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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.


Mars' Moons February 19, 2016


Mars February 10, 2016

Radio Programs

Moon and Mars More water on two nearby worlds December 12, 2017

Moon and Mars Making moons over and over again November 14, 2017

Moon and Mars A long period of quiet on Mars October 16, 2017

Mars Returns Stepping toward the Red Planet September 15, 2017

Looking for Canals II Sensational reports from Mars August 4, 2017

Looking for Canals Looking for Martian canals August 3, 2017

Mars Pathfinder Blazing a path on the Red Planet July 4, 2017

Martian Spring Springing into a new season May 5, 2017

Moon and Mars Looking for “gassy” microbes on Mars March 30, 2017

Moon and Planets Climbing through Martian history February 28, 2017

More Moon and Planets Digging up Martian ice January 31, 2017

Moon and Planets Too hot, too cold, and just right January 30, 2017

Moon and Mars Drying out some Martian gullies November 5, 2016

More ExoMars A dress rehearsal for a Mars rover October 17, 2016

ExoMars Lining up an approach to Mars October 16, 2016

Moon and Mars Making ice on a warming planet October 7, 2016

More Moon and Planets Variety in the evening sky October 6, 2016

H.G. Wells Creating an alien invasion September 21, 2016

Mars and Antares Rivals line up in the evening sky August 23, 2016

Martian Tsunami Churning up the Martian ocean August 3, 2016

Moon and Mars Boiling up an avalanche July 13, 2016

Moon and Mars Heating up the Red Planet June 16, 2016

Mars Opposition V Seeing things on the Red Planet — after this. May 22, 2016

Mars Opposition IV Lining up the Red Planet May 21, 2016

Mars Opposition III Living on Mars — sort of May 20, 2016

Mars Opposition II Stripping away the Martian atmosphere May 19, 2016

Mars Opposition A planet makes its own skin crawl May 18, 2016

Moon and Planets A beautiful morning quartet April 24, 2016

Moon and Mars A familiar yet alien world April 23, 2016

Moon and Mars Some of the last Martian lakes March 27, 2016

Heading for Mars Getting ready for a trip to Mars March 11, 2016

Moon and Mars A neighbor world gets brighter February 28, 2016

Moon and Mars Breaking up a small moon January 31, 2016

Cloudy Skies Cloudy skies across the solar system December 27, 2015

Moon and Mars A frozen treat on the Red Planet December 4, 2015

Venus and Mars Planets huddle close in the dawn sky November 1, 2015

Moon and More Companions Filling up a Martian crater October 7, 2015

Morning Lineup Bright lights in the dawn sky September 23, 2015

Moon, Venus, and Mars Ancient Mars cools off September 8, 2015

Shergotty A piece of Mars falls from the sky August 24, 2015

More Mariner 4 Changing the concept of Mars July 13, 2015

Mariner 4 Getting the first good look at Mars July 12, 2015

Martian Methane Tracking down Martian methane June 22, 2015

Martian Spring Wild seasons on the Red Planet June 17, 2015

Ocean Lost A massive ocean on the planet Mars June 3, 2015

Moon and Mars Warming up a cold planet March 20, 2015

Hints of Life Hints of life in more Mars rocks February 26, 2015

Triple Play II Two very different neighbors February 19, 2015

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

Moon and Mars Flickering images of a famous world December 23, 2014

Mars at Perihelion Mars gets close to the Sun December 12, 2014

Moon and Mars Jet lag after a long trip November 24, 2014

Moon and Mars The planet Mars runs in place October 26, 2014

Meteor Showers Meteor showers on two planets October 17, 2014

Close to Mars II Hiding behind the Red Planet October 16, 2014

Close to Mars An icy relic takes aim at Mars October 15, 2014

