Mars won’t be as big as the Moon! Get over it!

Bad Astronomy
The entire universe in blog form
July 27 2007 11:55 AM

Mars won’t be as big as the Moon! Get over it!

Every year. Every fracking year.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  


The email, I hear, is going around again. The one that says that if you go outside next month and look at Mars, it'll be as big as the Moon. You know; the one I debunked here and here and here and here, every year since this dumb thing started back in 2003.

Short and sweet: Mars won't look big to the eye (the email says, not very clearly, that through a telescope mars will look as big as the Moon does to the eye) in August. It never gets that close. It won't even be particularly bright in August; it'll shine at magnitude 0.4 or so, roughly as bright as the star Aldebaren, which in fact is just a few degrees from Mars in the sky (they make a nice pair, too, since they are both ruddy in color as well).

As you can see in this image, in August Mars won't be at its closest to Earth, and in fact will be about 180 million kilometers (over 100 million miles) away.

So don't believe what you read in emails, OK? Happily, lots of other blogs, like Universe Today are trying to defuse this as well, so spread the word.

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