A small, irregularly shaped object made of metal (iron and nickel), rocky materials, or a combination of the two that orbits the Sun or another planet. Most of the asteroids orbit in a broad band between the orbits of Mars and Jupiter. The largest is Ceres, which is about 600 miles (900 km) in diameter.


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Asteroids At the dawn of the 19th century, a group of...

Featured Images

Radio view of asteroid 2015 TB145, which will pass close to Earth on Halloween
Boo! Saturday, October 31, 2015
Dawn images of north pole of Ceres
Over the Top Friday, April 17, 2015
A full rotation of Ceres as seen by the Dawn mission
Final Approach Tuesday, March 3, 2015
Dawn image of mysterious bright spots on Ceres, February 19, 2015
Bright Mysteries Thursday, February 26, 2015
Dawn image of Ceres, January 25, 2015
Getting Closer Wednesday, January 28, 2015
A giant asteroid slams into Earth, leading to global extinctions
Impact! Monday, January 6, 2014
Keeping Track Saturday, February 16, 2013
Chart showing the path of asteroid 2012 DA14 relative to Earth.
Getting Close Thursday, February 14, 2013
View of the asteroid Vesta from the Dawn spacecraft
Ready for Departure Thursday, August 23, 2012
Galileo view of Gaspra, the first asteroid visited by a spacecraft
First Encounter Saturday, October 29, 2011
Dawn's first view of Vesta after entering orbit, July 2011
Settling In Monday, July 18, 2011
Dawn spacecraft view of asteroid Vesta shortly before entering orbit
First Stop Friday, July 15, 2011
The path of asteroid 2011 MD as it passes Earth, June 2011
Close Call Saturday, June 25, 2011
Impact! Wednesday, February 3, 2010

Radio Programs

Close Visitors Keeping an eye out for trouble Saturday, October 17, 2015
Oceans Gained Filling up Earth’s oceans Friday, June 5, 2015
Occultations Illumination from darkness Friday, January 23, 2015
Moon and Mars Asteroids take aim at Mars Thursday, January 22, 2015
Asteroid Hunting Pointing the way to two asteroids Sunday, July 13, 2014
Fresh Ideas Looking for fresh ideas Thursday, July 3, 2014
Watery Asteroid Water vapor from a big ball of rock Friday, May 2, 2014
Earth Impacts V Protecting Earth from space rocks Friday, January 10, 2014
Earth Impacts IV Going to work for planetary defense Thursday, January 9, 2014
Quadrantid Meteors Looking for the parent of a meteor shower Thursday, January 2, 2014
Geminid Meteors Feeding a meteor shower Thursday, December 12, 2013
Mars Companions Distant companions for the Red Planet Sunday, December 1, 2013
Asteroid Moons Asteroids with small companions Wednesday, August 28, 2013
Bright Visitors Bright visitors from beyond Earth Monday, April 22, 2013
Messy Impact Debating a devastating impact Wednesday, April 17, 2013
Space Watch IV A very close encounter Thursday, February 14, 2013
Space Watch III Painting our way out of a jam Wednesday, February 13, 2013
Space Watch II Searching for cosmic bullets Tuesday, February 12, 2013
Space Watch A target in a cosmic shooting gallery Monday, February 11, 2013
Apophis Keeping an eye on a troublemaker Tuesday, January 8, 2013
OSIRIS-Rex Studying a threatening space rock Sunday, August 26, 2012
Homeworld Security Tracking down threats from space Saturday, August 25, 2012
Dawn II Piecing together the story of an asteroid Thursday, August 23, 2012
Dawn A witness to the dawn of the solar system Wednesday, August 22, 2012
Space Rocks Rocks from beyond Earth Wednesday, January 18, 2012
Another Encounter Keeping tabs on a rocky visitor Monday, November 7, 2011
Galileo at Gaspra A first encounter with a space rock Saturday, October 29, 2011
NEEMO Diving toward an asteroid Monday, October 17, 2011
Another Close Call A close visit by an asteroid Sunday, October 16, 2011
Dawn at Vesta III An asteroid with a difference Friday, July 15, 2011
Dawn at Vesta II A gentle ride to an asteroid Thursday, July 14, 2011
Close Encounter A neighbor pays Earth a close visit Wednesday, June 1, 2011
Irene Discovering a "peaceful" planetoid Thursday, May 19, 2011
Lutetia Ready to map an asteroid Tuesday, May 3, 2011
Ready for Vesta Ready to map a giant asteroid Monday, May 2, 2011
Taking Inventory II Watching for invaders from beyond Sunday, March 27, 2011
Taking Inventory Taking inventory of the solar system Saturday, March 26, 2011
NEAR Encounter A close encounter with an asteroid Saturday, February 12, 2011


©2015 The University of Texas McDonald Observatory