like the following blog posts:
1. Fat-soluble vitamins
2. Water-soluble vitamins
October 25, 2019