Mars and Antares Coloring in two bright pinpoints September 24, 2014

MAVEN Probing Mars’s escaping atmosphere September 20, 2014

The Next Wave A new wave of explorers at Mars September 15, 2014

Supervolcanoes Supervolcanoes on the Red Planet September 14, 2014

Moon and Planets Ringing out the weekend August 30, 2014

Mars and Saturn A new season for the Red Planet August 20, 2014

Moon and Mars Coloring the Martian sky August 1, 2014

More Moon and Mars A planetary deepfreeze June 6, 2014

Moon and Mars Evidence of life in a rock from Mars June 5, 2014

Moon and Mars Digging holes on other worlds May 9, 2014

Loopy Planet A planet gets a little loopy April 26, 2014

Mars at Opposition III The hazards of living on Mars April 8, 2014

Mars at Opposition II Catching the sunrise on Mars April 7, 2014

Mars at Opposition Snuggling fairly close to Mars April 6, 2014

More Moon and Companions Getting close to bright Mars March 17, 2014

Moon and Companions Seeing orange on a nearby planet March 16, 2014

Old Mars Rock A relic of a bygone era on Mars March 15, 2014

Moon and Mars Taking a trip to Mars January 20, 2014

Mars Exploration Rovers Two visitors for the planet Mars January 3, 2014

Moon and Companions Sniffing out life on Mars December 24, 2013

Moon and Mars Mars gets a holiday visitor December 23, 2013

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

MAVEN The disappearing Martian air November 16, 2013

War of the Worlds An attack from Mars October 29, 2013

Moon and Mars A comfortable planetary neighbor October 27, 2013

Icy Mars Digging into Mars’s frozen past October 10, 2013

Heading for Mars Streaking down Martian slopes October 9, 2013

Mars on Earth Looking for Mars on Earth October 8, 2013

Moon and Companions Warming up a Martian hemisphere September 29, 2013

Moon and Mars Gentle giants on the planet Mars September 28, 2013

Moon and Mars Drilling holes in the surface of Mars August 31, 2013

Moon in the Middle The Moon and a bright triangle August 30, 2013

Moon and Mars Visitors from other worlds December 14, 2012

Moon and Mars Mars hangs out in the evening sky November 14, 2012

Zagami Meteorite A startling messenger from Mars October 2, 2012

Moon and Mars Prime real estate on other worlds September 18, 2012

Dune Worlds Giant sand dunes on alien worlds August 30, 2012

Red Rivals Colorful rivals in the evening sky August 28, 2012

Mars Tales A new visitor and an old myth August 2, 2012

Moon and Planets Admiring the twilight on another world July 23, 2012

Moon and Mars Listening in to the Red Planet June 24, 2012

Storm Season Stirring up cold fronts on Mars March 30, 2012

Summertime The good old summertime March 29, 2012

Racing Ahead Racing the Red Planet around the Sun March 15, 2012

Comfy Planets Looking for comfy homes for life March 3, 2012

Mars at Opposition Drawing a map of the solar system March 2, 2012

Secret Mars Unlocking the secrets of the Red Planet March 1, 2012

Mars Mayhem Mars marches across March skies February 29, 2012

Warming Mars Warming up a desert planet February 18, 2012

More Moon and Mars Scaling the heights of Mars January 12, 2012

Moon and Mars Watery oases on a desert world January 11, 2012

Featured Images

Opportunity rover view of its surroundings on Mars, June 2017

On the Downslope July 24, 2017

Curiosity rover view of Mars, February 10, 2017

Mountain Climbing February 28, 2017

Before and after views of the landing site of the Schiaparelli probe

Lost and Found October 22, 2016

The ExoMars 2016 mission approaches the Red Planet

Two for Mars? October 17, 2016

A Day on Mars August 24, 2016

Close Neighbor May 20, 2016

Volcanoes on Tharsis Ridge, Mars

Shifting Skin May 18, 2016

ExoMars 2016 launch

