STEREO eclipse

By Phil Plait | March 2, 2007 2:52 pm

Y’know, when I saw the McNaught animation from STEREO I was totally enthralled, and I figured it’ll be a while before they can top that.

Bzzzzt. It took them a day.

STEREO-B caught what astronomers call a transit — the passing of one celestial body in front of another — but in this case it’s OK to call it what it is: a solar eclipse, when the Moon passes in front of the Sun.

On Earth, the Sun and Moon are about the same size in the sky. Every person on Earth, since as long as there have been people, have seen the Sun and Moon about the same size in the sky. The only exception I can think of were the Apollo astronauts, who, as they approached the Moon, saw it as being bigger than the Sun.

But no one, ever, has seen the Moon pass in front of the Sun when the Moon was significantly smaller than the Sun. No one.

Until now.


It’s, well, it’s impossible to do it justice. This is quite simply one of the most beautiful things I have ever seen. It’s not just the video itself, it’s knowing what I’m seeing. The seething surface of the Sun, the sunspots (glowing white in this ultraviolet view), the fantastic prominence on the lower right side that you actually get a 3D feel for as the Sun slowly turns, the sparkling granules caused by convection cells at the surface. Then the Moon moving across the disk…


Watch it in high-res. It’s worth the wait.

[Note: I updated this post on October 17 2010, to include the link and embedded YouTube video.]

Update: Oops! I meant to mention that Saturday night there is a lunar eclipse (where the Earth’s shadow falls on the Moon) which favors the eastern part of the U.S. and Europe. Sky and Telescope has the info you need to see it. Interestingly, the Moon will rise in eclipse for me in California. I’ve never seen that before, so it’ll be cool– and it’ll even be clear tomorrow night!


Comments (29)

  1. John


    I can’t even believe that that’s real.

  2. Max Fagin

    Umm, Phil, won’t the lunar eclipses tomorrow be over by the time the moon rises on the west coast?

  3. Cameron

    I shall say this:
    I shall also say this:

  4. wright

    And this is just a sampling of the beauty in the great void out there. I could weep for the grandeur and wonder of the universe.

  5. WJM

    And CANADA! (Ahem.)

  6. Melusine

    I played the 20mb QT video over and over – the Sun is just sparkling! Beautiful. Ah, wouldn’t it be nice to be cruising in a spaceship seeing views like that?

    ‘Think I know what genre of movies I’ll be watching later tonight…


  7. Max..

    The total portion of the eclipse will be over at 6.57 pm EST. So yeah, no totality for the west coast of the USA.

  8. Tom

    I was in the space environment center the day after a lunar transit viewed by the Solar X-ray Imager on the GOES spacecraft. It produced essentially an annular eclipse, and it took a moment to realize what I was seeing. The view was in X-rays however, and not nearly as detailed as this. Thanks for pointing it out.

  9. Mark Martin

    Alex de Large (from A Clockwork Orange): “There was a window open with the STEREO on…”

  10. Just when I thought there was nothing “new under the Sun” I get to see something new pass across The Sun….

  11. Tom Epps

    Just amazing. Phil, you’ll have a hard time picking out your “top ten” images this year!


  12. Mr Sauss

    Hey Phil, have you seen this promotional clip from ‘Sunshine’, depicting the transit of Mercury… as seen from space?!

    Not a million miles away (figuratively speaking), but I think the real one beats Hollywood hands down.

  13. Grand Lunar

    Even better!

    Good to see STEREO racking up the points for coolness.

  14. Grand Lunar

    I think I found another cool article for you to use, Phil. You’re probably at work at it now, but I’ll hold the benifit of the doubt:

    Cool, eh?

  15. Gary Ansorge

    Gee, I wonder if Futuramas old professor could turn his Smell-O-Scope on the sun, what it would smell like??? Burnt metal???

    Yeah, that transit is SOOOOO cool!

    Gary 7

  16. Matt J

    BEST. ASTRONOMY. MOVIE. EVARRRR! It’s pretty cool, to say the least.

  17. icemith

    OOPS, posted my comments in the wrong half relating to STEREO blogs. Should have been in “STEREO ECLIPSE”. So Phil, you may delete the other one if it pleases you. Lucky I had saved the comments to send to the NASA site, hoping for a response there too. So here’s my original comment:-

    I have spent (maybe) way too much time enjoying the “Eclipse” movie. It is terrific, and given me much to think about.

