The solar system is made up of a star surrounded by planets and other objects. Many people had thought that planet earth is the only place in the universe where life exists. But this view changed in 1995 when astronomers found a solar system that is similar to ours, though it is not known for sure whether humans can survive in it like the planet earth.
In 1995, astronomers found a planet going around (orbiting) a distant star like our sun. Since then they have found other solar systems. Astronomers now think that there are many solar systems in the universe. They do not know whether there is life in any of these other solar systems.
Despite all the advancement in science and technology, astronomers have not been able to understand other planets as they do our own planet. Thus, it is only our solar system that we know most about; the sun is at its centre. Our solar system includes everything that orbits around the sun. Planets, moon, asteroids, comets, gas and dust are all part of the solar system
Our solar system lies near the edge of the Milky Way Galaxy. A galaxy is a huge collection of stars. The Milky Way is shaped like a whirlpool. All the stars in the galaxy, including our sun, orbit around the centre of the Milky Way.
We are told the sun like other stars, is a hot ball of gas. Hydrogen and Helium are the main gases in the sun. Almost all the energy in our solar system comes from the sun. The sun changes hydrogen into helium to create light and heat, these changes take place deep inside the sun.
The Nine planets
There are nine planets in the solar system. Eight of these nine planets belong to two groups known as the inner planets and the outer planets. There are four planets closets to the sun; they are called the inner planets.
They are Mercury, Venus, Earth and Mars. The inner planets are also called the rocky planets, because they are made mainly of rock and iron. There are also four outer planets: namely Jupiter, Saturn, Uranus and Neptune. They are called the gas giants because they are very huge and made mainly of gas. The farthest planet from the sun is a small ball of ice called Pluto. Some astronomers think that Pluto should not be called a planet.
Mercury is the closest planet to the sun. It has a large core, or center, that is made of iron. Venus, the next planet from the sun is the hottest of the planets. The temperature on Venus is said to be about 890 Fahrenheit (about 477 Celsius).
Earth is the only planet known to have life. It also has plenty of liquid water. There are signs that liquid water may once have flowed on Mars but now Mars is cold and dry. What happened to the water on Mars is a great mystery that scientists are trying to solve.
Of all the planets, Jupiter is the largest of them all. It is surrounded by a thick atmosphere made of hydrogen and helium. Jupiter cloud look like white, brown and orange stripes going around the planet. There is an oval shaped red spot in the clouds.
Astronomers think this spot is a big storm that has been raging for hundreds of years. Saturn is the second largest planet and the sixth planet from the Sun. it has bright rings around it. Uranus and Neptune look like smooth blue balls. Methane gas gives these planets their blue color. Pluto is the smallest planet in our solar system, it is far from the sun and very cold. Temperature on Pluto can drop to -387 Fahrenheit (-223 Celsius).
Formation of the Solar System
We are informed by astronomers that the solar system may have come from a swirling cloud of gas and dust. First a star, our sun, formed from a clump in the cloud. Then the planets, their moons and the other objects in the solar system formed from the leftover gas and dust.
Other stars and system in the universe may have formed the same way. In fact, new solar systems are still forming from giant clouds of gas and dust.