Micro Life Zone
Asked by cocacolarulez to Arti, Chris, Dustin, James, Steven on 19 May 2012.
Keywords: earth, form, planet
This is a great question.
The best model that explains planetary formation is the one that describes how a solar system comes about, called the Nebula hypothesis, or the solar nebular disk model.
Stars form from the clumping together of matter and in doing so form a disk of material around itself. This disk rotates as the little sun rotates. If there is enough material in the disk, planets will also begin to form from this extra material. As more stuff clumps together, gravity of the body increases which continues to attract more stuff.
Eventually when the object is massive enough where its shape is determined by its gravity, and therefore roughly round, we call it a planet.
Water appears to have come to the earth during the late heavy bombardment. This was the period where the earth was being slammed with lots of the left over material, asteroids etc as the early solar system formed.
So in short, due to gravity, the dust and material attracts together, which increases the gravity and attracts more stuff.
But there is still a lot we don’t understand. The formation of planetesimals is one thing. A planetesimal is a piece of material about 1 km in size. Once they reach this size, they can attract one another quite easy. But getting to this size is not well understood at all.
Also the formation of gas giants is not well understand.
So the model of planetary formation at current can tell us a bit, but there are still gaps.
One of the best ways to help figure out how the Earth was created is to directly observe other solar systems that are now forming. It will be possible, with telescopes like the future Square Kilometre Array, to directly image proto-planetary disks and make movies over periods of years. These are the disks of dust and gas that form into planetary systems. By observing enough systems, at different stages of formation, we will be able to get an insight into how planets, including like the Earth, form.
Nice answers by Dustin and Steven. 🙂
Yep, I’m not needed here 🙂
By BRIDGE8 under license from Mangorolla CIC 2020