    With reference to the STEREO link which leads to the ‘movie’, showing the silhouetted moon passing in front of the disc of the sun, I noticed many streaks and spots in many frames. I subsequently checked each frame and was astounded to find so many different *events* with various angles, colors and lengths. There were also many frames with multiple tracks etc. See at 17:40 and 19:20 hours. (I had downloaded the highest quality QuickTime version – about 20Mb’s worth.).

    But I was amazed to see one track right across the moon *and*, maybe the sun too. I realise that these pix would not indicate in which direction the instigator of the streaks was travelling, due to the exposure method – shots taken every ten minutes, and almost certainly very short exposures as we are shooting the actual sun, albeit in the extreme ultraviolet part of the spectrum.

    Now I also realise that as the image was made-up from four seperate images taken (almost) instantaneously. the streaks may be artifacts of that process. But I don’t think so, – well, hoping not so anyway.

    I have catalogued most of the frames with these items, their position, and other brief characteristics. It took a while to slog through the movie, and no doubt have missed some smaller spots and very short streaks. That quite a few would not be moving in a right-angle plane, relative to the Stereo Spacecraft, then their trajectory would be longer than actually shown. Also the fact that each streak is dead straight, seems to indicate they are moving at a relatively high velocity. What could be shown is only the moment of exposure, though I cannot explain instances where spots appear across the moon and further near the sun, all in a line though the exposures are taken ten to thirty minutes apart, at 08:20, 08:30 and at least 08:40 hours.

    But I can’t really identify the streaks or spots as being logically anything substantial. Has anybody any clues as to their identity?


    PS, Melusine, I’m glad you had fun with the QT movie too.

  18. Melusine

    Icemith, yeah, I watched the med-res a bunch of times first, then went back to that the highest 20 QT. Never did get around to watching DVD movies though…

    It’s time to buy those glasses, don’t you think? I lost my last pair from seeing It Came From Outer Space some time ago. They were cheapo ones anyway. Doesn’t everything look better in 3-D? It’s certainly fun. :-)

    I can’t wait for more from STEREO – no worry about cloudy skies to block the view!

  19. Phil,

    It looks like today APOD tied you with best picture. It’s nice when you beat them, but in a tie APOD always wins because they’re my homepage.

    Like Melusine, I’ve been looping that movie over and over and I just can’t get enough (I was really hurt by having a full lunar eclipse come to town only to be obscured by an overcast sky).

    The last time this happened to me was when you linked to the animation of the Mercury spacecraft as it left Earth.

    To Tom Epps’ comment about the top 10 pictures, I think you should have a separate category for videos/animations.


  20. Marko

    It’s overwhelming. Now I know I have to get a bigger screen (1024×768 i too small for the 20MB version).

    A question to everyone: how far and in which direction would the earth be in this frame of observation?

  21. Mark Martin


    Earth would be just off to the right, at a distance of between 4.6 & 4.7 million miles.

  22. Mark Martin

    Correction: not over 4 million miles. In the neighborhood of about 1.3 million miles.

  23. Marko

    Thank you, Mark. I’m just trying to re-enact the whole arrangement with my astronomy software and want t omake sure that I preclude the most common errors, like: Is the recording right-left reversed oder upside-down? Do I use the right time frame (7:30 to 18:00 EST/UTC/GMT)?

    I don’t know the exact position of STEREO-B at that time (still searching for its orbital parameters), so I’m guessing with trial and error. The STEREO website states that “This sight was visible only from the STEREO-B spacecraft in its orbit about the sun, trailing behind the Earth”. That was a hint in the right direction (pun intended).

    Oh, I’ve just discovered the “STEREO Orbit Tool” (linked at “Mission/Where is STEREO?”). That’s an easier way. But mine is more fun. :-)

  24. Mark Martin

    Hi Marko,

    What I used to answer your question is [1]- the date-stamp on the transit photos, and [2]- the general information given as to the spacecraft’s distance. The dates given for the photos were when the Moon was approaching its full phase, which places Earth off to one side, depending on if the solar north pole is up or down in the images. The picture was taken by STEREO-B, lagging behind Earth, which means that it’s in a slightly higher solar orbit than the Earth/Moon system. Thus, the Moon would be creeping toward the east, which puts Earth off to the right. The distance was of course given plainly.

  25. Marko

    Ah, the Moon phase, that’s clever, Mark! it makes the whole thing much easier. Thanks!

    Now I can sit back again and just appreciate the beauty of the animation. Wowww… ūüėÄ


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