Wednesday, August 22, 2007
Beware of Exagerrated Mars Information!
The following excerpt is from an email I received today from a co-worker who wants to know if the details are true. Let's take a look at the unaltered original text...
Two moons on 27 August, 2007. 27th Aug the Whole World is waiting for... Planet Mars will be the brightest in the night sky starting August. It will look as large as the full moon to the naked eye. This will cultivate on Aug. 27, 2007 when Mars comes within 34.65M miles of earth. Be sure to watch the sky on Aug. 27, 12:30 am. It will look like the earth has 2 moons. The next time Mars may come this close is in 2287. Share this with your friends as NO ONE ALIVE TODAY will ever see it again.
Forgetting for a moment that the typist probably meant to use the word "culminate" rather than "cultivate", this message is, as my grandfather used to say "full of old shoes".
Mars is currently in Taurus, and is shining at magnitude +0.4 (which is brighter than all but eight of the brightest stars), but it is a mere 7.8 arc seconds wide. What the message refers to took place in August 2003 when Mars was shining at magnitude -2.9 and was 25 arc seconds wide, while moving through Capricornus.
However, the sender did get two things right, the first being that Mars, in August 2003, was as close as it has been, (and will be) in a long time, but it was nowhere near as large as the full Moon. The full Moon is roughly 2000 arc seconds wide, or 80 times the apparent size of Mars at its biggest and closest. For Mars to appear as large as the full Moon in our skies, it would be a mere 433,125 miles away (the Moon is 240,000 miles away) rather than the 34.65 million the sender gives (which was also correct).
I get messages like this from time to time because people know that astronomy is one of my hobbies, and I have gotten variations on this particular theme in the summer of 2005 as well, so I feel it is my duty to correct things as best I can from this humble vantage point. Feel free to pass this on to anyone else who could be potentially duped by this mis-information. And a tip of the hat to Jesse for sending me the message which got this ball rolling.