Marvelous Mars
November 2005 :
Note: This article may contain outdated information
This article was published in the November 2005 issue of The Skyscraper and likely contains some information that was pertinent only for that month. It is being provided here for historical reference only.
When I'm able to show a young child a great view of Mars through our 8 1/4 -inch Alvan Clark refractor telescope, I often wonder if that young person may be the first earthly explorer to set foot upon its rusty soil. They may get to visit the crash or landing sites of our earlier unmanned explorations. They'll get to see firsthand the magnificent "geological" structures explored by the rovers. This adventurer will be able to step up to a rock outcropping and pick away at the formation hoping to discover evidence of past life. (Much like I imagined doing as I watched the fantastic images transmitted to Earth from the Mars rovers.)
For this article I am not going to recount the history of Mars observations or spacecraft explorations other than to say the initial accounts of possible "canals' on Mars at the end of the 19th century captured our imagination and most assuredly hastened our spacecraft exploration of this desolate world. If you would like some historical background, visit Skyscrapers web site at http://www.theskyscrapers.org/ and look for an article entitled "Mars History Highlights."
First, let's examine how this close approach of Mars in 2005 is different than it was in 2003. Two years ago, on August 27, 2003, Mars came closer to the Earth than it had in 60,000 years, at a distance of 34,646,418 miles. Viewing was pretty good. Most folks who looked through our telescopes at Seagrave Observatory not only saw the South Polar Cap (SPC), but also got views of many of Mars' dark surface features. Though we had many nights of fairly decent observing conditions, Mars was always very low in the sky, never quite rising above the atmospheric turbulence. 2005 will be different.
Though Mars will be almost 10,000,000 miles further away from the Earth (43,137,588 miles on the night of October 29-30 in 2005), the god of war will be much higher in the sky. In fact, when Mars is on your meridian (due south of your location) he will be about 60 degrees off the southern horizon. This favorable placement may make up for Mars' much further distance when it comes to gleaning planetary surface details. The image will definitely be smaller than in 2003, but the hopefully steady atmosphere will provide a higher quality image.
As soon as you read this column, you should begin looking for Mars. At 9:00 pm on the night of close encounter (October 29/30), Mars will be the bright orange/red/rust colored "star" 30 degrees above the eastern horizon in the constellation Aries, very near Taurus and the Pleiades star cluster. Mars won't be this close or this bright for another 13 years, so you should make every effort to view this desolate world before winter descends upon us.
Even small backyard telescopes will still reveal detail only fleetingly glimpsed before in larger aperture scopes under the best of best conditions. So if you have your own telescope, try observing and getting your own impression of what can be seen before you read the remainder of this column, or before you reference detailed maps. (The September issue of Sky and Telescope magazine and the November issue of Astronomy magazine each contain a fine map to aid you in identifying Martian surface features.) Using the maps first may prejudice you into thinking you are seeing something when you aren't! Observe first, make a few crude drawings, and then go to the maps to see if you were right. I've provided a few web sites at the end of this column where you can find more information.
You don't have your own telescope? Then plan on visiting Seagrave Observatory some clear Saturday night through December at least (or until snow drifts close our parking lot!!) You can still prepare for your visit by reading the remainder of this column. Get ready for another close encounter of the planetary kind!
Normally Mars is quite a challenge to observe from Earth. Its usually small appearance through a telescope makes it difficult to discern much surface detail, other than a polar cap or a large feature like Syrtis Major or the Hellas Basin. However, this close encounter will provide views of surface detail that many of us have only glimpsed during past, less favorable encounters. In fact, despite Mars' greater distance from us, the detail seen may even rival that observed in 2003.
What we will still need is some good observing conditions. The telescopic image must be steady under medium to high magnification, else the details will blur into indistinct and formless features. Your telescope and mounting must also be sturdy. Any motion of the scope under the magnifications necessary for observing Mars will be quickly transmitted to the image. A clock drive to counter the Earth's rotation is also recommended to keep Mars' image centered in the eyepiece at all times. Seagrave Observatory's telescopes meet these mechanical criteria.
