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What's Better Than A Total Eclipse Of The Sun? Check This

Tuesday, July 22, 2014 - 01:55 PM

Any eclipse is worth seeing. A total eclipse — where the moon completely blots out the sun, where day turns to night, where solar flares ring the moon's shadow like a crown of flame — that's the eclipse everybody wants to see, the alpha eclipse that eclipses all the other eclipses. Everybody knows this (me included), until I saw this ...

Solar eclipse or cross-eyed space alien?
NASA/JPL-Caltech

Yes, it looks like a cross-eyed space alien staring out of the darkness, so to make things clearer, let me add one more "eye," like this...

A set of three images showing the larger of Mars' two moons, Phobos, passed directly in front of the sun as seen by NASA's Mars rover Curiosity.
NASA/JPL-Caltech

What are we looking at? On Aug. 20, 2013, NASA's robot Curiosity was sitting on a Martian plain and one of its cameras looked up at the sky and saw the little moon Phobos passing across the face of the sun. Curiosity's camera snapped a picture every three seconds. So what you see here is a sequence. The moon appears on the right side of the sun, moves center, exits left, a passage that took about 37 seconds. Had you been on Mars that day, this (NASA animated its photos) is what you would have seen ...

Obviously, this is not a total eclipse. Phobos, it turns out, is too small to cover the sun. It is, amazingly, only 14 miles wide. Our moon, by comparison, is 2,160 miles across.

So how does this itty bitty moon manage to loom so large against the sun, and how come it's so rock-like, so bumpy around the edges — so utterly gorgeous to watch?

The answer is, Phobos orbits very close to Mars' surface. It's only 3,700 miles up. Our moon, by contrast, is (on average) 239,000 miles away. So, Phobos is sailing very, very near, which is why Curiosity can see it in such detail and why it blots out so much of the sun.

Which Would I Rather See?

If you asked me to choose between a total solar eclipse of our moon, and a chance to catch Phobos voguing in sharp outline while I watch from a Martian plain, I'm going for the Martian option: the Little Guy in Partial Eclipse. Not only is it thrillingly beautiful, it is also, I should mention, a tragedy in motion.

Our moon, the Earth's moon, has been gradually drifting away from us. When the Earth was younger, our moon was 10 times closer than it is now. Phobos, on the other hand, isn't moving out, it's moving in — closer and closer and closer to Mars. What's more, it's slowing down.

These days it circles Mars every eight hours. But in the next 10 to 15 million years or so,Mark Lemmon of Texas A&M University told Space.com, Phobos will slow its speed so significantly that, at some point, it will "get so close that tidal forces from Mars will very likely break it up before it does start grazing the atmosphere and come down."

Oh, No ...

What happens then? When a moon disintegrates, it breaks into hundreds of millions of pieces; those pieces splay, then gather, and (at least for a while) they become a ring — like the rings we see around Saturn. When Phobos goes, "Mars may briefly have a ring system," says Lemmon.

'Goodbye,' The Little Moon Is Saying

Which is why, when you see Phobos in partial eclipse on Mars, you are watching a diva making what will one day be its final appearance in our solar system.

So consider what we've got here: a death spiral, a light show, a dying beauty backlit by the sun, What's more fantastic than that? Yes, total eclipses are still nice, still worth traveling to see, but now that I know what Mars gets to see, I'm switching sides. When it comes to eclipses, Partial is the new Total.

At least when I'm on Mars.


Thanks to Marc Kaufman, whose new book, Mars Up Close: Inside the Curiosity Mission, introduced me to some of the images featured here.

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Comments [4]

Scott Bennett from Edinburgh, Scotland.

All this talk of eclipses reminds me of the lately late and always great Iain Banks' fabulous novel Transition.

In this book he points out that our eclipse, the perfect total eclipse from a moon only just big enough to cover the sun must be as near unique in the universe on an inhabited world as unique has any meaning in a relativistic universe.

to have a moon, perfectly round at the perfect distance that you can see a corona, and to have a perfectly placed valley to give the diamond ring effect is the result of so many variables being just so that it must, simply must, be a tourist attraction.

if it is possible, using tech unknown, to travel here and if other races have got that tech already then the first to visit will have reported this marvel back.

This means we live in a universe of 4 possibilities.

1) We are the most advanced race in the galaxy so nobody has visited yet.

2) We aren't the most advanced but nobody has made it here yet.

3) Interstellar travel isn't possible.

4) (and this is good) They made it here, they reported back, and so, every total eclipse, all around us, hidden from sight by their astounding tech, stand tourists. Tourist representing all the peoples and all the forms of intelligence the universe can muster. They aren't here to conquer, kill or enslave, they're here to stand quietly next to us looking up in the same quiet wonder and awe as us at the greatest show in the universe.

Aug. 11 2014 04:17 PM
Amy from Illinois

Amazing that the cameras caught such a perfect shot of the eclipse! Wonderful to see.

Aug. 02 2014 06:55 PM
Neil

The answer is in the article. Not for 10 to 15 million years.

Jul. 24 2014 12:02 PM
Joe from Wimauma, FL

It would be fascinating to record the ring formation and its collapse. Do you think it will occur in the near future?

Jul. 24 2014 06:21 AM

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