A solar eclipse… FROM MARS!

By Phil Plait | September 15, 2012 12:34 pm

OK, this is simply too cool.

The Mars Curiosity rover has already returned thousands of images taken of the Red Planet’s landscape. But on September 13, 2012, it was commanded not to look around, but to look up, at the Sun. Why? Because Mars’s tiny moon Phobos passed directly in front of the Sun, partially eclipsing it!

Sweeeeet. I blew the original image up by a factor of two for clarity.

Technically, this is called a transit – when a much smaller body passes in front of a larger one. Usually, there’s some science that can come from this; the timing of the transit gives a better orbit for the moon (since the rover’s location on the surface is precisely known), and so on. In this case, though, we study Phobos with other orbiting spacecraft, so I’d think its orbit and position are extremely well determined.

It may very well be that this shot was taken just because it’s cool. I actually kinda hope so.

It’s not the first time a Phobos transit has been seen; in fact it’s been done several times. Here’s a video of one seen by the rover Opportunity in November 2010:

Wikipedia has more info. I’ll note that as of right now, the image above is the only one I’ve seen listed on the Curiosity raw images page (at decent resolution, that is; there are lots of tiny thumbnails, and bigger, cleaner versions should show up soon). The image was taken by the MASTCAM, which has a filter on it so it can observe the Sun. It does that for various reasons, including being able to observe how much the Martian atmosphere is absorbing sunlight.

Phobos orbits Mars pretty close in, just about 6000 km (3600 miles) above the surface of Mars – compare that to the 400,000 km distance from the Earth to the Moon! Phobos is so close that it transits the Sun pretty much every day for some location on Mars, making this something of a less-than-rare event. It’ll only be a year before it happens again at Curiosity’s location.

Still. It’s an eclipse, seen from Mars, taken by a nuclear powered one-ton mobile chem lab that we put there. I think that qualifies as pretty damn cool.

Image credit: NASA/JPL-Caltech/Malin Space Science Systems. Tip o’ the heat shield to… MarsCuriosity on Twitter!

Related Posts:

Curiosity’s self-portrait
Curiosity looks Sharp
Curiosity rolls!
Now you will feel the firepower of a fully armed and operational Mars rover
Gallery – Curiosity’s triumphant first week on Mars


Comments (30)

  1. carbonUnit

    Coolness indeed!! Where is the line between a transit and an annular eclipse? Or did Phobos even get totally within the outline of the Sun??

    Wow, this is the first time I’ve seen the BA Blog be The Top Story in Google News: Science. :)

  2. Geri Monsen

    “…by a nuclear powered one-ton mobile chem lab…”

    With a frick’n laser!

  3. MikeB

    Has a Deimos transit been photographed?

  4. Chris

    If you were on Mars would it be OK to stare at an eclipse?

  5. I’m taking a model there for my next eclipse shoot. When’s the next full solar eclipse??


  6. Chip

    A few years ago I recall seeing a black & white image of the shadow of Phobos on the surface of Mars as seen from one of the Mars orbiters. Seeing the transit from the surface is especially cool!

    I wonder if you were standing in the center of that surface shadow, would you see Phobos transit squarely through the middle of the Sun?

  7. RAF

    Just friggin amazing…

    2017 is just around the corner….then we can see a TOTAL eclipse from most of the continental US.

    Oh boy, oh boy, oh boy…I can hardly wait. 😀

  8. carbonUnit

    #5 Dario – the next total eclipse will run from coast to coast across the US on Aug. 21, 2017.

  9. Kit Watson

    According to Alan Boyle over at Cosmic Log (http://cosmiclog.nbcnews.com/_news/2012/09/15/13884492-martian-moon-bites-into-the-sun), it seems there are a sequence of images that will be coming down later and combined into an animation video, and that there will be an opportunity for the same thing to happen with Deimos.

  10. worlebird

    I find it interesting that even though Phobos is MUCH smaller than our own moon, the combination of it orbiting very close to Mars (making it look larger) and the Sun being further away from Mars (making it look smaller) results in a very similar kind of eclipse to that which we see on Earth. You can tell Phobos could not cover the entire Sun (for a total eclipse), but it looks like it it pretty close. At least, the apparent sizes of Phobos and the Sun are much closer than I would have expected.

  11. Chris

    @9 carbonUnit
    A decent partial eclipse will be visible from most of the US on Oct. 23, 2014. A nice warm up for the big event.

  12. VinceRN

    Amazing. I had the scales all wrong in my head, I thought it would appear much smaller against the sun.

    Pretty damned cool indeed.

  13. ed

    “2. Geri Monsen Says:
    September 15th, 2012 at 1:31 pm

    “…by a nuclear powered one-ton mobile chem lab…”

    With a frick’n laser!”

    OK, THAT was funny! ! !

  14. Atheist Panda

    @8 RAF
    Ditto with the amazing stuff. Looking forward to Mar 20 2015, for the next total eclipse visible here in the UK…..


  15. Ole

    Is it bad that the first thing I thought when I saw that image – before reading anything – was that someone had hacked up Apple’s logo and flipped it over…?

  16. Philippe

    “Still. It’s an eclipse, seen from Mars, taken by a nuclear powered one-ton mobile chem lab that we put there. I think that qualifies as pretty damn cool.”

    **Anything** taken by a nuclear powered one-ton mobile chem lab that we put there is pretty damn cool.

  17. amphiox

    re; a Deimos transit

    Since Deimos is smaller and further away than Phobos, it’s transit would presumably be less impressive to look at.

  18. #15 Atheist Panda:
    But we don’t see it as a total eclipse in the UK – only a partial. We don’t get another total in the UK in our lifetimes.

  19. #9 CarbonUnit:
    The next total solar eclipse occurs on 21 Aug 2017???????????????
    That’s news to me!!!!!!!!!!!!
    FYI, the next total solar eclipse occurs on 14 Nov this year, crossing Queensland, Australia, and a lot of ocean. I’ll be there, hopefully observing it!
    There are also a couple more, in not very accessible places, between that one and 2017 – which is of course the next one in the US. I also plan to see yours.

  20. #CarbonUnit:
    “Where is the line between a transit and an annular eclipse?”

    There isn’t one! What we call an annular eclipse is technically a transit of the Moon.
    Strcitly speaking, there is no such thing as an “eclipse of the Sun” or “solar eclipse”! The word “eclipse” really means one body passing through the shadow of another – so the term “eclipse of the Moon”, or “lunar eclipse” is correct, but “eclipse of the Sun” is dead wrong.
    A total solar eclipse is really an occultation of the Sun by the Moon, and an annular eclipse is a transit of the Moon. But the term was in common use for centuries, before astronomers adopted these formal definitions, so we’re stuck with it.

  21. CatMom

    Here’s a pretty good site about the 2017 eclipse:
    Lots of good info on where to see it from!


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