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No, Mars Won’t Be as Big as the Moon in the Sky on Thursday

Sorry, skywatchers: Despite what you may have heard, Mars won't look as big as the moon overhead on Thursday night.

The "Mars Hoax" has been popping up every Aug. 27 since 2003, when it was born in a widely misinterpreted email. The unknown sender of that message was trying to get people excited about an unusually close approach of Mars to Earth in late August 2003.

Why Is Mars Red? 0:42

"The encounter will culminate on Aug. 27 when Mars comes to within 34,649,589 miles of Earth and will be (next to the moon) the brightest object in the night sky," one paragraph of the email reads. "It will attain a magnitude of -2.9 and will appear 25.11 arc seconds wide. At a modest 75-power magnification, Mars will look as large as the full moon to the naked eye. Mars will be easy to spot."

Unfortunately, many people glossed over the "at a modest 75-power magnification" part and ran with the notion that the moon would have a big, red rival in the sky. This myth persists, despite repeated debunking stories at Space.com and in numerous other media outlets.

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In fact, Mars can never appear as large as the moon in the night sky. The Red Planet is about twice as wide as the moon and would therefore have to get within about 476,000 miles of Earth — twice the distance of the Earth to the moon — to be moon-sized to the naked eye.

Mars' orbit, of course, keeps the Red Planet tens of millions of miles from us at a minimum.

Related: Why NASA and Matt Damon Love 'The Martian'

So what will Mars look like in the sky tonight? In a word, ordinary. The Red Planet is about seven times farther from Earth, and about 70 times fainter in the sky, than it was in August 2003.

This is a condensed version of an article that appeared on Space.com. Read the original story here. Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+.

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