The fourth planet from the Sun. Mars orbits the Sun at an average distance of 1.52 times Earth's distance. The planet is about 10 percent as massive as Earth, and a bit more than half as big. It is made of solid, rocky material, and has a thin atmosphere of carbon dioxide. Iron oxide, or rust, on the surface of Mars gives it its characteristic red color. The planet has bright polar ice caps made of frozen water and carbon dioxide. Mars also has two small moons, Phobos and Deimos.


Exploring Our Own Back Yard The four planets closest to the Sun -- Mercury,...
Mars' Moons Two small moons, Phobos and Deimos, orbit Mars....
Mars Mars inspires speculation like no other world in...

Radio Programs

Moon and Mars Warming up a cold planet Saturday, March 21, 2015
Hints of Life Hints of life in more Mars rocks Friday, February 27, 2015
Triple Play II Two very different neighbors Friday, February 20, 2015
Moon and Mars Asteroids take aim at Mars Thursday, January 22, 2015
Moon and Mars Flickering images of a famous world Wednesday, December 24, 2014
Mars at Perihelion Mars gets close to the Sun Saturday, December 13, 2014
Moon and Mars Jet lag after a long trip Tuesday, November 25, 2014
Moon and Mars The planet Mars runs in place Monday, October 27, 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
Mars and Antares Coloring in two bright pinpoints Thursday, September 25, 2014
MAVEN Probing Mars’s escaping atmosphere Sunday, September 21, 2014
The Next Wave A new wave of explorers at Mars Tuesday, September 16, 2014
Supervolcanoes Supervolcanoes on the Red Planet Monday, September 15, 2014
Moon and Planets Ringing out the weekend Sunday, August 31, 2014
Mars and Saturn A new season for the Red Planet Thursday, August 21, 2014
Moon and Mars Coloring the Martian sky Saturday, August 2, 2014
More Moon and Mars A planetary deepfreeze Saturday, June 7, 2014
Moon and Mars Evidence of life in a rock from Mars Friday, June 6, 2014
Moon and Mars Digging holes on other worlds Saturday, May 10, 2014
Loopy Planet A planet gets a little loopy Sunday, April 27, 2014
Mars at Opposition III The hazards of living on Mars Wednesday, April 9, 2014
Mars at Opposition II Catching the sunrise on Mars Tuesday, April 8, 2014
Mars at Opposition Snuggling fairly close to Mars Monday, April 7, 2014
More Moon and Companions Getting close to bright Mars Tuesday, March 18, 2014
Moon and Companions Seeing orange on a nearby planet Monday, March 17, 2014
Old Mars Rock A relic of a bygone era on Mars Sunday, March 16, 2014
Moon and Mars Taking a trip to Mars Tuesday, January 21, 2014
Mars Exploration Rovers Two visitors for the planet Mars Saturday, January 4, 2014
Moon and Companions Sniffing out life on Mars Wednesday, December 25, 2013
Moon and Mars Mars gets a holiday visitor Tuesday, December 24, 2013
Mars Companions Distant companions for the Red Planet Sunday, December 1, 2013
MAVEN The disappearing Martian air Sunday, November 17, 2013
War of the Worlds An attack from Mars Wednesday, October 30, 2013
Moon and Mars A comfortable planetary neighbor Monday, October 28, 2013
Icy Mars Digging into Mars’s frozen past Friday, October 11, 2013
Heading for Mars Streaking down Martian slopes Thursday, October 10, 2013
Mars on Earth Looking for Mars on Earth Wednesday, October 9, 2013
Moon and Companions Warming up a Martian hemisphere Monday, September 30, 2013
Moon and Mars Gentle giants on the planet Mars Sunday, September 29, 2013
Moon and Mars Drilling holes in the surface of Mars Sunday, September 1, 2013
Moon in the Middle The Moon and a bright triangle Saturday, August 31, 2013
Moon and Mars Visitors from other worlds Saturday, December 15, 2012
Moon and Mars Mars hangs out in the evening sky Thursday, November 15, 2012
Zagami Meteorite A startling messenger from Mars Wednesday, October 3, 2012
