No, no, no…a thousand times NO: Mars will not become a “second Moon” in the sky on August 27. It won’t this year, it didn’t last year, and it didn’t in the past dozen years since this silly yet strangely perennial cyber-legend (yes I just used the prefix “cyber”) first started circulating on teh interwebz. I don’t know why it keeps rising from the e-dead every year, some years more omnipresently than others, but the bottom line is it simply won’t happen. Not this time, not ever… the Solar System just doesn’t work that way. (And good thing too!)
“But wait,” you say, “couldn’t it happen? Maybe? One day? A what-if scenario?” Again, no. Mars is happily orbiting the Sun, just like Earth and all of the other stuff in the Solar System is according to Newton and Kepler’s lovely laws of gravitation and planetary motion, and it’s not going to come suddenly drifting our way for a visit just for fun. And I’m no physicist but I’d guess that any sort of hypothetical collision event powerful enough to rock a planet from its orbit would more likely shatter Mars apart entirely into a mess of molten rubble, sending chunks our way to create a global meteor shower and forming a temporary new ring of asteroids around the Sun. (But calm down – that’s not going to happen either.)
Not only will Mars not be anywhere near Earth or the Moon as of August 27, it will actually be quite far off: 2.523 AU, or about 234.5 million miles away, and almost on the opposite side of the Sun — it won’t be visible in the night sky at all. Besides, the closest Mars ever gets to Earth is about 35 million miles, which is still much, much too far away for a planet half the size of Earth to appear as large as the Moon (which is about 1/4 the size of our planet) in the sky.
In fact during an opposition event (when Earth and Mars reach their closest points in their respective orbits, which occurs every 2.13 years) on August 27, 2003, Mars came the closest to us in over 50,000 years – and still it was 34.8 million miles away. It was a nice viewing event for amateur astronomers, sure, but still very tiny in the sky compared to the Moon.
That was also when these “double Moon” rumors appear to have started, so perhaps we can just blame bad science reporting for the whole mess.
But the real problem here isn’t necessarily the (very) wrong information, it’s that people otherwise unfamiliar with astronomy who may think this is a special event that they’ll be able to witness for themselves in the night sky end up getting disappointed… which is the opposite of what astronomy should instill in folks.
Said Phil Plait on bis Bad Astronomy blog on Slate.com in 2013:
“We have enough woe and misfortune in the world as it is. Astronomy, the beauty of the sky, and the natural awe laid out before us are instead a source of wonder and joy. I’d prefer to keep them that way.”
So tell your friends, tell your mom, tell your crazy uncle who swears the “S” in NASA stands for “secret alien bases”… two Moons: it’s not gonna happen. But that shouldn’t prevent them from enjoying the beauty of a summer’s evening sky and the one beautiful Moon we do have (it will be nearly full this August 27, too.)
Want to read more? Check out some of the articles below (by some very good science reporters!)