Space Encyclopedia
🪐 The Solar System
Overview
The Solar System is the gravitationally bound collection of the Sun and everything that orbits it — eight planets, five recognized dwarf planets, hundreds of moons, and countless asteroids and comets. The Sun contains 99.86% of the system's mass and drives the solar wind that shapes every planet's space environment.
Key facts
- •Age: ~4.6 billion years
- •Star: The Sun (G-type main sequence)
- •Planets: 8 (Mercury through Neptune)
- •Dwarf planets: 5 recognized (Ceres, Pluto, Haumea, Makemake, Eris)
- •Heliosphere radius: ~120 AU
Why it matters
Every planet sits inside the Sun's extended atmosphere — the heliosphere. Understanding the Solar System's structure is how we predict which storms reach Earth, when Mars missions face danger, and how the outer worlds behave.
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Frequently asked questions
How many planets are in the Solar System?
Eight: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto was reclassified as a dwarf planet in 2006.
What holds the Solar System together?
The Sun's gravity. It accounts for 99.86% of the system's total mass, so every planet, moon, comet, and asteroid orbits it.
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