Tell about our Solar System ?

NASA has a fleet of spacecraft observing the sun to learn more about its composition, and to make better predictions about solar activity and its effect on Earth.

The four inner four planets — Mercury, Venus, Earth and Mars — are made up mostly of iron and rock.

Some planets like Earth are made of rock, and some like Jupiter are made of gas.

They are known as terrestrial or earthlike planets because of their similar size and composition. Earth has one natural satellite — the moon — and Mars has two moons — Deimos and Phobos.

Between Mars and Jupiter lies the Asteroid Belt. Asteroids are minor planets, and scientists estimate there are more than 750,000 of them with diameters larger than three-fifths of a mile (1 km) and millions of smaller asteroids

The hottest planet is Venus where the average temperature is 460°C, and the coldest is Uranus, which is -220°C.

The dwarf planet Ceres, about 590 miles (950 km) in diameter, resides here.

Mars is sometimes the called ‘the red planet’ because the rocks that it is made from are red.

A number of asteroids have orbits that take them closer into the solar system that sometimes lead them to collide with Earth or the other inner planets.

It is the closest planet to Earth, and is slightly smaller than Earth.

Earth is surrounded by a flotilla of spacecraft, and Mars has been visited by many spacecraft as well.

Some of the more prominent Martian missions include the Curiosity rover, the Opportunity and Spirit rovers

e Mars Reconnaissance Orbiter (which takes high-resolution pictures from orbit), and the Viking landers and rovers. Venus has been explored by American,

MESSENGER (now concluded) and BepiColombo (expected to launch in 2018).

The biggest planet is Jupiter.

The outer planets — Jupiter, Saturn, Uranus and Neptune — are giant worlds with thick outer layers of gas. Between these planets,

they have dozens of moons with a variety of compositions, ranging from rocky to icy to even volcanic (such as in the case of Jupiter's Io.)

Jupiter is made of gas and is so big that you could fit

all the planets' mass is made up of hydrogen and helium, giving them compositions like that of the sun. Beneath these outer layers, they have no solid surfaces

the pressure from their thick atmospheres liquefy their insides, although they might have rocky cores. Rings of dust, rock, and ice encircle all these giants, with Saturn's being the most famous.

planets the size of Earth inside it.

Comets are often known as dirty snowballs, and consist mainly of ice and rock.

There is even a storm on Jupiter that is bigger than Earth – this storm has been blowing for hundreds of years and is called the ‘Great Red Spot

When a comet's orbit takes it close to the sun, some of the ice in its central nucleus turns into gas that shoots out of the comet's sunlit side

Saturn is famous for having rings of small pieces of ice and dust around it. Like Jupiter, it is made of gas and is much bigger than Earth.