Mars Bound March 14, 2016

The Arda Valles region of Mars

Red Tides February 19, 2016

Sand dunes on Mars

Dune World December 20, 2015

Cold Red Planet September 9, 2015

First Eyes on Mars July 13, 2015

Sunset at Gale Crater, Mars, April 2015

Blue Skies May 14, 2015

Curiosity rover view of rock layers inside Gale Crater on Mars

Ancient Lakebed December 9, 2014

Artist's concept of Comet Siding Spring approaching Mars

Martian Encounter October 16, 2014

India's Mars Orbiter Mission

On Target Again September 24, 2014

Artist's concept of MAVEN orbiting MARS

On Target September 20, 2014

September 9, 2014, view of Curiosity rover's surroundings on Mars

Going Strong September 9, 2014

Artist's concept of early morning fog, clouds, and frost on Mars

Morning Fog April 8, 2014

Downhill Racer February 22, 2014

Fresh Martian impact crater seen by an orbiting spacecraft in late 2013

Fresh Impact February 7, 2014

Artist's concept of a Mars Exploration Rover landing on Mars in 2004

Follow the Bouncing Rover January 4, 2014

Launch of MAVEN spacecraft to Mars

On Its Way November 18, 2013

Almost Ready November 18, 2013

Artist's concept of MAVEN Mars orbiter

Mars Maven November 17, 2013

Rio Tinto, a river in Spain, is a Mars analog

Red River October 9, 2013

Kasei Valles, an ancient flood channel on Mars

Ancient Flood June 10, 2013

Curiosity rover view of Mount Sharp, March 2013

Sharp Destination March 19, 2013

Self-portrait of Curiosity rover on Mars, February 2013

Self-Portrait February 18, 2013

Curiosity view of Rocknest on Mars

Rocky Home November 29, 2012

Recent image from Mars rovers Curiosity and Opportunity

Mars Targets September 29, 2012

Early view of the rim of Gale Crater

Inside the Wall August 12, 2012

Mars Science Laboratory heatshield falls away

Martian Litter August 10, 2012

August 8, 2012, view of Mars from the Curiosity rover

Getting Acquainted August 8, 2012

Composite view of Curiosity rover landing and operating on Mars

Drop In, Stay Awhile August 6, 2012

Artist's concept of Mars Science Laboratory approaching the Red Planet

Final Approach August 3, 2012

Mars is at opposition in early March 2012, shining brightest for the year

Mighty Mars March 3, 2012

Endeavour Crater, winter home of the Opportunity Mars rover

Winter Wonderland January 26, 2012

Artist's concept of Curiosity rover on Mars

Ready to Roll November 23, 2011

The Russian Phobos-Grunt Mars mission launches on November 8, 2011

Phobos Flop? November 11, 2011

Craters fill an ancient river channel on Mars

Martian Rapids October 10, 2011

Panoramic view of Endeavour crater on Mars, imaged by the Opportunity rover

Final Destination August 11, 2011

Possible rivulets of water flowing on Mars

Drippy Planet August 8, 2011

Rock varnish on a rock from the Atacama Desert

Bacteria Colony? July 29, 2011

Scientists are studying rocks in Chile to learn about possible life on Mars

Looking for Life July 27, 2011

Chile's Atacama Desert is an analog for studying conditions on Mars

Mars on Earth July 26, 2011

The Opportunity rover crosses the Martian plains toward Endeavour crater

Crater Crawling April 16, 2011

Image of water distribution in northern hemisphere of Mars

Watery Mars April 14, 2011

Ground and orbital views of Opportunity rover at Santa Maria crater

Looking In February 8, 2011

Opportunity rover view of Santa Maria crater

Crater Climbing December 30, 2010

A thick dust storm blows across Mars in this image from Mars orbit.

Dusty Skies July 12, 2010

The next Mars rover, Curiosity, zaps a Martian rock with a small laser in this a

War of the Worlds? May 19, 2010

Martian 'Canali' March 14, 2010

Bright Encounter January 27, 2010