Planets


PLANETS


What is a Panet?

•         The celestial object that revolves around the sun is called a planet.

•         The planets were formed during the process of solar system formation, when clumps began to form in the disk of gas and dust.

 

Mercury:

•         Mercury is the planet closest to the Sun.

•         Less than half of the size of Earth, it is the second smallest planet in the solar system.

•         Mercury has a very little atmosphere, and similar to the Moon, has a dusty surface covered with craters.

Figure 8: Mercury

•         It takes only 88 days to orbit once around the sun, but then, each day on Mercury is as long as almost two months on the Earth.

•         This is because it rotates very slowly on its own axis.                                                             

•         This tiny planet does not have any rings or moons.

•         NASA’s latest mission to Mercury is called Messenger. 

•         The Messenger spacecraft entered Mercury’s orbit in March 2011 and is sending back new pictures of the planet. 

•         Messenger is now moving with Mercury around the Sun.

 

Venus:

•         Venus is the brightest planet and is sometimes visible with the naked eye.

•         The size of the planet is similar to Earth’s, so Venus is sometimes called “Earth’s twin”.

•         Venus is made up of almost the same type of materials as the Earth.

•         Venus has volcanoes, mountains and sand, just like Earth.

Figure 9: Venus

•         A thick layer of clouds around Venus causes it to appear bright white from the Earth.

•         It reflects a lot of sunlight and that is why we see it as a bright dot in the sky.

•         Like Mercury, it does not have any satellite.

•         It takes about 224 days to travel once round the sun.

 

Earth:

•         Earth is the third planet from the sun, present in between Venus and Mars.

•         It is a mid-sized planet, larger than Pluto, Mercury, Venus and Mars, and smaller than Jupiter, Saturn, Uranus, and Neptune.

•         The Earth has one moon, which is approximately one-fourth the size of the planet itself.

Figure 10: Earth

•         The orbit of the Earth is elliptical.

•         It is a unique planet as it is the only known planet where life exists.

•         About 70% of the Earth's surface is covered by water and the temperature is moderate enough to support life.

•         Moon is the Earth's only natural satellite.

 

Mars:

•         Mars is the fourth planet in the solar system, present in between Earth and Jupiter.

•         It is known as the “Red Planet” due to its red colour.

•         This colour is due to the layer of rusted iron dust.

•         Mars is about half the size of Earth.

Figure 11: Mars

•         A very thin layer of air covers the planet.

•         Its atmosphere is thinner than the Earth’s atmosphere, but it causes Mars to have weather, including clouds and dust storms.

•         Its atmosphere has a lot of carbon dioxide and a small amount of oxygen and water vapour.

•         Evidence suggests that on Mars’ surface, there were rivers, streams, lakes, and even an ocean.

•         As Mars’ atmosphere slowly depleted into the outer space, the surface water evaporated permanently.

•         Today the only water on Mars is either frozen in the polar caps or is present underground.

 

Jupiter:

•         Jupiter is the largest planet in the solar system.

•         It is so huge that, about 1,300 Earths could fit inside the planet.

•         Jupiter is a gas planet, which means that it is a giant cloud mainly composed of hydrogen and helium, held together by gravity.

Figure 12: Jupiter

•         Because Jupiter is a gas planet, it has no real surface.

•         The swirling gas clouds create a sort of weather that includes storms.

•         The most well known of these storms is the Great Red Spot, which is visible in photographs of Jupiter.

•         It has the largest number of satellites (more than 60) and takes about 12 years to orbit the sun.

 

Saturn:

•         Saturn is the sixth planet in the solar system, present in between Jupiter and Uranus.

•         Saturn is the second largest planet in the solar system.

•         Similar to Jupiter, it is also made up of gas, which makes it the lightest planet.

•         Saturn is so light that it could float in water.

Figure 13: Saturn

•         It takes about 29 1/2 years to finish one revolution around the sun.

•         Saturn is well-known for its rings.

•         These rings are formed by water, ice, and rocky particles with icy coatings.

•         The rings are held in place around Saturn by the moons that also orbit this large planet.

•         The gravity of these moons cause the gaps that are seen in between the rings.

 

Uranus:

•         Uranus is the seventh planet in the solar system, present in between Saturn and Neptune.

•         It is about four times the size of the Earth, but compared to its large neighbour- Saturn, Uranus appears very small.

•         Like Saturn, Uranus is a gas planet and has rings, but it is different from the other gas planets.

Figure 13: Uranus

•         It revolves around the sun once every 84 years.

•         Uranus contains methane gas in addition to hydrogen and helium.

•         This methane gas causes the planet to appear blue-green in colour.

•         Uranus has 27 moons.

 

Neptune:

•         Neptune is the eighth planet from the Sun, present in between Uranus and Pluto.

•         The distance between Neptune and the Sun averages almost 2.8 billion miles.

•         Neptune completes an orbit around the Sun just once every 165 years, but it rotates approximately every 16 hours.

Figure 14: Neptune

•         It is a stormy blue planet with a molten rock core.

•         Around the core is a layer of very cold water, which moves gradually into a top layer which is made up of hydrogen, helium, and a small amount of methane.

•         This methane gives the planet its blue colour.

•         Like the other gas planets, Neptune has rings.

•         Neptune’s rings are made of small, dark clumps of rock.

•         Neptune has 8 moons.