Origins |
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The Universe has formed, stars have been born, then died. New stars and solar systems can form from the remains of the exploded stars. This process is called the Nebular Hypothesis, and it's the leading theory as to how solar systems form.
Watch this video, The Solar System's Formation. As you do, note the following:
A star explodes and forms a nebula. Then what? The nebula begins to spin. Some parts of the nebula spin a bit faster than the rest. Gravity pulls the heavier elements towards the center, forming a protostar. Swirling around the protostar are the nebular gasses and dust particles. The dust particles start to smash into one another as they orbit around the prostar. As particles continue to collide with one another, they generate friction & heat. Heat makes the particles melt and fuse together, making it easier for the particles to stick together. Thus, larger and larger particles coalesce. The Nebular Hypothesis is the leading hypothesis of how the planets formed: via the accretion of particles.
Click on the image for a larger version. How Did the Solar System Form? Accessible (text only) version
Click on the image for a larger version.
Image source: "How Did the Solar System Form?" by NASA Space Place is in the Public Domain
As particles continue to collide with one another, they generate friction & heat. Heat makes the particles melt and fuse together and larger and larger particles coalesce, eventually forming large bodies - planets.
Thus, all planets formed via the accretion of particles. Initially, all of the planets were:
The image below is an artist's conception of the bombardment of a protoplanet by objects whizzing about the solar system. The website, Nature, has a good article ("Building a planet in record time") on how Mars is thought to have formed.
How old is our solar system? Find out at NASA's "Solar System In-Depth" Page!
Yay! We have planets! Or, do we?
copyright Sonjia Leyva 2022 |
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