Another Martian Invasion is Underway!
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Suspended over the eastern horizon later this evening is a bright pinkish light. It hovers there, menacingly, rising slowly in the sky as night progresses. Look out! Another Martian invasion in underway!
Mars wins the lead role in Amazing Sky Objects of the Month for August. This is not our typical biennial appearance of our nearest outside neighbor, oh no. This is its closest approach in about 50,000 years, farther back than most of us can remember.
So why so close this year? It has to do with a rare position of orbits, ours and Mars.
Mars doesn’t travel in a perfectly circular orbit; actually, no planet does. Its orbit, like ours, is elliptical, like a slightly stretched out circle. As a result, sometimes it is closer to the sun, sometimes farther. It is nearly at its closet approach to the sun now.
Add to that another important event: Mars is also near opposition. That is, it is almost on the exact opposite side of the Earth as the sun. Opposition is the time we get as close as we can to an outside planet.
Follow the logic here. If Mars is as close to the sun as it gets, and if we are then between the sun and Mars, it follows that we are now about as close to Mars as we can ever get.
During a distant opposition, when we are between the sun and Mars but Mars is not at its close approach to the sun, it can be over 60 millions miles away. But in this alignment it creeps up to a stone’s throw 35 million miles! Translation: big and bright!
It is this closeness that gets astronomers and planet lovers all giddy this month. Yes, even at this proximity Mars is still a small planet. We can’t get around that. Even as big as it seems this month, it is only about the size of a quarter held up more than 2 football fields away. But this is the best time in our lifetime to get a close-up glimpse from the comfort of our backyard. So take advantage of it!
The downside for many people is that one needs a telescope to really enjoy it. Using your own scope or one wrestled from a friend or local astronomy club, there are several things to look for in a backyard sighting.
One can see Mars' polar ice caps standing out white against the rest of the planet. They are made of combinations of water ice and frozen carbon dioxide, and they shrink and grow with the seasons.
There are geographic areas all over the Red Planet that reflect different amounts of sunlight and give the surface dark and light detail. Alas, if you are looking for canals you won’t find them. They are the thing of myth and legend.
It is probably important to start observing even before Mars gets to its closest approach on the 27th. This is because of the dreaded Martian dust storms that kick up as the weather changes there at this time of its year. These storms can literally cover the entire planet, erasing the detail that makes Mars watching so interesting.
You might consider calling a local astronomy club to see if they are hosting any star parties this month. They are usually more than willing to let you and your family sit in on one. And check out the websites of Astronomy or Sky & Telescope magazine to use all their resources --- maps, charts, histories, and useful viewing tips --- to fully enjoy this close encounter of a Martian kind.
Mark Ritter teaches astronomy at Temecula Valley High School and can be reached at mritter@firstlightastro.com.
Posted by Administrator at 2003.08. 2 01:18 PM | Comments (0)
