What Are All the Planets?


Quick Answer

The eight planets of the solar system are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The four inner planets are terrestrial worlds, while the outer solar system consists of four gas giants sometimes known as the Jovian planets.

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Full Answer

The four terrestrial planets are much smaller than the gas giants, and each has a solid surface. The outer planets are gas giants, which are made up primarily of hydrogen and helium and lack a clearly defined surface to serve as a boundary between the atmosphere and the inner regions of each planet. Unlike the planets of the inner solar system, the outer planets each have a complex system of rings, as well as multiple moons.

All of the planets were created billions of years ago during the formation of the solar system. The solar system was once a vast cloud of dust and gas that began to collapse under its own weight, forming a large spinning disk. The planets were formed during millions of years as the dust, gas and other particles within this disk collided to form larger and larger objects. With the aid of powerful telescopes, astronomers have been able to discover many planets that exist outside of the solar system.

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