The asteroid belt is a region of the solar system falling roughly between the planets Mars and Jupiter where the greatest concentration of asteroid orbits can be found.
Despite popular imagery, the asteroid belt is mostly empty.
The asteroids are spread over such a large volume that it would be highly improbable to reach an asteroid without aiming carefully.
Nonetheless, tens of thousands of asteroids are currently known, and estimates of the total number range in the millions.
About 220 of them are larger than 100 km.
The biggest asteroid belt member, and the only dwarf planet found there, is Ceres, which is about 1000 km across.
The total mass of the Asteroid belt is estimated to be 3.0 to 3.6×1021 kilograms, which is 4 percent of the Earth's Moon.
Of that total mass, one third is accounted for by Ceres alone.
The high population makes for a very active environment, where collisions between asteroids occur very often (in astronomical terms).
A collision may fragment an asteroid in numerous small pieces (leading to the formation of a new asteroid family), or may glue two asteroids together if it occurs at low relative speeds.
After five billion years, the current Asteroid belt population bears little resemblance to the original one.
Near-Earth asteroid Near-Earth asteroids (NEAs) are asteroids whose orbits are close to Earth's orbit. Some NEAs' orbits intersect Earth's so they pose a collision ... >
read more
Neptune's natural satellites Neptune has 13 known moons. The largest by far is Triton, discovered by William Lassell just 17 days after the discovery of Neptune itself. It took a ... >
read more
Gas giant A gas giant is a large planet that is not primarily composed of rock or other solid matter. Gas giants may have a rocky or metallic core—in ... >
read more
Dysnomia (moon of Eris) Dysnomia, is a moon of the dwarf planet Eris. The satellite is about 60 times fainter than Eris, and its diameter is estimated to be approximately ... >
read more
Deimos (moon) Deimos is probably an asteroid that was perturbed by Jupiter into an orbit that allowed it to be captured by Mars, though this hypothesis is still in ... >
read more
Near-Earth object Near-Earth objects (NEO) are asteroids, comets and large meteoroids whose orbit intersects Earth's orbit and which may therefore pose a collision ... >
read more
Planet The International Astronomical Union defines "planet" as a celestial body that, within the Solar System that is in orbit around the Sun; has ... >
read more
Uranus' natural satellites Uranus has 27 known moons. The first two moons (Titania and Oberon) were discovered by William Herschel on March 13, 1787. Two more moons (Ariel and ... >
read more
Van Allen radiation belt The Van Allen radiation belt is a torus of energetic charged particles (i.e. a plasma) around Earth, trapped by Earth's magnetic field. When the ... >
read more
Phobos (moon) Phobos is the larger and innermost of Mars' two moons, and is named after Phobos, son of Ares (Mars) from Greek Mythology. Phobos orbits closer to a ... >
read more