Asteroid

An asteroid is a small, solid object in our Solar System, orbiting the Sun. An asteroid is an example of a minor planet (or planetoid), which are much smaller than planets. Most asteroids are believed to be remnants of the protoplanetary disc which were not incorporated into planets during the system's formation. Some asteroids have moons. The vast majority of the asteroids are within the main asteroid belt, with elliptical orbits between those of Mars and Jupiter.

Asteroids in Earth's Solar System

Hundreds of thousands of asteroids have been discovered within Earth's solar system. As of September 18, 2005, from a total of 288,683 minor planets with calculated orbits, 99,947 asteroids had been calculated well enough to be given official numbers and 12,639 of these had been officially named (610 of which have names requiring diacriticals). The lowest-numbered but unnamed minor planet is (3360) 1981 VA; the highest-numbered and named minor planet is 99942 Apophis http://cfa-www.harvard.edu/iau/lists/NumberedMPs95001.html.

Related Topics:
September 18 - 2005 - (3360) 1981 VA - 99942 Apophis

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Current estimates put the total number of asteroids in the solar system at several million. The largest asteroid in our inner solar system is 1 Ceres, with a diameter of 900-1000 km. Two other large asteroids are 2 Pallas and 4 Vesta; both have diameters of ~500 km. Vesta is the only main belt asteroid that is sometimes visible to the naked eye (in some very rare occasions, a near-Earth asteroid may be visible without technical aid; see 99942 Apophis).

Related Topics:
1 Ceres - 2 Pallas - 4 Vesta - 99942 Apophis

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The mass of all the asteroids of the Main Belt is estimated to be about 2.3x1021 kg, or about 3% of the mass of our moon. Of this, 1 Ceres comprises 940 to 950x1018 kg, some 40% of the total. Adding in the next three most massive asteroids, 4 Vesta (12%), 2 Pallas (9%), and 10 Hygiea (4%), bring this figure up 66%; while the three after that, 511 Davida (1.6%), 704 Interamnia (1.4%), and 3 Juno (1.2%), only add another 4% to the total mass. The number of asteroids then increases exponentially as their individual masses decrease.

Related Topics:
1 Ceres - 4 Vesta - 2 Pallas - 10 Hygiea - 511 Davida - 704 Interamnia - 3 Juno - Exponentially

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See also a List of noteworthy asteroids in our Solar System, or a sequentially-ordered List of asteroids.

Related Topics:
List of noteworthy asteroids - List of asteroids

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