- What is an Asteroid ?
Asteroids are small, rocky objects that orbit the Sun. Although asteroids orbit the Sun like planets, they are much more smaller than the planets. The term "asteroid" refers to the minor planets of the inner Solar System, including those co-orbital with Jupiter. Larger asteroids are often called planetoids. Asteroids are seen in individual and groups. They are usually seen as asteroid belt between the planets Mars and Jupiter.
- How did the asteroids originate ?
Asteroids are left over from the formation of our solar system. Our solar system began about 4.6 billion years ago when a big cloud of gas and dust collapsed. When this happened, most of the material fell to the center of the cloud and formed the sun.
Some of the condensing dust in the cloud became planets. The objects in the asteroid belt never had the chance to be incorporated into planets. They are leftovers from that time long ago when planets formed. Most of them got into the asteroid belts due to gravitational pull and hence are in group, whereas the individual ones wander here and there in the Solar system
- Facts about Asteroids
Because the asteroids formed in different locations are at different distances from the sun, no two asteroids are alike. Here are a few ways that they differ:
Asteroids aren’t all round like planets. They have jagged and irregular shapes.
Some asteroids are hundreds of miles in diameter, but many more are as small as pebbles.
Most asteroids are made of different kinds of rocks, but some have clays or metals, such as nickel and iron.
The largest asteroid is called Ceres. It is about one-quarter the size of the moon and orbits the sun between Mars and Jupiter in a region called the asteroid belt.
- What to learn from Asteroids
Since asteroids formed at the same time as other objects in our solar system, these space rocks can give scientists lots of information about the history of planets and the sun. Scientists can learn about asteroids by studying meteorites: tiny bits of asteroids that have flown through our atmosphere and landed on Earth’s surface. Using the samples of these objects scientist can detect the traces of water outside the Earth which suggests the possibility to find life outside the Earth premises.
- Previous studies on Asteroids
Several NASA space missions have also flown by and observed asteroids. The NEAR Shoemaker spacecraft landed on Eros, an asteroid near Earth, in 2001. Then, the Dawn spacecraft traveled to the asteroid belt in 2011 to orbit and study the second largest object there, Vesta. Vesta is so large it's like a small planet. In 2012 Dawn left Vesta and went into orbit around the largest object in the asteroid belt, dwarf planet Ceres.
In 2016, NASA launched the OSIRIS-REx spacecraft to study an asteroid near Earth named Bennu and bring a sample of the asteroid back to Earth! In 2018, OSIRIS-REx went into orbit around Bennu. Bennu is the smallest world ever to be orbited by spacecraft. OSIRIS-REx will spend two years studying Bennu’s surface, looking for the best place to take a sample.