Guide to our Solar System
Our Solar System consists of one sun and eight planets that are gravitationally bound in orbit around it. Our solar system is Sol and is located in the Milky Way galaxy. The Milky Way galaxy is a spiral bulge galaxy. This means that there are arms that spiral around the centre point of the galaxy. Sol is located on the outer of the arm called 'Orion'. The Milky Way is one of the millions of galaxies in the universe.
Planets
Mercury
Mercury is the closest planet to the sun, with an average distance of about 58 million kilometres away. Its diameter is 4,878 km at its equator which is about two-fifths of the Earth's diameter. It takes roughly 58.6 days for mercury to rotate, and it orbits the sun once every 88 days. The maximum surface temperature is 465°C and the minimum is -184°C. The mass of mercury is 3.3 x 1023 tons. Mercury's atmosphere is made up of hydrogen and helium. Mercury has no moons.
Venus
Venus is the next closest planet to the sun. It is 41,840,000 km away. It appears as a yellow white colour and has a diameter of 12,100 km, which is about 1040 km smaller than the diameter of Earth. The length of a day on Venus is the equivalent of 243 Earth days. Venus' mass is 4.87 x 1024 kilograms. The atmosphere on Venus is mad up of carbon dioxide. nitrogen and sulfuric acid. The temperature on Venus varies from 500 degrees Celsius to -32 degrees Celsius. Venus has no moons.
Earth in detail
The Earth is the third planet from the sun. It is estimated to be 4.54 billion years old. The average temperature on Earth varies from -90°C to 60°C. The Earth is 71% water. Only 3% of the Earth’s water is fresh water. This is extremely important as all like on Earth requires water. The average depth of the ocean is 3800 metres and the average height of the land, above sea level, is 840 metres. The Earth’s atmosphere is made up of various gases, 78% nitrogen, 21% oxygen, 0.9% argon gas and 0.1% other gases. Most creatures, such as mammals and most reptiles, require oxygen to live. It takes the Earth 365.25 days to orbit the sun. The length of a day on Earth (the time it takes the Earth to make one full rotation on its own axis) is 24 hours. The Earth has only one moon, called The Moon. The surface area of the Earth is 510 million kilometres. The mass of Earth is 5.98 x 1024 kilograms. The Earth is blue, green, brown and white due to the water, plant life, soil and clouds.
Mars
Mars is the planet that is found just after Earth, 227.9 km away. Mars has a diameter of 6796 km and appears red in colour. A day on Mars is 24.6 Earth hours. The mass of Mars is 6.42 x 1023 kilograms and has two moons. Mars's temperature varies from -140 to 20 degrees Celsius. The atmosphere on Mars is made up of mainly carbon dioxide, but also includes nitrogen and argon.
Jupiter
Jupiter is 778.3 km away from the sun making it the fifth closest. Jupiter's diameter is 143,000 km , which means that more than 12 Earth's can line up across its diameter. There are 18 known moons orbiting Jupiter. A day on Jupiter is 9.84 Earth hours. Jupiter appears as brown, red, blue and white. The mass of Jupiter is 1.90 x 1027 kilograms, and its average temperature -153 degrees Celsius. Hydrogen, Helium and Methane make up Jupiter's atmosphere.
Saturn
Saturn is the next closest planet to the sun, and at its closest Saturn is 1190.4 million km away from the Earth. Saturn has a diameter of 120,660 km which is about ten times larger that Earth. A day on Saturn is roughly 11 hours in Earth days. Saturn has at least 62 moons which includes: Titan, Hyperion, Mimas and many more. The average temperature on Saturn is -178 degrees Celsius. Saturn's atmosphere is made up of Hydrogen and Helium.
Uranus
Uranus is 2,871 million kilometres away from the sun. It appears light blue in colour and has a diameter of 51,000 kilometres. The length of a day on Uranus is 17.9 Earth hours. There are 15 moons orbiting around Uranus. The maximum temperature on Uranus is -184°C. The atmosphere on Uranus is made up of hydrogen, helium and methane. Uranus’s mass is 8.68 x 1025 kilograms.
Neptune
Approximately 4406.1 million kilometres away from the sun is Neptune. Neptune is the eighth and last planet in our solar system. It appears blue in colour and its diameter is 50,000 kilometres. Neptune has two moons and a mass of 1.02 x 1026 kilograms. The length of a day on Neptune is 19.1 Earth hours. The average surface temperature on Neptune is -223°C. Hydrogen, helium and methane make up Neptune’s atmosphere.
How our Solar System and Earth's Moon was formed
Scientists believe that our Solar System formed 4600 million years ago. They have theorised that our solar system was originally a cloud of gas and dust. This cloud was disturbed, possibly by a nearby star exploding in a supernova. This explosion made waves which squeezed the cloud. This squeezing caused the cloud to collapse. As the cloud collapsed gravity began to pull the gas and dust together. As the cloud was being pulled together it began to spin. Eventually the cloud got hotter and denser in the centre with a ‘disk’ of gas and dust surrounding. At this stage our universe was hot in the centre and cooler at the edges. As the disk got thinner particles began to stick together and form clumps. Some clumps got bigger and eventually forming planets or moons. Near the centre of the disk, where the Earth was formed, only rocky matter could stand the heat. Icy matter and rocky material settled in the outer regions of the disk, this was where planets like Jupiter formed. This accounts for the differences in the composition of the inner and outer planets in our Solar System. The cloud continued to fall in which resulted in a centre so hot that a star, our Sun, could form. The sun blew off most of the gas and dust from our newborn universe with a strong stellar wind.
There are four main theories for the formation of the moon. The first theory states that the moon formed in exactly the same way as planets. That is, through the coalescing of gas and dust during the solar systems formation. The second theory states that the moon is just a captured asteroid. The third theory states that when the earth originally formed it was spinning so rapidly that it split in two. This theory is often referred to as the “Fission Theory”. The fourth theory is the one most scientists tend to follow. This theory states that when the earth was quite young a planet, approximately the size of Mars crashed into it. This planet was moving so fast and crashed into the Earth with such force that it was completely destroyed and nearly destroyed the Earth. The molten iron in this planets core continued to travel through the earth and was included in the Earth’s core. This explained why there is very little iron in the moons core. The crash has been dubbed the “Big Splash”. It sent tons of rock and debris into orbit around the Earth. Over many years these fragments coalesced to form the moon.
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