Observing Mars in 2005
by John Rummel

After all the hoopla surrounding the opposition of Mars in August 2003, you may be forgiven for thinking the party is over for a few years. Though Mars will not be as close or as big as it was two years ago, in at least two ways the 2005 opposition will be even better. First, opposition 2005 occurs during the cooler months of October and November (the actual date of the opposition is Nov 7 but Mars’ closest approach to earth is a week earlier, on Oct 30). This means less humidity and haze, and far fewer unpredictable thunderstorms (though to be fair, Wisconsin experiences, on average, more cloudy days in Oct-Nov than it does in Aug-Sept). Second, this opposition occurs in the constellation Aries, which means when it culminates each night (reaches its highest point above the horizon), Mars will be above 60 degrees altitude. This is far better than the 2003 opposition in August in Aquarius when it scarcely got above 30 degrees altitude for mid-northern viewers. This higher altitude alone will make Mars observing a much more rewarding and satisfying experience than it was two years ago.

When to Look
Since Mars’ closest approach is right at the end of October, the viewing is good anytime up to a month or two on either side of that date. Since I tend to do most of my serious observing on weekend nights, I prepared the table below to assist me in planning my Mars 2005 observing. The dates given are successive Fridays starting at the beginning of September and running right through the end of 2005. I have given only Mars’ angular size and magnitude, as well as rising and culmination times. Culmination times are when Mars crosses the meridian - another way for saying that it’s highest in the sky, and due south. All times are computed for Madison, but will hold true for all southern Wisconsin observing sites.

   Date  Angular Size Mag   Rises   Highest 
         (arcseconds)               Point
   9/2    14.2        -1.1  10:13pm 5:12am (CDT)
   9/9    15.0        -1.2  9:51    4:53
   9/16   15.9        -1.4  9:28    4:32
   9/23   16.8        -1.5  9:03    4:09
   9/30   17.7        -1.7  8:36    3:43
   10/7   18.6        -1.8  8:07    3:14
   10/14  19.3        -2.0  7:35    2:42
   10/21  19.9        -2.1  7:01    2:07
   10/28  20.2        -2.2  6:25    1:30
   11/4   20.1        -2.3  4:49    11:53pm (CST)
   11/11  19.6        -2.2  4:12    11:15
   11/18  18.9        -2.1  3:37    10:39
   11/25  17.9        -1.8  3:04    10:04
   12/2   16.8        -1.6  2:32    9:32
   12/9   15.6        -1.4  2:02    9:03
   12/16  14.4        -1.2  1:34    8:37
   12/23  13.4        -0.9  1:08    8:13
   12/30  12.4        -0.7  12:44   7:50 

How to Look
While some internet email myths are circulating that Mars will appear “as big as the full moon,” such talk is clearly nonsense. Mars will be bright and very conspicuous in the evening sky, but it will look like a bright orange star to the naked eye. For serious Mars observation, you need to use a telescope and eyepiece combination that will give you at least 50x magnification, and ideally, much higher. Mars frustrates many novice observers who have been spoiled with the splendor and vast detail visible with Jupiter and Saturn. Mars requires more effort and patience in observing, but will richly reward the persistent observer. Because of its small size (only 20 arcseconds at its largest), higher magnifications will rule the day, and filters can be very important in bringing out subtle details of the surface and atmosphere.

What to look for
Mars’ southern summer just began with the Martian summer solstice occuring on August 16th. Thus, throughout the period of this opposition, Mars’ southern hemisphere will be tilted toward the sun - and the Earth. Most observers will have no difficulty identifying the south polar cap. Watch to see the polar cap to diminish in size during the relatively warm days of summer.

Mars shots from the previous opposition. All shots with Nikon Coolpix 4500 and Celestron C8 telescope with Scopetronix eyepieces. South is up in all images.

Mars is much more prone to planet-wide dust storms during its southern summer, possibly because that season also corresponds to Mars’s closest approach to the sun in its eccentric orbit. This opposition occurs after the peak in sandstorm probability, but the possibility always exists that a planet-wide storm will obscure surface features, rendering Mars a bland orange disk. If dust storms do not intervene, observers can expect to see a wealth of detail on the surface, as well as meteorological activity such as clouds forming in the higher and lower surface elevations.
Sky and Telescope website has a very easy-to-use java applet that will display a labelled Mars map to correspond to your observations, to assist you in identifying and searching for surface features.


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