Comet
From Simple English Wikipedia, the free encyclopedia
A comet is a ball of mostly ice that moves around in outer space. It is similar to an asteroid. In Earth's solar system, the orbits of comets go farther than Pluto, a dwarf planet that used to be the farthest planet from the Sun. Most are very far away from the Sun, but some come near enough to Earth for us to see at night. They have long "tails", because the Sun melts the ice. Sometimes people call them "dirty snowballs" or "shooting stars".
The hard centre of the comet is the nucleus. It is one of the blackest things in the solar system. When light shone on Comet Halley's nucleus, only 4% of the light shone back to us.
Periodic comets visit us again and again. Non-periodic or single-apparition comets visit us only once.
People have seen some comets when they broke into pieces: Comet Biela was one example. Another comet was seen when it hit a planet: Comet Shoemaker-Levy 9 hit Jupiter in 1994. Some comets orbit (go around) together in groups, and astronomers think they are broken pieces that used to be one object.
Some famous comets include:
- Halley's Comet
- Hale-Bopp
- Shoemaker-Levy 9
[edit] See also
| The Solar System | |
|---|---|
| Star | The Sun |
| Planets | Mercury • Venus • Earth • Mars • Jupiter • Saturn • Uranus • Neptune |
| Dwarf planets | Ceres • Pluto • Eris |
| Small solar system body | Asteroid belt – Comets – Meteors – Kuiper belt – Scattered disc – Oort cloud |
| Other | Moon |
