The galaxies in the universe are about two thousand billion years old. Our galaxy is called the Milky Way and it is composed of about 400 billion stars; its shape is a spiral. The arms of the Milky Way are: Perseo, Swan, Sagittarius, Orion, Centaur. Another curiosity is that scientists recently discovered a black hole in the centre of the Milky way. Our solar System is in Orion’s arm. The solar system is composed by 8 planets.
Mercury: the first planet of the Solar System beginning from the Sun. During the day on Mercury there are 430°, whereas at night there are -185°.
Venus: this is the second planet of the Solar System. Venus’ atmosphere is made of acidic and toxic gases and it’s inhospitable for a terrestrial being. Venus looks like a star because the clouds that surround it reflect the rays of the Sun. It looks very bright.
Earth: planet Earth is the only planet on which life is possible because it has liquid water. It has an atmosphere that is divided in layers. It has only one natural satellite which is the moon.
Mars: scientists think that a long time ago on Mars there was life. However, if there was, they think that it would have been underground. No one has proven that in the past or in the present there has been life. Now there is a robot-scientist laboratory on Mars.
Jupiter: could have been a star but it was too small; if Jupiter had become a star, there would have been life on Neptune. It is the biggest planet in the Solar System and it has a very thick atmosphere.
Saturn: Saturn is the sixth planet from the sun. It isn’t the only with rings but it has definitely the most beautiful ones; there are six of them and they are separated from space. They are made of pieces of ice and rock. It has 53 moons and 9 moons of which we are not certain if they exist. One year on Saturn are 29.5 Earth years. It also has a thick atmosphere and it is almost entirely made out of hydrogen and helium. It is a gas ball like Jupiter.
Uranus: It’s made of water, methane, and ammonia fluids with a small rocky center. Its atmosphere is made of hydrogen, helium and methane. The methane makes Uranus blue. It has 13 rings. One year on Uranus is 84 Earth years and one day is equal 17 Earth hours. It isn’t a ball of gas like Jupiter and Saturn but it is a ball of ice. It also has 27 moons.
Neptune: Neptune like Uranus is a giant ball of ice surrounded by 6 rings. Neptune has a thick, windy atmosphere. One day on Neptune is 16 hours; and one year are 164 Earth’s years. There are 13 moons plus one which is unconfirmed.
Francesca and Francesca (Class 5)