“I heard Mars is going to look as big as the Moon this August! Is that true?”

Sadly, no. This whole thing started as a hoax email in August 2003 when Mars did make its closest pass to the Earth in about 60,000 years. It was a clever hoax, with some truth in it, some obfuscation, and a few completely incorrect assertions. In my opinion, it was probably originally written by a well-meaning astronomy buff.

The happy truth is that Mars makes a close pass every 20 months or so. The next one is December 2007. Because Earth and Mars do not have perfectly concentric, circular orbits around the Sun, close passes (also known as Mars Oppositions) vary in distance. All Mars Oppositions are a special treat for backyard astronomers, and many are just a tiny bit farther away from us than the modern record.

Read a hoax rebuttal here in Sky & Astronomy.

The key to this exciting hoax is a sentence that looks something like this:

“with a moderate 75x magnification

MARS WILL APPEAR AS BIG AS THE MOON TO THE NAKED EYE!!!”

It’s understandable that many people miss the understated mention of magnification. This is technically correct: the Moon is about 1/2° wide, and Mars at opposition is about 1/60th of that. Magnify Mars with a telescope about 60-75X, and yes, through the telescope it will appear about as big as the Moon does to the naked eye. Unfortunately, because the telescope also magnifies atmospheric turbulence and other imperfections, the view won’t be as clear and detailed as looking the the Moon. Nevertheless, it is a beautiful sight, especially if you know to ignore the hype.

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