Asteroid Belt

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American Museum of Natural History (YouTube Channel)


Asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called asteroids or minor planets. It is also called the main asteroid belt to distinguish it from other asteroid populations in the Solar System such as near-Earth asteroids and trojan asteroids. About half its mass is contained in the four largest asteroids: Ceres, Vesta, Pallas, and Hygiea. The total mass of the asteroid belt is about 4% that of the Moon. Ceres, the only object in the asteroid belt large enough to be a dwarf planet, is about 950 km in diameter, whereas Vesta, Pallas, and Hygiea have mean diameters less than 600 km. The remaining bodies range down to the size of a dust particle. — Wikipedia

Asteroid Belt (Encyclopædia Britannica)

Asteroid Belt (Wolfram Alpha)
Minor Planets (Wolfram Alpha)




Dawn was a space probe that was launched by NASA in September 2007 with the mission of studying two of the three known protoplanets of the asteroid belt: Vesta and Ceres. Dawn entered orbit around Vesta on July 16, 2011, and completed a 14-month survey mission before leaving for Ceres in late 2012. It entered orbit around Ceres on March 6, 2015. In 2017, NASA announced that the planned nine-year mission would be extended until the probe’s hydrazine fuel supply was depleted. On November 1, 2018, NASA announced that Dawn had depleted its hydrazine, and the mission was ended. The spacecraft is currently in a derelict, but stable, orbit around Ceres. Dawn is the first spacecraft to orbit two extraterrestrial bodies, the first spacecraft to visit Vesta and Ceres, and the first to orbit a dwarf planet. — Wikipedia

Dawn (NASA Jet Propulsion Laboratory, YouTube Playlist)
Legacy of NASA’s Dawn, Near the End of its Mission (NASA/JPL)
Dawn (JPL, NASA)
Dawn Mission (NASA)




In 1596, Johannes Kepler wrote, “Between Mars and Jupiter, I place a planet,” in his Mysterium Cosmographicum, stating his prediction that a planet would be found there. While analyzing Tycho Brahe’s data, Kepler thought that too large a gap existed between the orbits of Mars and Jupiter to fit Kepler’s then-current model of where planetary orbits should be found.

In an anonymous footnote to his 1766 translation of Charles Bonnet’s Contemplation de la Nature, the astronomer Johann Daniel Titius of Wittenberg noted an apparent pattern in the layout of the planets, now known as the Titius-Bode Law. If one began a numerical sequence at 0, then included 3, 6, 12, 24, 48, etc., doubling each time, and added four to each number and divided by 10, this produced a remarkably close approximation to the radii of the orbits of the known planets as measured in astronomical units, provided one allowed for a “missing planet” (equivalent to 24 in the sequence) between the orbits of Mars (12) and Jupiter (48).

When William Herschel discovered Uranus in 1781, the planet’s orbit matched the law almost perfectly, leading astronomers to conclude that a planet had to be between the orbits of Mars and Jupiter.

On January 1, 1801, Giuseppe Piazzi, chairman of astronomy at the University of Palermo, Sicily, found a tiny moving object in an orbit with exactly the radius predicted by this pattern. He dubbed it “Ceres”, after the Roman goddess of the harvest and patron of Sicily. Piazzi initially believed it to be a comet, but its lack of a coma suggested it was a planet. Thus, the aforementioned pattern predicted the semimajor axes of all eight planets of the time (Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, and Uranus). — Wikipedia

The first asteroid ever discovered (Carrie Nugent, TED-Ed)


WorldCat, Library of Congress, UPenn Online Books, Open Library




Asteroid Belt (Cosmos4Kids)
Planets and Dwarf Planets (Ask an Astronomer, Cornell University)

MERLOT: Multimedia Educational Resource for Learning and Online Teaching
OER Commons: Open Educational Resources



International Astronomical Union (IAU)
Minor Planet Center (International Astronomical Union)


Asteroid Belt (Astronomy Magazine)
Asteroid Belt (
Asteroid Belt (NPR Archives)



Asteroid Belt (




Ripley’s Believe It or Not (YouTube Channel)


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Here are links to pages about closely related subjects.

Knowledge Realm


Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle

Universe (Astronomical Instrument)
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Our Neighborhood
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid


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