Io and Europa, on the way out

By Phil Plait | April 2, 2007 1:50 pm

This image is way, way cool:

It shows Io and Europa, Jupiter’s moons, and it was taken by the New Horizons spacecraft on its way out of the jovian system. I could explain it in detail, but Emily already did, and since I stole the image from her, I should at least let her do the talkin’. But go read it; it’s interesting.


Comments (17)

  1. Grand Lunar
  2. Wanzewurld

    We’ve come a long way since the 200 inch telescope at Palomar was the premier eye on the sky! I’d give a gold-plated Bush (LOL) to know what the next 25 years will bring. Maybe I’ll see it as I’m 60 now and been interested in astronomy and physics since I was in grammar (Does that date me?) school… Elementary school now to you young’un’s.
    Thanks for sharing and for your timely comments

  3. Doug

    Hard to imagine that the same species that pulled this off also produced…Pat Robertson.

  4. wright

    What an image. Just mouth-watering, mind-blowing beauty.

  5. Gorgeous picture, I say.

    I am particularly intrigued that the picture was suggested by “a space enthusiast” who had looked at trajectory data and suggested a point at which an interesting picture could be had.

    Unlike a lot of photography that takes place as it unfolds right before the lens, with the photographer making a split-second decision to press the shutter release at the ideal moment, having to anticipate what things might look like some time in the future adds quite a difficult element to this type of photography.

  6. Matt Johns

    OK, somebody please reply to this or I will be bugged by this picture for days: is it in false color or are those the same images that people’s eyes would see if they were somehow tagging along for the ride on new horizons? I know that false color is used a lot, but seeing red hot lava and a neon blue plume would be even more amazing if I knew that that is what it really and truly looks like.

  7. Matt, it’s false color. See the original press release at, the red/green/blue colors are using wavelengths 850, 620 & 480 microns.

  8. Ed

    Gordan: not 850, 620 & 480 microns but nanometres. If they were microns they’d be far infra-red (corresponding to temperatures not much above absolute zero) whereas nanometres are pretty much visible light as the article explains.

  9. Ed, right you are, my bad. Sorry, a case of automatism I guess… :)

  10. John Oliver

    A way cool image that definately goes into my classroom lecture presentations.

  11. Melusine

    Excellent explanation of the photo by Emily. And yeah, this was interesting:

    This particular Kodak moment was suggested by space enthusiast Richard Hendricks. These kinds of pictures are of the greatest benefit to the public — it seems fitting that it’s a member of the public who did the work to find out and suggest to the New Horizons team when to take them.

    She mentioned him in a previous blog entry, too, regarding Saturn’s hexagonal pattern. He’s from Austin apparently.

    I found this photo of the Tvashtar’s Plume back in early March to be very cool; this latest photo is another great shot.

  12. Tom

    Nice. I need to bookmark Emily’s blog and visit that more often. There seems to be a lot of stuff on there that isn’t easily found on the “Official” NASA sites. Seems that the MER team isn’t doing much with the rover site other than a few updates now and then, and the usual raw photos. Sure, I’m not complaining, but keep it more interesting! The general public thinks the rovers have returned to Earth by now.
    (yes, someone DID ask me “when are they coming back”) I’m not smiling I’m wincing. *ugh*


  13. Donnie B.

    I was glad Emily included a description of the “Jupitershine” illuminating Io but not Europa. I’d noticed that and guessed the explanation, so it was neat to learn I’d figured it right.

    I saw the Tvashtar plume, of course, but the other two were pretty subtle and I wouldn’t have noticed them without the descriptions.

    Very awesome image! And, by the way, Doug… LOL!

  14. Irishman

    Matt Johns, they are false color, but not dramatically so (such as three shades of IR). Your eyes would see something similar, a little more contrast between the two, and the night side looking a little less green.

  15. John23

    Cassini takes shots like this around Saturn all the time.

  16. SF Reader

    I wonder if we would have twigged to elliptical orbits, solar system geometry, and gravitation in general sooner if we had had multiple moons with visible disks, so that we would see them in various phases at the same time.

    Io and Europa are in identical phase only because of the angle of view in this photo; from Jupiter (or an inner orbit) their phases would’ve been very different.

  17. Bougainville

    I thought at first this was an April fool; it seemed too cool to be true.


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