Mars 2003!

Thursday, June 12 2003 @ 06:51 am EDT

Contributed by: Admin

The Red Planet is getting closer day by day... and on August 27, 2003, Mars will be a mere 34,646,418 miles away from Earth - the closest it has been in over 73,000 years. In preparation for the best Mars viewing ever, now would be a great time to reacquaint yourself with our close neighbor.

Stargazers have long been fascinated with Mars because of its reddish color and quick movement through the stars. A Martian day is about 25 hours long, and the passage of its seasons takes 23 Earth months (this is the time it takes Mars to complete its orbit of the Sun). With its elliptical orbit, the distance between Mars and Earth varies at different oppositions. The angular diameter (the size of the disk as it appears from Earth) ranges from as small as 4" (arc seconds) to about 25". The closer we are to Mars, the larger it appears.

Hubble Photo

Keep in mind that in late August when Mars is closest (diameter about 25 arcsec), it will only rise about 30 degrees above the horizon at midnight ... so not good for "early evening" observing. However, this situation improves through September: at end of September, Mars will still be over 20 arc sec. in diameter,but will cross the meridian (a bit more than 30 degrees high) earlier ... about 9:30PM...

The seasonal changes on Mars are the result of great dust storms brought about by solar heating. The polar ice caps wax and wane with the seasons, and are comprised of frozen carbon dioxide over a core of frozen water. As always, there is the danger of planet-wide dust storms at this perihelion. Storm activity on Mars can easily wipe out any surface features otherwise visible.

Mars has two small moons, neither of which exceeds magnitude 11 or 12. Their orbits are elliptical because gravity has not made them round, as is the case with our own Moon. They are:

  • Phobos - (Greek for 'fear') has a diameter of 16 miles.
  • Deimos - (Greek for 'terror') has a diameter of 9 miles.

Some observers find that filters are useful for studying surface details - when they haven't been obscured by the giant dust storms. An orange filter can be helpful with increasing contrast. A blue filter may reveal the status of dust storms. A yellow or green filter is best for the morning clouds.

The chart below tracks Mars up to the closest approach in August.

Date Distance Magnitude Constellation Rise Time

May 1581.8-0.3Capricornus00:51 / 07:51
May 3170.6-0.7Capricornus00:18 / 07:18
June 1461.9-1.0Aquarius23:45 / 06:45
June 3052.6-1.4Aquarius23:02 / 06:02
July 1445.8-1.8Aquarius22:21 / 05:21
July 2939.8-2.3Aquarius21:30 / 04:30
August 1236.1-2.6Aquarius20:33 / 03:33
August 2734.65-2.88Aquarius19:26 / 02:26
  1. Distance is specified in millions of miles.
  2. Magnitude is the apparent brightness.
  3. Rise times are specified in local time and universal time (local / UT).

You can try to gauge how bright Mars will appear in the coming months by comparing its magnitude on a specific date against a star of similar brightness.For example: on February 5, Mars will be equal in brightness to the star Fomalhaut in Piscis Austrinus. By March 3 it will be similar both in brightnessand color to the star Aldebaran, in Taurus. By May 1 Mars will be glowing as brightly as Vega, in Lyra. Thereafter, Mars will increasing in brilliance at adramatic rate, doubling in brightness every 31 days. By the end of June, it will be equal Sirius in Canis Major (the brightest of all stars) and on July 16, Mars will even surpass Jupiter, moving into second place in brightness among the naked-eye planets, a ranking that Mars will be maintain into early October 2003.Only Venus gets brighter.

Story submitted originally by AOAS member Devon Oxford

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