|
Don Shedrick |
May, 2003 |
May DAS Focus
COMPUTERS IN ASTRONOMY by Don Shedrick
With each passing night, Mars is getting closer to Earth. At 5:51 a.m. EDT on Aug. 27, 2003, Mars will be within 34,646,418 miles (55,758,006 kilometers) of Earth. This will be the closest that Mars has come to our planet in nearly 60,000 years. At this time, Mars will be at opposition, the moment when the Sun, Earth and Mars will form a straight line and the red planet is closet to Earth.
Mars comes to opposition about every 26 months, but because of the elliptical orbits of Earth and Mars, not all oppositions are result in the same Earth/Mars distance. The 2003 opposition will be superior to all the others because Mars will be very near to its closest point to the Sun, called perihelion, when it arrives at opposition.
Such perihelic oppositions of Mars are in themselves, rather infrequent, occurring about every 15 to 17 years. The most recent one took place in September 1988, when Mars passed to within 36.5 million miles (58.7 million kilometers) of Earth.
There are several web sites and programs that will help you get the most out of your observations of Mars during this historic opposition.
MarsNews.com has partnered with the Open Directory Project to offer Internet users the Mars Open Directory, a collection of the best Mars websites. It can be found at:
http://www.marsnews.com/directory/
Space.com has a wealth of information at their Where is Mars Now? Web site:
http://www.space.com/spacewatch/where_is_mars.html
It has locator charts and tables of viewing circumstances for every two weeks.
At the Roving Mars Atlas web site:
http://www.roving-mouse.com/planetary/Mars/Atlas/
Point at the globe of Mars to see large feature names. You can rotate the globe to view the other three hemispheres, and Click to view a color closeup. Point at closeup to see the names of small features like craters. Click to zoom in to an even higher resolution map at USGS.
It helps to know what to look for in observing Mars, and in particular what side of the planet is facing earth at your observing time and what features would be visible. Since the Martian day is only slightly more than Earth’s, it takes over a month for the side visible from earth to complete one rotation if viewed at the same time each night. There are several web sites or programs that provide information on what side of Mars is facing us.
Mars Previewer II is a very impressive program for Mars watchers written by Leandro Rios, an amateur astronomer in Argentina. This displays the central meridian, phase, magnitude, and angular size of the red planet for any date and time. It is available as freeware on the Sky and Telescope web site:
http://skyandtelescope.com/resources/software/article_328_1.asp
Also at the Sky and Telescope web site is the Mars Profiler. This is a Java Script program that displays a map of the side of Mars that is visible for the time entered, as well as other information such as visual magnitude, distance from Earth, angular diameter, number of days to opposition, etc. It can be found at:
http://skyandtelescope.com/observing/objects/planets/article_929_3.asp#
Mars Today, created by Howard Houben of the Mars Global Circulation Model Group, is a poster produced daily by the Center for Mars Exploration (CMEX) at NASA's Ames Research Center. The poster at:
http://humbabe.arc.nasa.gov/MarsToday.html
depicts current conditions on Mars and diagrams the current positions of Mars and Earth in their orbits around the Sun. There is also animation of the orbits of Earth and Mars through 2000 and 2001 showing their relative positions and tilts of their rotation axes that are responsible for the seasons.
The images of Mars from the above software programs will take on more meaning if you use a more detailed map to identify the Martian features. The Association of Lunar and Planetary Observers has a detailed Map of Mars on line at:
http://www.lpl.arizona.edu/~rhill/alpo/marstuff/Mars2000.jpg
with all major features and degrees of longitude labeled.
Much more Mars info, including news, Mars missions, maps and atlas, landing sites info, and many images are provided at The Center for Mars Exploration site at:
This summer when you are hot and sweaty, get a refreshing glimpse of the latest chilly Martian Weather Observations from the Mars Global Surveyor Radio Science Team. They are posted regularly on the site:
http://nova.stanford.edu/projects/mgs/dmwr.html
Have a great summer!
