Planetesimals are the precursors and the building blocks of the current day planets in the solar system. They are akin to the asteroids in the sense that all the cosmic bodies currently in the solar system were formed simultaneously 4.6 billion years ago from a huge cloud of dust and gas known as solar nebula.
Gravitational forces pulled them together ever closer and closer which resulted in the formation of sun at the centre and the planets surrounding the sun. But not all planetesimals eventually wound up as a planet. Jupiter as the largest planet exerted a gravitational pull on many of these celestial bodies once it was formed and these planetesimals were pulled into a stable orbit around Jupiter forming what is now called as the asteroid belt. The asteroids are either the original planetesimals or their fragments.
These asteroids are of three main types:
(1) Chondritic which is made up of clay or rocky material and probably the original planetesimals. Dan Brown’s Deception Point explores this type of asteroid in a nail biting science thriller.
(2) Stony asteroids made of silicate materials and nickel iron. (fragments of other asteroids)
(3) Metallic asteroids from nickle iron usually formed from core of shattered planetesimals.
See what Nina & Nana have to say about planetesimals today.
This post is a part of the #NinaAndNana series I co-host with Kanika G.