The solar system and Earth 🌎

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There are alot of planets in our solar system (including Earth) some are dwarf planets too! Let's start with Mercury.

Mercury is the smallest rocky planet, is not much bigger than the Moon and the surface is covered in craters. It takes Mercury 88 days to orbit the Sun, and 59 days to rotate once. Because Mercury rotates so slowly on its axis, but orbits so quickly, by the time it has done a complete rotation, the Sun is in a different place.This means that a day, from sunrise to sunset, lasts about two Mercury years, or 176 days!

Venus. Venus is the second planet from the Sun. It takes 225 days to to around the Sun, but it takes 243 days to rotate on its axis. So a day on Venus lasts longer than a year! Venus is the nearest planet to Earth. Like Earth, it has an atmosphere, but the atmosphere of Venus is very different to ours. The most common gas in Earth' atmosphere nitrogen, but about 98% of Venus' atmosphere is carbon dioxide. The clouds on Venus are made of sulphuric acid, not water. It would be no fun to get caught out in the rain on Venus!

Mars. Mars is the fourth planet from the Sun, and is about half the diameter of Earth. A day on Mars is a similar length to a day on Earth, but it's year is much longer. Mars takes about twice as long as Earth to orbit the Sun. Also, it's orbit is more elliptical (oval) than that of the other planets. This means that the temperature changes between summer and winter are much greater than on Earth.

Uranus. Uranus was discovered in 1781 by William Herschel. It was the first planet to be discovered using a telescope. Unlike other planets , it cannot be seen with the naked eye. Like Jupiter and Saturn, Uranus rotates quite fast , despite being 51,118km (31,763miles) across. A day on Uranus is just 17 hours long. This means it looks like a squashed circle, or an ellipse.

Neptune. After the discovery of Uranus, scientists spent a long time observing the planet and working out its orbit. From Newton's laws of gravity, they knew how Uranus should orbit. But Uranus' orbit did not fit with the predictions. Scientists guessed that there must be another planet out there, pulling at Uranus and changing the shape of its orbit. The mystery planet was discovered on 23 September 1846 by Johann Halle and Heinrich d'Arrest. It became known as Neptune is so far away that it takes 164 years to orbit the Sun, but again it has very short day - just over 16 hours.

Finally, of course, EARTH! We live on Earth. It is a very special planet - it is the only place n the Solar System where we know life exists. No one has found any evidence of life gems elsewhere in the Solar System, it probably won't be a little green men. It is much more likely that there will be microbes. These could be still alive, or they may be extinct. The life forms that have evolved on Earth need corbon, organic chemicals, and water, as well as a source of energy. Life elsewhere in the Universe might need all these things, or it might need very different conditions.

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