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What is the solar system?
Quick answer
The solar system is the Sun and everything bound to it by gravity — eight planets, their moons, dwarf planets, asteroids, and comets. It formed about 4. 6 billion years ago from a collapsing cloud of gas and dust. The Sun holds over 99% of the system's mass and anchors everything in orbit.
Key things to understand
- The Sun holds over 99% of the system's mass and anchors everything in orbit.
- The four inner planets are rocky; the four outer ones are gas and ice giants.
- Smaller bodies — asteroids, comets, dwarf planets like Pluto — orbit too.
- Gravity keeps every object circling the Sun.
People also ask
How many planets are in the solar system?
Eight: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Why isn't Pluto a planet?
In 2006 it was reclassified as a 'dwarf planet' because it hasn't cleared other objects from its orbital path.
What holds the solar system together?
The Sun's gravity, which keeps all the planets and smaller bodies in orbit.
Part of the guide: Space & Astronomy →