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 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 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 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 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 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 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 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 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.