Mars through a Telescope: Getting the Most from the Red Planet
You don't need a large telescope to see lovely details on Mars during the 2003 opposition. A good three or four inch telescope with quality eyepieces will work just fine. Many observers prefer refractor type telescopes, which use lenses, over reflectors, which use mirrors, for planets but both will work well.
An important thing to keep in mind is that you don't want to over-magnify. Start will a low power eyepiece and then increase magnification until you reach maximum detail and clarity. Too much magnification will result in a fuzzy image with less detail.
Remember too, that the viewing can change from night to night depending on atmospheric conditions. With a calm, steady atmosphere, you will be able to use more magnification than on a night when the seeing is poor. Allow your telescope to sit outside for an hour or so before viewing. Having the telescope the same temperature as the air will improve viewing.
Plan to view Mars when it is higher in the sky. When it is low in the sky, there is more atmosphere for light to pass through and so the viewing is poorer. Higher overhead, the atmosphere tends to give more crisp views.
Another way in which you can improve the quality of your viewing is where you choose to observe from. Obviously you want as dark a skies as possible, but choosing a wide open area, or over water is also a plus. Large heat sources such as concrete buildings, and parking lots will release heat at night making the local atmosphere unstable.
As far as equipment goes, try to have a range of eyepieces so that you can get the best magnification possible. Mars is a small planet and even during opposition you will need as high a magnification as possible to see details. A good range of eyepieces would be 6mm, 8mm, 9mm, 10mm and 12mm.
A Barlow lens is used with an existing eyepiece to magnify an additional 2x. This will however cut down on light gathering ability ot the telescope. The obvious advantage is that it gives you two powers for each eyepiece.
Filters will also enhance viewing. An orange or red filter works best for bringing out detail in dark surface areas and increase contrast between light and dark areas. Green and blue filters work best for the polar caps and showing any haze or clouds in Mars' atmosphere.
Use the highest quality equipment you can afford to buy. This is one situation where more money does mean more quality. A cheap 8mm eyepiece for example, will not show you the details or quality of a good 8mm eyepiece. The coatings are better on more expensive eyepieces and this can make a big difference when observing.
As stated earlier, a good 4 inch telescope will show major features on Mars. But regardless of the size of telescope, you won't be able to see things like Olympus Mons and Vallis Marinaris from Earth, but there is still much to see. When you are observing Mars it is important to remember that you are actually looking through two atmospheres. Although Mars has a thin atmosphere, large, sometimes global dust storms can obscure surface details.
Mars has an axis tilt of 25 degrees, very close to Earth's 23.5 degrees. This means that also like Earth, Mars goes through seasons also. One very different fact about Martian seasons is that they last about twice the length of Earth's seasons because it takes Mars longer to make one trip around the Sun, nearly two years. Mars' southern hemisphere seasons are much more severe than those of the northern hemisphere because Mars is much further from the Sun during the southern winter.
The polar caps are the most obvious features on Mars. They are composed of water ice and frozen carbon dioxide (dry ice.) They caps grow during the winter and shrink sometimes to almost nothing during the Martian summers. Even a cheap telescope will allow you to see the polar caps. The next easy features to pick out are the dark areas of Syrtis Major and Meridiani Sinus.
Before you go out and view Mars, study the features map and familiarize yourself with the main features. If you want to take your map out with you, use a flashlight with red cellophane taped over the end so that your night vision will not be reduced. Also, since the Martian day is about 40 minutes longer than a day on Earth, if you observe Mars at the same time each day, you will be able to see the features rotate in and out of view.
If a large dust storm does develop, it could obscure many features but the storms themselves are great to look at. They may last for days or longer. Individual features change some themselves as seasonal winds cover and uncover darker features with lighter dust. It was this process of changing features which started the idea that there were canals and intelligent life on Mars. It was once thought that these changing dark features were seasonal plant growth. Studying Martian storms and changing surface features is a valuable amateur activity.
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Kathy Miles, Author, and Chuck Peters, Systems Administrator
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