Unless a global dust storm completely covers the planet by the time this article is printed, the first feature that will catch your eye will be the South Polar Cap(SPC). It is conveniently tilted towards the Earth, giving us a great view. Watch it carefully over the coming weeks. When spring began in Mars' southern hemisphere on May 5, the SPC began to melt. Summer solstice occurred on September 29, providing more sunlight to shrink the cap. You should soon notice the SPC continuing to shrink as time progresses. Ideal observing conditions may allow you to see some irregularities. During past oppositions dark rifts have isolated portions of the cap as detached segments. The SPC may even disappear entirely.
The rest of the planet will appear as a rust-colored beach ball. Several dark features can also be seen. These are the underlying rock exposed by the shifting sands during intense dust storms. On the night of close encounter, a prominent and most distinctive dark feature called Syrtis Major will be facing the Earth. This remnant of a shield volcano straddles the Martian equator and extends northward 930 miles towards the SPC. Its east/west breadth is about 620 miles.
I find it most difficult to describe this region, for the shifting sands during the changing seasons often alter its appearance. Just at the end of the 1800's Syrtis Major was known as the "Hourglass Sea" due to its shape. It can appear like a narrow tornado winding down and about to "rope out," or it can look like a broad F5 monster tornado. Some see it as a shark's fin! More often than not, to me it looks like an irregular image of the Indian sub-continent on Earth. Let me know how you view this planetary Rorschach ink blot test.
Be aware that the Martian day is 24 hours and 37 minutes long, while our day is 24 hours long. The extra 37 minutes has an effect on your observation of surface features. If you see a dark feature on Mars' central meridian (an imaginary line that bisects the planet) one evening at 12:00 midnight, the next evening it won't return to the central meridian until 12:37 am. On the following night it would arrive 37 minutes later. Therefore, to ideally observe the same piece of Martian real estate on the central meridian each successive night, you must wait an additional 37 minutes.
You should begin watching for dust storms immediately. As of this writing in early October, none have yet to be reported. If you can identify specific surface features, dust storms often begin in the Hellas Basin, a deep meteor impact basin visible just between Syrtis Major and the SPC. The global dust storm that prevented our observations of Mars in 2001 started here.
Dust storms begin as small yellow clouds that grow and grow and can eventually blanket the entire planet. Whitish water vapor clouds can also be detected, as well as bright spots of frost. These features are all possible to see, though you will probably have great difficulty observing anything more than the SPC and some of the dark surface features with a three-inch or smaller telescope.
In conclusion, be patient when observing Mars. The disk of the planet, though larger in appearance from most years, is still relatively small. Features will be easy to detect during this close encounter. Wait for steady seeing conditions. Don't try observing Mars if the stars are twinkling. Take your time in observing this fascinating planetary neighbor and your efforts will be well rewarded. If you check out the Mars JPL web site you can see where the rovers are exploring and determine if they are on the hemisphere facing the Earth. I'd imagine myself strolling right beside either of them to experience the wonders of Mars.
This column has presented only a simple introduction to Mars observing. You will not duplicate the observations of some of the late 19th century astronomers, nor will your view be anything like the electronic images recorded by astronomers you might see on television or when you surf the net. You will, however, be able to take a knowledgeable glimpse of an alien world that inspired generations of astronomers and science fiction writers alike to ponder the existence of Martian life-forms. So drag out those telescopes and expose them to the light of the universe. One day your children or your grandchildren may set foot upon this exciting landscape.
Remember, Seagrave Observatory is open free of charge to the public every clear Saturday night. Once Mars clears the treetops to our east, our weekly focus will be on the red planet. I'd advise you to visit soon before winter settles in. Once again the The Old Farmer's Almanac has predicted a colder than average winter with above average precipitation for us. So come and take advantage of the viewing opportunities we can provide with our four major telescopes. Check our web site at http:/www.theskyscrapers.org for further information, and always keep your eyes to the skies.
