August 18, 2009

The Mars Hoax Returns

Every August since 2003, the emails start coming... Mars is going to look at big as the moon!

What's going on is this. Back in 2003 (that's 2003 with a 3, folks), Mars had an especially favorable opposition, coming close enough to Earth to appear 25 arcseconds wide. That's still pretty tiny even in a telescope — smaller, for instance, than Jupiter always appears.

Back then, someone somewhere pointed out that at a magnification of 75× in a telescope, Mars would appear as big in the eyepiece (½° wide) as the Moon does unmagnified. True enough. But two things happened, as often do with chain letters. First, it got rewritten bit by bit to improve the story as people passed it around, so that the "75×" was downplayed or, in some versions, left out. Second, the chain letter kept going and going long after August 2003 receded into the mists of history.

Don't forward that mail!

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