Moon and Mars Prime real estate on other worlds Wednesday, September 19, 2012
Dune Worlds Giant sand dunes on alien worlds Friday, August 31, 2012
Red Rivals Colorful rivals in the evening sky Wednesday, August 29, 2012
Mars Tales A new visitor and an old myth Friday, August 3, 2012
Moon and Planets Admiring the twilight on another world Tuesday, July 24, 2012
Moon and Mars Listening in to the Red Planet Monday, June 25, 2012
Storm Season Stirring up cold fronts on Mars Saturday, March 31, 2012
Summertime The good old summertime Friday, March 30, 2012
Racing Ahead Racing the Red Planet around the Sun Friday, March 16, 2012
Comfy Planets Looking for comfy homes for life Sunday, March 4, 2012
Mars at Opposition Drawing a map of the solar system Saturday, March 3, 2012
Secret Mars Unlocking the secrets of the Red Planet Friday, March 2, 2012
Mars Mayhem Mars marches across March skies Thursday, March 1, 2012
Warming Mars Warming up a desert planet Sunday, February 19, 2012
More Moon and Mars Scaling the heights of Mars Friday, January 13, 2012
Moon and Mars Watery oases on a desert world Thursday, January 12, 2012
Moon and Mars Molding the image of the Red Planet Friday, December 16, 2011
Mars Science Laboratory III Protecting Mars from alien invaders Thursday, November 24, 2011
Mars Science Laboratory II Sniffing out life on Mars Wednesday, November 23, 2011
Mars Science Laboratory I Plumbing for water on Mars Tuesday, November 22, 2011
More Moon and Companions Settling in on a new world Friday, November 18, 2011
Moon and Companions Spacing out a morning lineup Thursday, November 17, 2011
Mars and Regulus Two old friends in the morning sky Thursday, November 10, 2011
Back in the Game? Staging a return to deep space Thursday, November 3, 2011
Moon and Mars Strolling on alien worlds Thursday, October 20, 2011
Moon and Mars Twin moons under alien skies Thursday, September 22, 2011
More Moon and Jupiter Jumpin' Jupiter! Saturday, August 20, 2011
Hardy Bacteria Grinding up rocks to hunt for life Friday, July 29, 2011
Rock Varnish Polishing some Martian rocks Wednesday, July 27, 2011
Moon and Mars Looking for Mars-on-Earth Tuesday, July 26, 2011
Gassy Mars The "gassy" Martian atmosphere Wednesday, June 29, 2011
More Moon and Mars Mars falls on an Egyptian village Tuesday, June 28, 2011
Moon and Mars Greening up the Red Planet Monday, June 27, 2011
Watery Mars Divining for water on Mars Thursday, April 14, 2011
Mars in Conjunction Hiding in the bright sunshine Thursday, February 3, 2011
Moon and Companions Standing between a pair of rivals Sunday, October 10, 2010
Life in the Solar System Looking for life in all the right places Tuesday, September 7, 2010
Family Reunion A family reunion in the evening sky Sunday, August 1, 2010
Moon and Mars Blowing across an alien landscape Thursday, July 15, 2010
Weather "Weathering" the solar system Monday, July 12, 2010
More Moon and Companions Picking up rocks from Mars Thursday, June 17, 2010
Moon and Companions Picking blueberries...on Mars Wednesday, June 16, 2010
Mars and Regulus II Stripping away the Martian atmosphere Monday, June 7, 2010
Mars and Regulus A planet speeds across the sky Sunday, June 6, 2010
Lasers III Getting back at Mars Wednesday, May 19, 2010
More Moon and Mars Projecting a new image for Mars Thursday, March 25, 2010
Moon and Mars Just talking about the weather Wednesday, March 24, 2010
Giovanni Schiaparelli Digging up Martian canals Sunday, March 14, 2010
Moon and Mars Full Moon, full Mars Friday, January 29, 2010
Martian Air Pondering the fate of the Martian atmosphere Thursday, January 28, 2010
Journey to Mars Packing up for a trip to Mars Wednesday, January 27, 2010
Extreme Mars Highs and lows on the Red Planet Tuesday, January 26, 2010
Mars Looking in on a close neighbor Monday, January 25, 2010

