STEREO spots Jupiter slipping behind the Sun

By Phil Plait | March 22, 2009 8:59 am

Now, as an astronomer I have to tell you: don’t stare at the Sun.

That’s because you should let NASA do that for you. When they do it, they get to see cool stuff like this:

That’s a pretty nifty animation (direct links to better quality movies: mov, hi res mov, and mpg) from NASA’s STEREO B spacecraft, currently orbiting the Sun. It shows Jupiter, with its four big moons easily visible, as it drifts behind the Sun from the spacecraft’s viewpoint. In the animation you can actually see the motion of the moons as they orbit Jupiter, too. Plus, as a bonus, a coronal mass ejection can be seen apparently gently streaming away from the Sun. Don’t be fooled, though: that is a huge blast of energy off the Sun, propelling billions of tons of plasma away from the solar surface at hundreds of thousands of kilometers per hour.

Annotated still from the animation.
Click to embiggen.

The images in the animation were taken over a 30 hour time span from March 15-16. STEREO is actually a pair of spacecraft launched in 2006 in opposite directions. They have different angles on the Sun, providing solar astrophysicists a 3D view of our nearest star. You might remember the devastating image it took of Comet McNaught in 2007, and the utterly incredible solar eclipse animation that was so freaking cool I put it in my Top Ten Astronomy Pictures of 2007, too.

STEREO has an occulting disk, literally a piece of metal that blocks the bright sunlight so that it can see the fainter wispy CMEs and normal solar corona (the dotted circle represents the size of the disk of the Sun). At the end of the animation you can see Jupiter slip behind the occulter. At some point this year, Saturn will play this same game, slipping past the Sun as seen by STEREO. I hope they catch that as well. I’m still looking for Top Ten Pictures for this year, too!

Image credit: NASA/STEREO


Comments (41)

  1. We are such clevel little apes! I love this stuff, and I am glad you post this stuff. Thank you!

  2. What’s that big black two-by four floating around there next to Jupiter? And why am I hearing Lux Aeterna on my ipod?

    Oh my…it’s full of……………….

  3. Right after posting this originally with just a still frame it occurred to me to create a video of the animation on YouTube so you could see it more easily. I apologize if people got this in their email or RSS feed more than once!

  4. Phil,

    We gotta stop posting the same thing at the same time; people are gonna think we’re twins or something. 😉

    I’ve just spent a half an hour browsing the STEREO site — there are some AMAZING things to be seen there.

  5. SWEEEEEEEET!!!!!!!!!!!!!!!!!

  6. “sorry this video is no longer available.” Drat.


    Phil Plait: “I apologize if people got this in their email or RSS feed more than once!”

    I did not get anything about this in my RSS feed; it’s been slow from Bad Astronomy, news often arriving a couple of days late, but RSS feeds from other news sources are fine. What’s going on?

  8. kevlar

    “Wheel in the sky keeps on turnin…” or, “the wheels on the bus go round and round”, depending on your perspective. But they’re definitely turning, and definitely not around us!

  9. Nice! I love the distortion at the very end.

  10. That was awesome! The motion of the moons blew me away. I can’t wait to finish school so I can afford my own telescope and I can see my very own cool space things. Someday… Sigh.

  11. video no longer available? anyone else?

  12. Synopsis

    Aww man, both the previous Stereo videos Plait linked to are gone.

  13. IVAN3MAN

    @ garth,

    No problem here. Try refreshing the page.

  14. IVAN3MAN

    @ Synopsis,

    The STEREO video links work for me.

  15. Synopsis

    I guess they’ve moved pages around since Phil made those blog posts. Anyway I found them eventually, very cool.

  16. CR

    Nope, refreshing didn’t work, either. I get “no longer available.” I’m getting that on a lot of different links on different blogs/forums. What’s up, You Tube? Sheesh!

  17. Torbjörn Larsson, OM

    Ooh, positively orgastronomical. And Saturn too? Can’t wait!

  18. Jupiter’s displacement is ~0.1 degree from the edge of the photosphere Did General Relativity displace the image to spec? Are the Galilean moons’ orbits more strongly deformed as they graze closer to the sun?

