Christmas 2007 is upon us and we have not one but two bright Christmas stars shining over us, one in the early morning sky and the other visible all night. I’d like to tell you that one is green and the other red for this festive holiday season, but I can only go halfway. The morning star is actually a dazzling bright white, but the other shiner rising in the evening has a definite reddish hue that you can easily see with the naked eye.
Actually, these two stars aren’t stars at all. They are the planets Venus and Mars, the Earth’s next-door neighbors in our solar system. Venus is without a doubt the brightest starlike object in the morning sky and has been with us in the predawn hours through the last part of summer and all of autumn. Just look in the southeastern sky before morning twilight and even during the first part of twilight, and I guarantee it will burst out at you. As bright as Venus is to the naked eye, it’s not all that impressive through even the biggest telescopes, because it’s completely shrouded in poisonous but highly reflective clouds that bounce all kinds of the sun’s reflective light our way.
The Christmas “star” in the evening is the planet Mars, named after the Roman god of war. While that doesn’t actually fit in with the yuletide greeting of peace on Earth, it has a definite festive reddish glow to it as it climbs high in the eastern evening sky. Mars is in what astronomers call opposition this month, when the Earth finds itself in a line between the sun and our red neighbor.
Because of the different orbital speeds and periods of the Earth and Mars around the sun, this takes place every 251/2 months. Because of the astronomical geometry of opposition, Mars rises at sunset and sets at sunrise just like a full moon, and the two planets are at their minimum distance from each other in that two-year cycle. However, since the orbits of Mars and the Sun are not exactly circular but more elliptical or oval shaped, not all minimum opposition distances are the same. Some are closer than others.
In August 2003, Mars was only about 34 million miles away and was the closest it’s been to us in more than 60,000 years. You may remember all of the hoopla when that happened. Mars isn’t quite as close this time around, a little over 54 million miles away, but it’s still worth a look through your telescope, perhaps the one you may be getting for Christmas.
I have to be honest with you though. Mars is not an easy telescope target, even through larger telescopes. Even though it shines brightly in the eastern sky, Mars has only half the diameter of Earth at 4,000 miles, and even at the closest it’s been to us in two years, it’s still more than 54 million miles away. The good news is that Mars takes a high arc in the sky during the course of the night, and the higher it gets in the sky the less of Earth’s blurring atmosphere you have to visually dig through to see it. It’s best to wait until after 9 p.m. to get a clearer view through your telescope. Around midnight is the best time, when Mars is at its zenith high in the southern sky, but that may get in the way of your long winter’s nap.
Think of viewing Mars through a telescope as a challenge to see as much as you can see. You need patience and persistence. Viewing conditions can vary from night to night. Not only do you need clear skies but you also need a fairly still, nonturbulent atmosphere between you and Mars. Strong winds aloft can certainly murk up the view. If you don’t see much detail on Mars on one night, try other nights.
You also need to look at Mars through the eyepiece in your scope for extended periods of time. Quick glances usually won’t do the job. Look through your scope for at least five to 10 minutes at a time to let your eye get used to the light levels in your field of view. Of course, you’ll have to push your telescope along every few minutes to keep Mars in view, unless you’re lucky enough to have a clock drive on your scope.
Through most smaller scopes about all you are likely to see when you look at Mars is a small orange-reddish disk, although you might see part of the planet’s northern polar cap. If your telescope gives you an inverted view of the object you’re looking at, like most scopes do, you may see a whitish tinge on the lower right edge of the disk. If your telescope gives you a right side up image, the polar cap will be on the upper left edge of Mars’s disk.
If conditions are just right, you may also see some dark splotches on Mars that are a part of its extensive valley system. You may also notice that the arrangement of the surface features of Mars change as our red planetary neighbor rotates on its axis every 24 hours and 40 minutes, a little slower than our Earth. There’s a very good piece of software that you can download from Sky and Telescope magazine that shows you what Martian surface features are facing Western Washington at any given time. Just Google “Mars Profiler” and you should find it.
For your added Mars holiday entertainment, the full moon and Mars will be practically touching tonight. Mars will be less than one degree to the right of the moon.
Check Mike Lynch’s Web site, www.lynchandthestars.com.
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