protoplaneettisissa

Protoplanetary disks are vast, rotating structures of gas and dust that surround young stars. These disks are considered the birthplace of planets. The material within a protoplanetary disk is drawn from the same cloud of gas and dust that formed the star itself. As the star contracts, its angular momentum causes the remaining material to flatten into a disk shape.

Within this disk, the dust grains gradually collide and stick together through a process called accretion. These small clumps grow larger, eventually forming planetesimals, which are kilometer-sized bodies. Planetesimals continue to collide and merge, leading to the formation of protoplanets, which are larger than planetesimals and can be hundreds or even thousands of kilometers in diameter.

The composition and temperature of the protoplanetary disk play a crucial role in determining the types of planets that form. Closer to the star, where temperatures are higher, rocky planets tend to form because only rocky materials can withstand the heat. Further out, in cooler regions, volatile compounds like water ice can condense, allowing for the formation of gas giants and ice giants. The gas in the disk also contributes to the growth of these larger planets, as they can accrete significant amounts of gas. Over millions of years, the gas and dust are either incorporated into planets, ejected from the system, or form smaller bodies like asteroids and comets.