An asteroid is a space rock. It is a small object in the Solar System that travels around the Sun. It is like a planet but smaller. They range from very small (smaller than a car) to 600 miles (1000 km) across. A few asteroids have asteroid moon.
The name "asteroid" means "like a star" in the ancient Greek language. Asteroids may look like small stars in the sky, but they really do move around the Sun, while stars only seem to move because the Earth spins. Like planets, asteroids do not make their own light. Because of this, some people think "asteroids" is not a good name, and think that the name "planetoid" ("like a planet") would be a better name.
Giuseppe Piazzi found the first asteroid, in 1801. He called it Ceres, and it is the biggest object in the asteroid belt. Others, like Juno, Pallas, and Vesta were found later. In the 1850s so many had been found, that they were numbered by a Minor planet designation starting with 1 Ceres. Today, astronomers using computerized telescopes find thousands of asteroids every month. Asteroid impact prediction is one of the purposes.
Asteroids are the leftover rock and other material from the formation of the Solar System. These rocks were too small to come together to make a planet. Some are made of carbon or metal. Depending on what's on the surface, they are classified into various asteroid spectral types including Type M (metal), Type S (stone), and Type C (carbon).
Most asteroids in our Solar System are in the asteroid belt between Mars and Jupiter. Many are not in the main asteroid belt. The ones that come close to Earth are called Near-Earth asteroids. Many scientists think asteroids striking the Earth killed off all the dinosaurs and caused some of the other extinction events.
|The Solar System
Image:Solar System Template Final.png
- The Sun
rect 0 0 90 35 The Sun
circle 112 18 6 Mercury
circle 153 18 8 Venus
- Earth and the Moon
circle 203 8 4 The Moon
circle 194 18 8 Earth
- Mars and satellites
circle 233 18 8 Mars
circle 239 13 3 Phobos and Deimos
- Ceres and the asteroid belt
- - by placing the rectangle code for the asteroid belt AFTER Ceres, Ceres is "on top" (and can co-exist)
circle 271 18 8 Ceres
rect 256 0 288 35 The main asteroid belt
- Jupiter and satellites
- - by placing the rectangle code for the Rings of Jupiter AFTER Jupiter, Jupiter is "on top" (and can co-exist)
circle 317 18 15 Jupiter
circle 329 5 6 Moons of Jupiter
rect 298 15 335 20 Rings of Jupiter
- Saturn and satellites
- - by placing the rectangle code for the Rings of Saturn AFTER Saturn, Saturn is "on top" (and can co-exist)
circle 372 18 12 Saturn
circle 381 7 6 Moons of Saturn
rect 353 5 389 31 Rings of Saturn
- Uranus and satellites
- - by placing the rectangle code for the Rings of Uranus AFTER Uranus, Uranus is "on top" (and can co-exist)
circle 418 18 12 Uranus
circle 427 10 6 Moons of Uranus
rect 408 4 429 34 Rings of Uranus
- Neptune and satellites
- - by placing the rectangle code for the Rings of Neptune AFTER Neptune, Neptune is "on top" (and can co-exist)
circle 462 18 12 Neptune
circle 471 10 3 Moons of Neptune
rect 441 9 485 28 Rings of Neptune
- Pluto, satellites, and the Kuiper belt
- - by placing the rectangle code for the Kuiper belt AFTER Pluto, Pluto is "on top" (and can co-exist)
circle 504 18 8 Pluto
circle 508 13 3 Moons of Pluto
- Haumea and satellites
- - by placing the rectangle code for the Kuiper Belt AFTER Haumea, Haumea is "on top" (and can co-exist)
circle 534 18 8 Haumea
circle 538 13 3 Moons of Haumea
- - by placing the rectangle code for the Kuiper Belt AFTER Makemake, Makemake is "on top" (and can co-exist)
circle 567 18 8 Makemake
rect 490 0 580 35 The Kuiper Belt
- Eris, Dysnomia, and the Scattered disc
- - by placing the rectangle code for the Scattered disc AFTER Eris, Eris is "on top" (and can co-exist)
circle 596 18 8 Eris
circle 600 14 3 Dysnomia
rect 581 0 610 35 The Scattered Disc
rect 623 0 640 35 The Hills Cloud
rect 641 0 666 35 The Oort Cloud
- - setting this to "bottom-right" will display a (rather large) icon linking to the graphic, if desired
- Details on the new coding for clickable images is here: 
- The smaller planets have a bit of an overlap just to ensure they're locatable, especially in the belts.
- While it may look strange, it's important to keep the codes for a particular system in order. The clickable coding treats the first object created in an area as the one on top.
- - I've placed moons on "top" so that their smaller circles won't disappear "under" their respective planets or dwarf planets.
- The "poly" code would be more appropriate for the moons of Jupiter, Saturn, and Uranus. However, there appears to be a bug with that aspect of the code.
- - I've compensated by using oversized circles for those moon groups, and tucking them UNDER their planets for now.
- The Sun is a rectangle as that approximates the edge closely enough for the purposes of this template.
- I've guessed as to the boundaries for the KB, SD, and OC - if they need adjustment, load the image into Paint and use the pencil tool to find the appropriate coordinates.
☾ = moon(s) ∅ = rings
|| Earth ☾
|| Mars ☾
| Jupiter ☾ ∅
|| Saturn ☾ ∅
|| Uranus ☾ ∅
|| Neptune ☾ ∅
|| Pluto ☾
|| Haumea ☾
| Eris ☾
| Groups and families: Vulcanoids · Near-Earth asteroids · Asteroid belt |
Jupiter Trojans · Centaurs · Neptune Trojans · Asteroid moons · Meteoroids · Pallas · Juno · Vesta · Hygiea · Interamnia · Europa
|See also the list of asteroids.
|Kuiper belt – Plutinos: Orcus · Ixion – Cubewanos: Varuna · |
Quaoar · Huya
| Scattered disc: Sedna
|| Periodic comets and non-periodic comets |
Damocloids · Oort cloud
| See also the list of solar system objects