gravity, stars and planets. interstellar cloud where star & solar system formation occurs
TRANSCRIPT
The interstellar cloud pulls together due to gravity, and forms a spinning disc with a young star forming at its center and planets forming in the disc.
Young Star
Planet-forming disc
Young stars surrounded by planet-forming discs in Orion Nebula
(Photos taken using Hubble Space Telescope)
Young Star
Planet-forming disc
Early Solar System: The Sun contracts under gravity and starts burning nuclear fuel; planets grow in size as their gravity sweeps up dust, ice, and gases while they orbit the Sun.
Outer Solar System has more gases and ice, which makes planets more massive.
Round shape guarantees that force of rock pushing up from below exactly balances inward force of gravity.
(A) Bulge lines up with Earth due to Earth’s gravity. (B) Moon tries to rotate bulge away, but Earth pulls it back, causing friction between the bulge and the Moon. (C) Over time, friction slows down the Moon’s rotation, until the bulge always faces Earth.
Orbits of Neptune, Pluto, and Orcus
(a plutino)
Orcus’s period = Pluto’s period = 248 yrs. =
50% longer than Neptune’s period