solar system (inner planets)

     The Solar System consists of the sun and every thing that orbits it. 8 planets orbits the sun and more than 160 moons orbit the planets. There also more than millions other objects orbiting the sun, including asteroids and comets. the sun's gravity holds the solar system together.

     The solar system began from a swirling cloud of gas and dust called Nebula. Around 4.6 billion years ago, the solar system began to form. It may have been started by a supernova ( A huge explosion of a star). As the nebula collapsed it started spinning . Clumps of gas and dust formed in the collapsing cloud grew bigger and bigger as the gravity pulled more and more gas and dust towards them. A dense of mass formed at the centre of the nebula, which increased in temperature and eventually became our sun. The remaining gas and dust flattened into a spinning disc, later forming the planets.

     The sun is the closest star to earth although its 169,600,000 KM away. The sun is made of super hot gases, mostly hydrogen and helium. It's core (centre) is 15 million degree C hot. About 4 million tons of the sun's mass vanishes every second! This is because nuclear fusion changes some of the sun's mass into energy. Energy produced by nuclear fusion travels from the sun's core to the surface takes 200,000 years and when it leaves the sun it will take 8 min to reach earth.

      Mercury is the suns closest planet to the sun and also the smallest planet in the solar system. It's made of rock with a big iron core, and very dense for its size. Mercury has 1 of the biggest impact craters in the solar system. It's called Caloris Basin it measures1550 KM across. Planets closer to the sun have to be faster than those farther away, or i will be pulled into the sun. Mercury takes 88 earth days to orbit once. However, it spins very slow that a day on Mercury lasts 176 earth days. The side of Mercury that faces the sun reaches up to 430 degree C hot, but at the opposite side it's -180 degree C.

       Venus is the 2nd planet from the sun and almost the same size as earth but the 2 planets very different. It's rocky surface is hidden under carbon dioxide atmosphere that traps the sun's heat making it the hottest planet in the solar system. Venus spins the opposite direction to the other planets and also takes 243 earth days to spin once.1 way to see venus's surface is using radar. Radar can send radio waves from a spacecraft, through a planet's atmosphere to bounce off the surface below.

       The 3rd planet from the sun is Earth. Its is a mixture of gases, mainly nitrogen and oxygen. It also contains water vapor, carbon dioxide and other gases. This mixture is called air. without there will be no life at Earth. Earth tilts as it travels around the sun, this tilt produces the seasons. Earth also behaves as a giant magnet. Liquid iron swirling around Earth's core create electrical currents that produces magnetic field. particles flying out of the sun cause a glow in the sky called an aurora, Earth's magnet field steers the particles into upper atmosphere near the north and south poles. Here they collide with particles of gas, making them glow.

     The 4th planet from he sun is Mars also known as the red planet because its color is red. Mars has the biggest volcano in the solar system, Olympus Mons. It's almost 3 times bigger than mount everest, Mars also has the biggest canyons, Valles Marineris. It's 9 times longer, 20 times wider and more than 4 times deeper than grand canyon. The north and south poles of mars are covered with ice and stay frozen all year round. There are plans to send astronauts to mars this century. A spaceflight would take 9 months. Astronauts would then have to stay 18 month before the planets are close enough again for return journey to Earth.

   Between mars and jupiter is the asteroid belt, if you want more information cheek this.
                                           https://en.wikipedia.org/wiki/Asteroid_belt