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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.


Craters and Extinctions February 19, 2016


Asteroids February 19, 2016

Radio Programs

Looking Deep Looking into the hearts of planets March 21, 2017

Time Machine Traveling to the early solar system March 20, 2017

Centaurs Hybrid critters in the outer solar system February 15, 2017

Early Test Looking for asteroids in Earth’s orbit February 8, 2017

Scary Asteroids Cataloging scary space rocks January 15, 2017

Bright Invaders A bright cosmic invasion October 3, 2016

OSIRIS-Rex II Keeping an eye on a potential killer September 7, 2016

OSIRIS-Rex Digging into some leftovers September 6, 2016

Gaspra A breakup creates a big family July 30, 2016

Close Visitors Keeping an eye out for trouble October 16, 2015

Oceans Gained Filling up Earth’s oceans June 4, 2015

Occultations Illumination from darkness January 22, 2015

Moon and Mars Asteroids take aim at Mars January 21, 2015

Asteroid Hunting Pointing the way to two asteroids July 12, 2014

Fresh Ideas Looking for fresh ideas July 2, 2014

Watery Asteroid Water vapor from a big ball of rock May 1, 2014

Earth Impacts V Protecting Earth from space rocks January 9, 2014

Earth Impacts IV Going to work for planetary defense January 8, 2014

Quadrantid Meteors Looking for the parent of a meteor shower January 1, 2014

Geminid Meteors Feeding a meteor shower December 11, 2013

Mars Companions Distant companions for the Red Planet November 30, 2013

Asteroid Moons Asteroids with small companions August 27, 2013

Bright Visitors Bright visitors from beyond Earth April 21, 2013

Messy Impact Debating a devastating impact April 16, 2013

Space Watch IV A very close encounter February 13, 2013

Space Watch III Painting our way out of a jam February 12, 2013

Space Watch II Searching for cosmic bullets February 11, 2013

Space Watch A target in a cosmic shooting gallery February 10, 2013

Apophis Keeping an eye on a troublemaker January 7, 2013

OSIRIS-Rex Studying a threatening space rock August 25, 2012

Homeworld Security Tracking down threats from space August 24, 2012

Dawn II Piecing together the story of an asteroid August 22, 2012

Dawn A witness to the dawn of the solar system August 21, 2012

Space Rocks Rocks from beyond Earth January 17, 2012

Featured Images

Artist's concepts of Lucy, Psyche asteroid missions

Time Machines March 20, 2017

Artist's concept of 2016 WF9

Heading In January 1, 2017

Galileo view of the asteroid Gaspra

First Look July 30, 2016

Radio view of asteroid 2015 TB145, which will pass close to Earth on Halloween

Boo! October 31, 2015

Dawn images of north pole of Ceres

Over the Top April 17, 2015

A full rotation of Ceres as seen by the Dawn mission

Final Approach March 3, 2015

Dawn image of mysterious bright spots on Ceres, February 19, 2015

Bright Mysteries February 26, 2015

Dawn image of Ceres, January 25, 2015

Getting Closer January 28, 2015

A giant asteroid slams into Earth, leading to global extinctions

Impact! January 6, 2014

Keeping Track February 16, 2013

Chart showing the path of asteroid 2012 DA14 relative to Earth.

Getting Close February 14, 2013

View of the asteroid Vesta from the Dawn spacecraft

Ready for Departure August 23, 2012

Galileo view of Gaspra, the first asteroid visited by a spacecraft

First Encounter October 29, 2011

Dawn's first view of Vesta after entering orbit, July 2011

Settling In July 18, 2011

Dawn spacecraft view of asteroid Vesta shortly before entering orbit

First Stop July 15, 2011

The path of asteroid 2011 MD as it passes Earth, June 2011

Close Call June 25, 2011

Impact! February 3, 2010