A chunk of ice and rock that orbits a star. In our solar system, the majority of comets orbit well beyond Pluto, in regions known as the Kuiper Belt and the Oort Cloud. Most comets are no more than a few miles in diameter. Upon close encounters with the Sun, comet ices vaporize, creating a coma, or cloud, around the comet, and a long tail that always points away from the Sun.


Remnants from the Beginning Whenever you build a new house, you always have...
Comets With the possible exception of Saturn's rings,...

Radio Programs

Doomed Comets Tracking doomed comets — after this. Wednesday, January 20, 2016
Stardust Catching bits of stardust Friday, January 15, 2016
Orionid Meteors Reminders of a distant comet Monday, October 19, 2015
Morning Mercury A dark planet in the dawn sky Saturday, October 10, 2015
Fomalhaut Grinding up some “dusty” comets Monday, September 21, 2015
Oceans Gained Filling up Earth’s oceans Friday, June 5, 2015
Floating Comet Bobbing along with a rubber duckie Friday, March 13, 2015
Ready for Landing Getting ready to land on a comet Sunday, November 2, 2014
Meteor Showers Meteor showers on two planets Saturday, October 18, 2014
Close to Mars II Hiding behind the Red Planet Friday, October 17, 2014
Close to Mars An icy relic takes aim at Mars Thursday, October 16, 2014
Perseid Meteors Looking for sparks through the moonlight Sunday, August 10, 2014
Impact! Cosmic missiles slam into Jupiter Wednesday, July 16, 2014
Surprise Shower? Looking for a new meteor shower Thursday, May 22, 2014
Eta Aquarid Meteors Naming a meteor shower Sunday, May 4, 2014
Watery Asteroid Water vapor from a big ball of rock Friday, May 2, 2014
Stardust Catching bits of comet dust Wednesday, January 1, 2014
Comet Flop A good view of a cometary dud Thursday, December 26, 2013
Geminid Meteors Feeding a meteor shower Thursday, December 12, 2013
Sunward Bound A comet blazes toward the Sun Wednesday, November 27, 2013
Getting Closer A comet streaks toward the Sun Friday, November 1, 2013
Orionid Meteors Moonlight and meteors Sunday, October 20, 2013
Getting Closer Climbing high to see a comet Friday, September 6, 2013
Comet PanStarrs A comet gets ready to shine Monday, March 4, 2013
Bright Interlopers Disorderly visitors head inward Thursday, January 3, 2013
Comets Icy remnants from the birth of the planets Wednesday, January 2, 2013
Orionid Meteors A trail of lights from a messy comet Saturday, October 20, 2012
Comet Swift-Tuttle A famous comet changes its image Wednesday, July 18, 2012
Tuttle Comets War, embezzlement, and comets Tuesday, July 17, 2012
Swift Comets From hardware-store owner to cosmic celebrity Monday, July 16, 2012
Comet Exchange Stars exchange frozen leftovers Friday, June 15, 2012
Watery Earth Raining on the young planet Earth Monday, January 9, 2012
Jean-Louis Pons The champion of all comet hunters Friday, December 23, 2011
Leonid Meteors A faint but steady meteor shower Wednesday, November 16, 2011
Great Comet of 1811, II War, peace, and fine wines Wednesday, November 2, 2011
Great Comet of 1811 A great show by a “dirty snowball” Tuesday, November 1, 2011
Orionid Meteor Shower Calling cards of a distant comet Wednesday, October 19, 2011
Comet Elenin A close encounter with comet dust Friday, October 14, 2011
Star Travels A fanciful design for a starship Sunday, July 24, 2011
Great Comet of 1861 A "fearful" cometary spectacle Thursday, June 30, 2011
Halley's Armada An armada takes aim at Halley's Comet Saturday, March 5, 2011
Comet Encounter Returning to the scene of a wreck Monday, February 14, 2011

Featured Images

View of a doomed comet approaching the Sun
Doomed Comet Wednesday, January 20, 2016
Images of Comet Churyumov-Gerasimenko on August 12
Busy Comet Saturday, August 15, 2015
Rosetta view of Comet Churyumov-Gerasimenko on March 22, 2015
Messy Comet Thursday, April 2, 2015
Rosetta view of Comet Churyumov-Gerasimenko on February 14, 2015
Imhotep Saturday, February 21, 2015
Philae lander view of its landing site
Stuck? Friday, November 14, 2014
View of Philae lander and its target comet
Headed for a Comet Wednesday, November 12, 2014
Artist's concept of Philae lander on Comet 67P/Churyumov–Gerasimenko
Touchdown! Wednesday, November 12, 2014
Artist's concept of Comet Siding Spring approaching Mars
Martian Encounter Thursday, October 16, 2014
October 7 view of Rosetta spacecraft and its target comet
Neighbors Tuesday, October 14, 2014
August 6, 2014, view of Comet Churyumov-Gerasimenko by Rosetta
Getting Closer Thursday, August 7, 2014
August 3, 2014, image of Comet Churyumov-Gerasimenko from Rosetta
Arrival Wednesday, August 6, 2014
Artist's concept of comet impact on Jupiter
Strike One! Wednesday, July 16, 2014
Artist's concept of Rosetta contacting Earth
Back to Work Monday, January 20, 2014
Three views of Comet Kohoutek
Comet Flop Thursday, December 26, 2013
Space station view of Comet ISON and other celestial objects
Doomed Comet Wednesday, December 4, 2013
View of Comets ISON and Encke from a Sun-watching spacecraft
Sizzling Comets Wednesday, November 27, 2013
Hubble Space Telescope view of Comet ISON in October 2013
Getting Closer Friday, October 18, 2013
Hubble Space Telescope view of Comet ISON, May 2013
Closing In Tuesday, July 2, 2013
Hubble Space Telescope image of Comet ISON, April 2013
Closing In Wednesday, April 24, 2013
Comet C/2011 L4 Panstarrs in the western evening sky in March
Sneaky Comet Sunday, March 10, 2013
Comet McNaught, 2007
Bright Interlopers Wednesday, January 2, 2013
Orionid Meteor Shower
Orionid Meteors Saturday, October 20, 2012
False-color view of Comet Swift-Tuttle, 1992
Swift Comet Monday, July 16, 2012
View of Comet Lovejoy from the International Space Station
Christmas Comet Friday, December 23, 2011
A comet plunges toward the Sun
Survivor: Comet Friday, December 16, 2011
Illustration showing the Great Comet of 1861
Great Comet Thursday, June 30, 2011
Giotto spacecraft view of Halley's Comet, March 1986
Halley's Armada Saturday, March 5, 2011
Comet Tempel 1 as seen by the Stardust spacecraft, February 14, 2011
Close Cometary Encounter Thursday, February 17, 2011
Comet Tempel-1 from the Stardust spacecraft, February 14, 2011
Second Glance Tuesday, February 15, 2011
Comet Hartley-2 from Deep Impact Spacecraft
Fowl Comet? Friday, November 5, 2010
Deep Impact view of Comet Hartley-2
Closing In Thursday, November 4, 2010
Comet Hartley-2 from McDonald Observatory
Jolly Green Comet Thursday, October 21, 2010
Infrared view of Comet Hartley 2 from WISE
Heading for a Rendezvous Wednesday, October 6, 2010
Halley's Comet streaks across the sky
Look! It's Halley's Comet! Tuesday, May 11, 2010
Impact! Wednesday, February 3, 2010


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