Planets

In-depth, individual pages in this category.

• Mercury

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  The smallest planet, closest to the Sun.

• Venus

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  Earth's size, but a scorching greenhouse world.

• Earth

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  The third planet — and the only known home of life.

• Mars

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  The Red Planet, a cold desert world.

• Jupiter

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  The largest planet — a banded gas giant.

• Saturn

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  The ringed gas giant.

• Uranus

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  The sideways-spinning ice giant.

• Neptune

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  The deep-blue, windy ice giant at the edge.

Overview

A planet, as defined by the International Astronomical Union, orbits the Sun, is massive enough to be rounded by its own gravity, and has cleared its orbital neighborhood. Our Solar System has eight.

We continue to expand this category. Upcoming material includes:

• The eight planets
• Terrestrial vs. giant planets
• Planetary atmospheres
• Rings and moons

Frequently asked

What is Planets?

A planet, as defined by the International Astronomical Union, orbits the Sun, is massive enough to be rounded by its own gravity, and has cleared its orbital neighborhood. Our Solar System has eight.

Is Planets astronomy or astrology?

Planets is part of astronomy — the evidence-based, scientific study of the universe. On Asteria Star, astronomy is kept clearly separate from astrology.