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We’ve begun to field questions about Mars being as large as the Moon this summer.  Some of you may have seen the e-mails with the following claims:

• "Two moons on 27 August"
• "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 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. "

and of course "Share this with your friends as NO ONE ALIVE TODAY will ever see it again."

All we can say is that apparently some things never go out of style, and this "Mars Spectacular" message may be one of them. It’s yet another example of a widely-circulated e-mail containing information that was once true but which continues to be forwarded around year after year, long after the information it contains has become outdated.

Mars did make an extraordinarily close approach to Earth several years ago, culminating on August 27, 2003, when the red planet came within 35 million miles, 56 million kilometers, of Earth, its nearest approach to us in almost 60,000 years. At that time, Mars appeared approximately 6 times larger and 85 times brighter in the sky than it ordinarily is.

What seems to confuse most readers of the e-mail is that the third line that claims that Mars will be as large as the Moon is often reproduced with a line break, leaving many with the mistaken impression that Mars would "look as large as the full moon to the naked eye" without realizing that the statement only applied to those viewing Mars through a telescope with 75-power magnification.

Although Mars’ proximity to Earth in August 2003, which is referred to as a perihelic opposition, was a rare occurrence, the red planet comes almost as near to us every 15 to 17 years. To the unaided observer, Mars’ appearance in August 2003 wasn’t significantly larger or brighter than it is during those much more common intervals of closeness.

Mars had another close encounter with Earth in 2005, but that occurrence took place in October, and the red planet appeared about 20% smaller than it did during similar circumstances in 2003. Mars also made a close approach to Earth in December 2007, but even then it was still about 55 million miles away from us, not nearly as close as it was in 2003 or 2005. Not until 2018 will our view of Mars be similar to the one that was available in 2003, and it won’t be until the year 2287 that Mars will come closer to Earth than it did back in 2003.