ASTEROIDS
Asteroids are also known as minor planets. These are mostly composed of rocks and airless remnants from 4.6 billion years ago, the early formation of the solar system. Most of the asteroids are found to be orbiting within the well-known Asteroid Belt, between Mars and Jupiter. The total mass of all asteroids when put together is less than the total mass of the Moon.
Asteroids can reach as large as Ceres, which is 940 kilometers (about 583 miles) across. On the other end of the scale, the smallest asteroid ever studied is the 6-foot-wide (2 meters) space rock 2015 TC25, which was observed when it made a close flyby of Earth in October 2015.
Composition of Asteroids
These rocky objects are mostly made of rocks, some also have clay and silicate in them, as well as various metals like nickel and iron. But the composition of these is mainly based by how close it is to the sun. It is believed that when asteroids are nearest to the Sun, they are mostly made of carbon, with smaller amounts of nitrogen, hydrogen and oxygen. Those asteroids that are further are made up of oxygen and silicon, the number one and number two most abundant elements in the Earth’s crust. The metallic asteroids are composed of up to 80% iron and 20% a mixture of nickel, iridium, palladium, platinum, gold, magnesium and other precious metals such as osmium, ruthenium and rhodium. There are a few that are made up of half silicate and half metallic.
