Big Picture: The Sun

By Phil Plait | October 13, 2008 11:41 am

The Boston Globe’s pictorial feature The Big Picture keeps delivering! This time it’s the Sun.

STEREO image of the Moon transiting the Sun

That picture, taken by the STEREO spacecraft, shows the Moon transiting the Sun (and I liked it so much it was part of my Top Ten Astronomy Pictures of 2007), and is part of a jaw-dropping video.

The other images of the Sun posted at The Big Picture are just as incredible. Sunspots, flares, coronal mass ejections pummeling comets… do yourself a BIG favor, and go check them out.

CATEGORIZED UNDER: Antiscience, Pretty pictures

Comments (35)

  1. those are truly awesome. thanks!

  2. Viewer 3

    What’s always fascinated me is how powerful the sun is. It’s easy to just think “Oh, it’s a star, of course it’s powerful,” but going outside on one of those cloudless summer days when you can feel the sun completely baking you, when it feels like it’s burning right next to you and you can’t be out of the shade for too long without getting severely burned… and then realizing that it’s millions and millions of miles away. And THEN realizing that we have an atmosphere protecting us, and it STILL feels like standing inches from a giant campfire (and then, of course, realizing that our sun is a relatively small star). Thinking about how that heat travels millions of miles through the near-zero temperature of space, finally arriving at Earth only to barely be able to trickle through our atmosphere and barely touch us… and how “barely touching us” means being oppressively hot and burning the hell out of us.

    Of course all of this is factual, but when you go through life like most normal people thinking that the sun is just the sun without really stopping to think about the true power involved… well, it can be fairly fascinating.

  3. I’m probably a complete idiot but I can not for the life of me picture the geometry of the situation which would give rise to the STEREO image of the lunar transit. I’m having trouble figuring out how to get the moon to appear smaller w/o changing the apparent size of the Sun and still be able to look along a line-of-sight that puts one in front of the other.

  4. kuhnigget


    It’s the affect of a “zoom” lens. Objects at different distances are enlarged equally, giving the impression that the huge gaps between them are being compressed, too. Can be used to great affect in movies. Of course I’m sure someone’s got the exact technical lingo to explain it…

  5. kuhnigget

    BTW, that photo number 4 is fan freakin’ tastic! After seeing blurry images of the “granules” all my life, now to start seeing their 3-D structure is incredible. Can you image what it would look like to actually be that close to the surface of the sun? Wow. Ouch, but wow.

  6. Trebuchet

    Christopher, go to NASA’s Stereo site (as easily found by Google) and use the “Stereo Orbit Tool” for February 25, 2007, to see the alignment of the “B” satellite, the Earth, the Moon, and the Sun.

  7. redx

    Kuhnigget, you are talking pretty much about depth of field, I believe. Chris, I think, is just having a hard time wrapping his head around the idea that the distance between Stereo and the moon is pretty much insignificant compared with the distance between Stereo and the sun.

    A large proportional change between the camera and the moon is a minuscule change between the camera and the sun. Thus the apparent sizes change disproportionately.

  8. Quiet Desperation

    That’s no moon!!!!!!

    (someone had to say it)

  9. kuhnigget


    No, depth of field refers to the zone in which objects will be in or out of focus. I was referring to the affect of a long focal length lens (“zoom lens”) that magnifies objects. A side-effect of magnification is the illusion that objects at different distances appear to be “compressed” together. That’s what’s going on with that sun picture.

    Although in rereading Christopher’s comment, I realize he was talking more about the tiny size of the moon relative to the apparent size of the sun. Which, as the info you pointed out explains, is due to the fact that the spacecraft is about a million miles away, or roughly 4 times further than we are to the moon. Instead of a nice neat “total eclipse” when the two are lined up, the spacecraft sees a transit.

  10. Gary Ansorge

    Ah, the power of the sun,,,it never sets, never dims, cranks out 1350 watts/m^2 (at earth orbit) and will last for several billion years. What can we do with that?

    Well, here’s a digg connect to a letter sent by Ben Bova to the next president(from my ssi yahoo group).

    GAry 7

  11. Fizzle

    The CME hitting the comet is just to cool!

  12. PhilB

    WOW! Out of curiosity, is there any kind of scale reference for the close-ups of the sunspots? It’s just fascinating to think of how huge those “granules” really are.

  13. It’s amazing how frightening and awesome the Sun truly is. I’m at work and I was just staring at those pictures in sheer amazement. Damn I love this stuff. I need to find my telescope like right now

  14. Absolutely fascinating !! very very impressive graphics.
    My jaw dropped to China !

  15. I read the above post ( in dutch ) and thought i’d translate it for you folks that are wondering what he said .

    “The sun, our most of close ASTRE, how nicely `cannot be ie, however?! On them in the heading The piglet Picture have placed 21 marvellously beautiful photograph of the sun, which you do lick one’s lips really. Above photograph is of it a one, sunspot among granulae on the sun washing by areas. Taken in H-őĪ on 4 augusts 2003 with the Swedish 1-m Solar Telescope (SST). Of I have earlier also already indicated on a splendid serial concerning the Space shuttlecock Atlantis. One photographs say frequently more than thousand words and that really applies to these serials. Source: Bath Astronomy “

  16. Jim Shaver

    I think I feel a bit like Christopher, in that I’m not sure I understand the geometry and dynamics of the video. Assuming north is up, the sun is spinning counterclockwise when viewed from above (north of) the solar system. Similarly, from above, Earth is spinning counterclockwise, and the moon is orbiting Earth counterclockwise. So as viewed from Earth, the moon is moving from right to left when it is between the sun and Earth.

