What are Asteroids and how are they formed?

Most of the time while reading our daily newspaper or seeing news we came across the news related to asteroids, meteors, comets etc. Do you know what are asteroids, how they are formed? Where they are present in space? What is the difference between an asteroid and a comet? Let us find out!  
Aug 27, 2019 12:59 IST
facebook Iconfacebook Iconfacebook Icon
What are Asteroids?
What are Asteroids?

Asteroids are also known as space rocks. These are also rocky remnants that travel in the solar system. Scientists are always eager to know about the early days of solar system so they study asteroids because they contain clues about the early days of solar system.

Our Solar system formed around 4.6 billion years ago from a collection of gas and dust that surrounds Sun. Much of the gas and dust formed planets and some of the debris left over. Let us tell you that some debris shattered as remnants of planetesimals within the young sun's solar nebula that never grew large enough to become planets. Due to massive gravitational pull from Jupiter other debris never came together.

What are Asteroids?

Asteroids orbit the sun and are rocky, metallic bodies. From various rocks and metals asteroids are made up of. Mainly from nickel and iron metals, asteroids are made. Asteroids are also known as minor planets because they are very small than planets or moon. Asteroids does not have atmosphere but it is said that around 150 asteroids are known which have small moons that orbit them and even some have two moons. In facts some asteroids are also binary that is double where two rocky bodies of roughly equal size orbit each other and some are triple also. In 2013 scientists were surprised and discovered that atleast one asteroid have rings.

What if an asteroid was about to hit Earth?

Where in Space Asteroids are located?

Most of the asteroids are located in the asteroid belt in a large donut-shaped ring between the orbits of Mars and Jupiter. Asteroids orbit approximately 2 to 4 AU (186 million to 370 million miles/300 million to 600 million kilometers) from the sun.

Sometimes due to gravitational interactions with planets some asteroids get altered and as a result they end up coming closer to the Sun and to the Earth. These Asteroids are called Near Earth Asteroids.

When Asteroids actually cross Earth's orbital path are called Earth-Crossers and an asteroid is called a Potentially Hazardous Asteroid (PHA) if it will come less than .05 AU from Earth.

Also according to some astronomers Asteroids also reaches solar system in the Kupier Belt and Oort Cloud. It is said that there are millions of asteroids in the solar system. It is estimated by some scientists that the belt of asteroid gas 1.1 and 1.9 million asteroids which are larger than 1 kilometer or 0.6 mile in diameter and there are millions of smaller ones.

How Asteroids are formed?

Do you know that most of the asteroids are irregular in shape and it is difficult to spot them in the space because they are made up of dark material and are difficult to find against the darkness of outer space.  Asteroids revolve around the sun in elliptical orbit and have some quite erratic movements. 

As we have read above that asteroids are made up of rocks with some clay, silicate and with different types of metals mostly nickel and iron. In some asteroids according to the astronomers some kind of precious metals are found like gold and platinum. In some asteroids wide varieties of minerals have also been found like olivine and pyroxene and these minerals are also found on meteorites that have landed on Earth.

Most of the asteroids also contain vast amounts of carbon which shows that they closely follow the elemental composition of the Sun. Dawn mission observation indicates that water may have flowed across the surface of Vesta and may be asteroids also contain water or ice in their interiors.

No doubt asteroids are different from comets.

Comets usually have tails and are made up of ice and debris sublimating when comet gets close to the sun. And we have study above that asteroids does not have tails even they come closer to the sun. Let us tell you here that astronomers have spotted tails in some asteroids like asteroid P/2010 A2. This happen when asteroid hit with other asteroids and dust or gas is ejected from their surfaces which create an effect of tail. Therefore, such types of asteroids are known as "active asteroids" and they are rarely found.

So, now you may have understood about asteroids and their formations.

World Asteroid Day 2019: Current Events and History

ISRO’s Space Programme: Timeline from 1960s to 2019