Seeing Mars With A Telescope
Posted by Brian Ventrudo
The planet Mars approaches opposition on March 3, so the next many weeks are the best time to observe the planet until 2014. Many new stargazers are disappointed by their view of Mars in a small telescope. But with a little practice and know-how, you can see a remarkable amount of detail with a modest instrument. Here’s what to look for…
While Mars looks lovely in the sky right now, to see any detail on the surface of the planet, you’ll need a telescope. Binoculars will enhance the color of the planet, but won’t show the disk of this small world.
Temper your expectations when you look at Mars through a telescope. No matter how big your scope, Mars won’t look anything like images you see the magazines, or in the remarkable image above taken by Damian Peach. In a small telescope, Mars looks tiny and gives up little detail at a glance. Look at this picture from 10 feet away to get an idea of what you might see in a small telescope:
With a little patience, the right tools, and some steady sky, you’ll see detail even in a 3″ or 4″ scope. And there’s a lot to see, including…
* Red Color. Actually, it’s more ochre, or butterscotch. But the striking color of Mars is the first thing you notice. It’s a result of iron oxides in the layer of fine dust that covers the planet.
* Polar Caps. Like Earth, Mars has white polar caps. They’re made of frozen water and carbon dioxide, and they grow and shrink with the Martian seasons. Mars is inclined by 25 degrees to its orbital plane, much like the 23.5 degree inclination of the Earth, so its seasons are similar
* Dark Regions. Early telescopic astronomers thought these dark regions were green vegetation that waxed and waned with the seasons. They regions are brown, not green– the perception of the color green was an optical illusion. These dark surface markings are crater fields, and they do change their appearance slightly over time as Martian winds slowly cover and uncover these regions with fine ochre dust. The most obvious regions are the triangular Syrtis Major, Mare Erythraeum, Solis Lacus, and Mare Sirenum. This tool from Sky and Telescope magazine shows you the view of the surface of Mars at any particular time as seen from Earth…
* Clouds. At high magnification, and with good seeing, you can sometimes see clouds or fog banks on the surface of Mars, or along the limb of the planet. White clouds are visible mostly near the equator or mid-temperate regions.
Here are some tips to help you see the maximum amount of detail on Mars with a telescope…
* Acclimatize Your Telescope. Bring your scope outside at least 30-60 minutes before you plan to observe. By cooling it down to the ambient temperature, you’ll prevent air currents inside your scope from degrading the image of the planet.
* Pick a Night With Steady Air. While Mars is closest on March 3rd, you’ll have at least a month on either side of this opposition to get a good view. So pick a night when the stars aren’t twinkling too much. Vigorously twinkling stars mean poor seeing, even if the sky is clear. Sometimes, nights with a little haze have steadier air than crystal-clear nights.
* Use High Magnification. Forget about your wide-field, low-power eyepieces. Start a magnification of 80-100x. Then work your way higher until the image becomes too blurry or dim. If you have steady sky, you might get to use a magnification of 50-60 times the diameter of your telescope’s objective (in inches), at best.
* Wait For Good Seeing. As you watch the disk of Mars, you’ll see it shimmer and dance as pockets of warm and cold air move through the column of atmosphere above you. Keep watching and waiting for brief moments when you the air is steadiest. You’ll suddenly see sharp details snap into view for a few moments.
* Try Color Filters
To get better contrast, use a set of colored filters if you have them. Here are some suggested filters for your Mars observing sessions:
-Yellow (#12, #15) may brighten desert regions and darken bluish and brownish features.
-Orange (#21, #23A) further increases contrast between light and dark features, penetrates hazes and most clouds, and limited detection of dust clouds.
-Red (#25, #29) gives maximum contrast of surface features, enhances fine surface details, dust clouds boundaries, and polar cap boundaries.
-Green (#57) darkens red and blue features, enhances frost patches, surface fogs, and polar projections.
-Blue-Green (#64) helps detect ice-fogs and polar hazes.
-Blue (#80A, #38, #38A) and deep blue (#46, #47) shows atmospheric clouds, discrete white clouds, and limb hazes, equatorial cloud bands, polar cloud hoods, and darkens reddish features.
If you don’t have Wratten filters, try colored cellophane, especially red or orange.
* Make a Sketch. To train your eye and your brain to see fine detail, try making a simple sketch of what you see. Every time a new detail pops out, add it to your sketch. Over 30 minutes, you will have a full record of what you have seen during the moments of optimal seeing.
* Observe Frequently. Because Mars rotates every 24 hours and 37 minutes, you’ll see almost the same face of the planet at the same time each night. If you look at the planet every 24 hours, it appears to rotate backwards a little. So extend your observing sessions over several hours on one night, or observe at the same time over the course of the next month to see both sides of the planet.