Featured Images

Curiosity rover view of rock layers inside Gale Crater on Mars
Ancient Lakebed Tuesday, December 9, 2014
Artist's concept of Comet Siding Spring approaching Mars
Martian Encounter Thursday, October 16, 2014
India's Mars Orbiter Mission
On Target Again Wednesday, September 24, 2014
Artist's concept of MAVEN orbiting MARS
On Target Saturday, September 20, 2014
September 9, 2014, view of Curiosity rover's surroundings on Mars
Going Strong Tuesday, September 9, 2014
Artist's concept of early morning fog, clouds, and frost on Mars
Morning Fog Tuesday, April 8, 2014
Downhill Racer Saturday, February 22, 2014
Fresh Martian impact crater seen by an orbiting spacecraft in late 2013
Fresh Impact Friday, February 7, 2014
Artist's concept of a Mars Exploration Rover landing on Mars in 2004
Follow the Bouncing Rover Saturday, January 4, 2014
Launch of MAVEN spacecraft to Mars
On Its Way Monday, November 18, 2013
Almost Ready Monday, November 18, 2013
Artist's concept of MAVEN Mars orbiter
Mars Maven Sunday, November 17, 2013
Rio Tinto, a river in Spain, is a Mars analog
Red River Wednesday, October 9, 2013
Kasei Valles, an ancient flood channel on Mars
Ancient Flood Monday, June 10, 2013
Curiosity rover view of Mount Sharp, March 2013
Sharp Destination Tuesday, March 19, 2013
Self-portrait of Curiosity rover on Mars, February 2013
Self-Portrait Monday, February 18, 2013
Curiosity view of Rocknest on Mars
Rocky Home Thursday, November 29, 2012
Recent image from Mars rovers Curiosity and Opportunity
Mars Targets Saturday, September 29, 2012
Early view of the rim of Gale Crater
Inside the Wall Sunday, August 12, 2012
Mars Science Laboratory heatshield falls away
Martian Litter Friday, August 10, 2012
August 8, 2012, view of Mars from the Curiosity rover
Getting Acquainted Wednesday, August 8, 2012
Composite view of Curiosity rover landing and operating on Mars
Drop In, Stay Awhile Monday, August 6, 2012
Artist's concept of Mars Science Laboratory approaching the Red Planet
Final Approach Friday, August 3, 2012
Mars is at opposition in early March 2012, shining brightest for the year
Mighty Mars Saturday, March 3, 2012
Endeavour Crater, winter home of the Opportunity Mars rover
Winter Wonderland Thursday, January 26, 2012
Artist's concept of Curiosity rover on Mars
Ready to Roll Wednesday, November 23, 2011
The Russian Phobos-Grunt Mars mission launches on November 8, 2011
Phobos Flop? Friday, November 11, 2011
Craters fill an ancient river channel on Mars
Martian Rapids Monday, October 10, 2011
Panoramic view of Endeavour crater on Mars, imaged by the Opportunity rover
Final Destination Thursday, August 11, 2011
Possible rivulets of water flowing on Mars
Drippy Planet Monday, August 8, 2011
Rock varnish on a rock from the Atacama Desert
Bacteria Colony? Friday, July 29, 2011
Scientists are studying rocks in Chile to learn about possible life on Mars
Looking for Life Wednesday, July 27, 2011
Chile's Atacama Desert is an analog for studying conditions on Mars
Mars on Earth Tuesday, July 26, 2011
The Opportunity rover crosses the Martian plains toward Endeavour crater
Crater Crawling Saturday, April 16, 2011
Image of water distribution in northern hemisphere of Mars
Watery Mars Thursday, April 14, 2011
Ground and orbital views of Opportunity rover at Santa Maria crater
Looking In Tuesday, February 8, 2011
Opportunity rover view of Santa Maria crater
Crater Climbing Thursday, December 30, 2010
A thick dust storm blows across Mars in this image from Mars orbit.
Dusty Skies Monday, July 12, 2010
The next Mars rover, Curiosity, zaps a Martian rock with a small laser in this a
War of the Worlds? Wednesday, May 19, 2010
Martian 'Canali' Sunday, March 14, 2010
Bright Encounter Wednesday, January 27, 2010


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