Our solar system
Began nearly 5 billion years ago.
Our solar system formed from an interstellar cloud. The cloud collapsed, by gravity, flattened, and maintained its swirling motion.
Near our sun-to-be, other pockets of dust and gas stirred up by turbulence within the cloud, began by gravity, to accumulate material. For 10 million years, tiny solid particles grew like colliding snowballs into billions of chunks called planetesimals - the building blocks of planets. For 100 million years the planetesimals collided and formed protoplanets. The remaining debris (meteoroids) bombarded the planets for the next 600 million years.
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Birth of our sun With 99% of the cloud's mass concentrated at its center, this dense core heated up to over a million degrees. At those temperatures, nuclear fusion occurred; our Sun began to shin |
Planets: Failed stars
All around other would-be-stars struggled to reach the proper size. As the Sun's solar wind swept away remaining gas and dust from space, these potential stars remained too small to generate a sustained nuclear reaction and did not shine; they become our planets.