    But in the video, the moon transits the sun from left to right, opposite to the motion I would expect from Earth’s view. So what gives? If the STEREO spacecraft orbits the sun synchronously with Earth, the apparent left-to-right movement of the moon can’t be due to movement of the spacecraft relative to Earth. Is the moon on the far side of Earth (away from the sun) during this transit? That would explain the left-to-right movement relative to Earth, but it would also make the moon closer to the spacecraft, which would make its image larger, not smaller. It could be that the spacecraft is still farther from the moon in this position than the moon is from Earth, and that a moon-sun transit would create a smaller image of the moon if the moon were on the near side of Earth.

    However, I’m not at all confident that I got the geometry right. Anyone else know?

  17. Robbie “Emission in this spectral line shows the upper chromosphere at a temperature of about 60,000 degrees K (over 100,000 degrees F).”

    Ahhh!!! Another person said degrees Kelvin!

  18. IVAN3MAN

    The reason why the Moon appears small in the above picture, less than 1/4 the size seen from Earth, is because the spacecraft-Moon separation is over four times the Earth-Moon distance.

  19. Roger Wilco

    Great, but why is this linked to Antiscience BA??

  20. IVAN3MAN

    I’ve just now observed that kuhnigget already said that.

    Note to self: Refresh the bloody page before submitting a comment.

  21. kuhnigget

    So there, Ivan. ūüėÄ

  22. @ Jim Shaver

    The above picture/movie was taken by the STEREO B spacecraft on 25-Feb-2007; six days later, there was a Full Moon and a total lunar eclipse. Therefore, the Moon was, at the time the picture/movie was taken, just past First Quarter and was proceeding in its orbit from left to right, as seen from behind the Earth looking down from north.

    Click on my name for the link to the Astronomy Picture Of the Day feature.

    So there, kuhnigget. :-)

  23. What a truly neat video! Wow. Just wow.

  24. Ah ha…I get it! My problem was two fold. Looking at the “current position” of the spacecraft, I assumed they had always been trailing and leading the Earth by ~30 degrees. Using the Stereo Orbit Tool, I see that STEREO B was “behind” Earth on the date the picture was taken, the only place it could be to see a lunar eclipse. I also forgot that how much a change in distance corresponds to a change in angular size is actually dependent on the distance. If theta = s/r then d(theta)/dr = -s/r^2. Which is why the apparent size of the moon is decreased much more than the apparent size of the Sun.

    I now have a nice red welt on my forehead from me smacking myself there. :-)

  25. Sorry, my previous post should say “lunar transit”, not “eclipse”. Yes, I’m nitpicking myself. I’m like that.

  26. Robbak

    Is it just me, or is there some lensing going on in that video? Its faint, but it does seem that the solar image shifts slightly as the moon passes it.

    But I would assume that the moon is far too light, and the distances far too small, for any gravitational lensing to occur.

    Its probably just an illusion. I cannot detect it if I cover up the moon’s path with a piece of paper, but maybe it is just too small to detect with the eye on such a small video.

  27. ND

    They’re all great but I hadn’t seen #8 before. That’s unique.

  28. kuhnigget
  29. HAWESOME!!!1!!ONE!! (sorry, but I guess I’m still a geek :-)

    Questions and comments, as always, and I’ve actually got the time to post!

    If light at 171, 195 and 284 Angstroms best shows temps around 1M, 1.5M & 2M (Kelvin?), respectively (per image #11), why does the wavelength of 304 (presumably Angstroms, since it mentions UV light) in image #19 show gasses at 60K degrees? Since this apparent (to me, anyway) discrepancy doesn’t seem to be a unit issue (degrees C or F instead of Kelvin (not degrees :-)), is it because we’re looking at ionized Helium (instead of the presumed Hydrogen)?

    The CME blowing away the comet’s tail is so fascinating that I paused to watch for a few minutes before continuing. Of course, it took me a while to actually get through the entire page.

    Anyone know why the seismic waves in image #8 accelerate?

    Thank you for the Ben Bova article link, Gary 7!

    BTW, I prefer Rankin to Kelvin. Degrees Rankin ūüėõ – g^2

  30. Al

    I think the words “telephoto compression” are those Kuhnigget was searching for…

  31. Jim Shaver


    Thanks for the answer. Guess I wasn’t quite so confused after all!

  32. Grand Lunar

    That’s one of my faves. Who knew something so common would still look so neat?


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