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Mars Opposition 2010!
It's here!
Updated January 28, 2010
Mars is the only planet with a surface that can be easily seen through amateur telescopes. Despite its small size, which is about half the size of Earth, Mars has higher mountains, larger rift valleys, and larger impact basins than Earth. Most of these intriguing geologic features are covered with dust, which obscures the view from amateur telescopes. What we mostly see through telescopes is darker cratered terrain in the south and lighter smooth plains in the north. The north polar cap is also easy to see right now, too!

What will Mars look like in your telescope? It depends. You may be able to see different color markings on the planet clearly, depending on such variables as the quality and cleanliness of your telescope optics, magnification and quality of your eyepieces. Weather and atmospheric conditions, both on Earth and Mars impact your view too. If you are observing Mars at low power through a small 60mm - 100mm aperture telescope, Mars will look like a small orange disk or sphere, and you may see some dark markings and the north polar cap (at least now through February 2010). Larger telescopes will reveal not only details on the planet, but also some haze on the limbs or edges of the sphere.

Here is an image showing the apparent size of the moon and Mars imaged when Mars was a little larger than it is now. Image compiled by Gary Spiers, used with permission. During closest approach in 2010, the apparent diameter of Mars will be 14 arcseconds (arc sec) or a little less than half the apparant diameter of Jupiter which is still easily visible and bright in the southwestern sky right now. Jupiter is 34 arc sec in diameter. Compare the two objects if you can. Mars is easy to see against the faint stars of the constellation Cancer a third of the way between the eastern horizon and overhead a few hours after sunset.

January 2010: The diameter of Mars this year is a little smaller than it was last opposition in December 2007. It is at opposition on January 29th, and reaches its closest approach to Earth a few days earlier. View Mars all night, from sunset to dawn by month end, but your best views will be when Mars is higher in the sky, from several hours after sunset until after midnight. The (hours from) full moon rises 7 degrees below Mars on Friday night January 29th, offering a pretty side-by-side comparison until dawn. Mars won't be this big or bright again until 2014. Remember how the moon and Mars look side-by side this month. Then, in August, when that dopey Mars Hoax email comes back to haunt us, you can tell everyone you saw Mars in January 2010 when it was closest to Earth and it was definitely not as big as the moon. :-)

February 2010: Mars is visible all night long. Do you see any changes in the North Polar Cap this month? Mars will be getting smaller as the distance between Earth and Mars grows. This is "Get out and have a look at Mars if you haven't already" month. You will be sorry if you miss it!!

March 2010: Mars shrinks in size as Earth overtakes it in the sky. 14 arc seconds diameter in January, but in March Mars shrinks in apparant diameter to only 9 arc seconds in diameter. This is the final month of really good Mars views this year.

April 2010: If you look at Mars in the southern sky during April, you will see it has a gibbous or shrinking phase. But from the 15th to the 18th Mars passes near the pretty open cluster, M44, which is also known as the Beehive cluster. Mars sets by 2:30 am eastern time now.

May 2010: You'll find Mars in Leo now, in the south-western sky, smaller than in April. It is now half the diameter it was in February. Can you see the shadow edge making Mars gibbous phased? Mars is now at summer solstice and the North polar cap should be melted away.

My own monthly NASA podcast What's Up Podcast offers up some great viewing tips each month. The January 2010 podcast is about this month's Mars Opposition, and shows you when and where to look if you want to see the side of Mars where Spirit, Opportunity and Phoenix are located.

Here's a good link for celestial highlights for the current week (and every week). This Hubble image depicts Mars in its orbit around the sun, showing the apparent relative size of the red planet at opposition for the last several oppositions. 2010's closest distance between Earth and Mars will be 62 million miles in January 2010. Look at the 1995 and 1997 images to get an idea what the apparent size of the planet will be then.

Here are some good Mars links.

Sketches and images of Mars 2001-2007

Missions to Mars

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created by Jane Houston Jones
Index last updated: January 28, 2010