  19. IVAN3MAN

    @ CR, and garth,

    Try one of these URL links:

    Just copy-and-paste into your browser’s address bar.

    Furthermore, if in future you have the “This video is no longer available” problem, just add &fmt=8 or &fmt=16 or &fmt=18 to the end of the YouTube video URL.

  20. Gonzo

    Very, very cool. I had seen the still yesterday or something, but that animation made my night.

  21. wow! everyone I know must see this.

  22. Zippy the Pinhead

    As Opiecan says, there is a distortion at the end as Jupiter goes behind the sun. Is this an artifact of the filter or a gravitational lens effect?

  23. William Thompson

    I notice a number of questions about the distortion at the end of the movie. This is caused by the heavy vignetting just at the occulter edge. In effect, only a part of the aperture is being used in that region of the image, and the effective resolution is different in the transverse and radial directions.

  24. Tom

    Ironies of ironies, at the end of the video a scroll add appeared advertising “The UFO Hunters” on the History channel. I’ve seen some of the crap that passes for science on the History channel these days, it’s disheartening.

  25. Looks fantastic, but could someone explain.

    Jupiter is about 5 billion+ km away from the sun, how can it be so large in this pic proportionally to the sun?

    Jupiter should be 1/4 pixel and the sun’s edge almost a straight line since it is so big relatively speaking it’s curve would be indescernable.

    To put it another way – if we had a pic of Jupiter in the foreground and the sun in the background, Jupiter would be the size of the sun in this pic and the sun the size of Jupiter in this pic.


  26. David

    Why is no one else debunking this video? You can clearly see that Jupiter is only blocked by STEREO’s own occulting disk, not the sun’s disk which is the white line. When I found the video on NASA’a website they make no claim that Jupiter “went bihind the sun”. Phil, please correct yourself and straighten out the mess you’ve made!

  27. David, what are you talking about? The last paragraph is very clear on what’s happening in the video. And where is there a “mess”?

  28. Greg in Austin

    I’m sure David was being sarcastic. Even a 7th grader would know that Jupiter is farther away from the Sun than the Earth, which means it could never pass between us and the sun.


  29. Greg in Austin


    Perhaps because we’re looking at the light reflected by Jupiter and its moons, they appear larger than they really are? I’m not certain.

    How big does Jupiter look to you in the night sky compared to the moon, or the sun?


  30. @Greg, @David, @Phil

    I must agree with David – Jupiter is only slipping behind the occulting disk of the spacecraft, not the Sun as such – if the sun is the white line overlay.


    Jupiter needs 160x magnification to see the disk properly, while the moon is massive at 1x. The Sun is rather larger than the Moon.

    I’m sure this movie is authentic, there’s just a few issues that needs to be cleared up!

  31. Greg in Austin

    @Hein, @David,

    OK, Now I see what you’re saying. I would mostly agree that if the white line represents the surface of the sun, then it does not look like Jupiter will pass behind it. However, Jupiter is clearly passing behind the sun’s atmosphere and ejecta, and if the disc were not there, Jupiter would seem to pass behind the sun.

    As to the size of Jupiter and its moons, from the STEREO caption for the video,

    “Jupiter itself is largely saturated in the movie, to bring out the moons and the faint solar corona.”

    In other words, its much brighter than normal in this video, which makes it look bigger. You don’t need 160x magnification to see its moons. I’ve observed Jupiter and its 4 moons with my 12×50 binoculars.


  32. Well, it’s all a matter of perspective 😉

  33. Hi. I found it humorous you found this result days before I did… given I work with STEREO. The power of journalism! (I do give you the credit for ‘the kill’ in my writeup at As far as the Jupiter-Sun-ejecta position, the CME is not towards Jupiter in any meaningful sense, since the CME is still close to the Sun– within 4 solar radii, else it would not be seen by Cor1. STEREO is, over 2 days, nearly stationary, and while the Sun is rotating it’s also stationary, so it is Jupiter’s orbital motion doing the movement seen. Hope that helps in framing this.

  34. glenn

    i thought planets went around the sun counterclockwise?

  35. I wonder what Einstein would say if he could see this


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