Stunning Jupiter and Io picture: here's the scoop

By Phil Plait | March 19, 2012 8:51 pm

I’ve been getting notes (like from my friend Melissa) asking me whether a picture of Jupiter and its moon Io is real or not. The answer is: kinda! And of course I’ll explain. First, here’s the picture in question:

[Click to enjovianate.]

First, let say that when I saw the picture I recognized it, but couldn’t place it. Google to the rescue! I did an image search on "Jupiter Io" — I recognized the moon as Io from the obvious volcanic plume and features on its surface — and quickly got my answer.

Basically, it’s a montage of two images, both of which are real but were taken separately. They were taken by NASA’s New Horizons probe, which passed Jupiter in 2007. New Horizons is on its way to Pluto, and flew past Jupiter to steal some of its energy and boost the speed of the probe.

The shot of Jupiter is actually a composite of three images taken in the infrared, well past what the human eye can see. That big blue spot is actually the Great Red Spot! But the scientists applied a false color to the infrared images for this picture. The different colors more or less show cloud height: high-altitude clouds are blue, and clouds deeper in the Jovian atmosphere are red.

Io is actually depicted as more true to what your eye would see — it’s shown in visible light, not infrared. However, that image of the moon was taken nearly a day after the Jupiter pictures were taken! The two pictures were stitched together later. The red spot is an active volcano on Io, and the blue swoosh is the plume of ejecta reaching well above the moon’s surface.

[Update (March 20, 2012): Apropos of this, and coincidentally, the USGS just released a global map of Io. On Google+, I posted a the Io map highlighting Tvashtar Paterae, the volcanic region erupting in this picture.]

I’ll note that the phase of Jupiter — almost half full or so — isn’t real, though. The infrared images of the planet were taken many minutes apart, and Jupiter rotates so quickly that they would’ve been blurred, smeared, if simply shown as they were taken. To compensate, the person putting the image together mathematically projected the pictures onto a sphere seen obliquely like this. In reality, the space probe was nearly directly above Jupiter’s lit side when it took those images. Weird!

Anyway, apparently this picture was posted on reddit linking to an anonymous image hosting site that didn’t have much by the way of explanation, and got out into the wild of the internet. People loved it — I mean, come on, it’s an awesome shot — but weren’t sure if it was even real, or where it came from. I’ll note that way down in the comments on that post the true nature of the picture is revealed, but not before the picture got spread far and wide. That happens on the ‘net, and I’m just glad I got people asking me about it. One of the big points of putting together pictures like this for the public is to pique their curiosity!

And I’m happy to oblige that desire to learn. Think about it: this picture isn’t a fake, it’s real, more or less, and it’s from a small spacecraft on its way to Pluto, and then out of the solar system forever. And as usual, reality is way, way cooler than fakery.

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Goddard Space Flight Center

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MORE ABOUT: Io, Jupiter, New Horizons

Comments (21)

  1. The scale is pretty funky as well- Io should be like 1/40th the diameter of Jupiter, not 1/6th.

  2. RichT

    It’s called perspective.

  3. Jason A.

    Io is closer to the camera… I don’t know if the scaling is right, but it’s not as simple as comparing the diameter of the two objects, it’s the angular diameter that matters.

  4. ethanol

    Personally I’m a bit of an image purist. False color is fine if the actual wavelengths are out of the visual range, but combining elements from false color and real color images is misleading. Also combining completely separate images to produce artificially enhanced compositions strikes me as sort of dishonest. In my book it’s acceptable to move elements to line up between different color filters, but not because you couldn’t find a shot that looked the way you wanted. This may all seem a bit pedantic, but there is just too much wonderful imagery out their to be doing things like this, especially when you run the risk of people not believing in the reality of future images. There is already a terrible tendency developing among young people who have grown up with the internet to cry “fake” when they are shown something truly amazing. NASA, which produces so much of the truly amazing, should be especially careful with honesty in image presentation.

  5. ethanol

    As an aside, the Io eruption picture is F*#%&N amazing.

  6. Dutch Railroader

    It’s possible to have a perspective that makes Io appear relatively large. What doesn’t seem to work in this picture, however, are the relative phases of Io and Jupiter. Io is more “crescent” than Jupiter. They should be the same, indeed, if any thing, Io could be somewhat closer to”last-quarter” phase, given that its relatively large size implies that the probe is pretty close to Io, yet it falls in the anti-sun direction, which means that the Io phase angle should be a little smaller… (the sun-io-probe angle is not as acute as the sun-jupiter-angle.)

  7. Emily Lakdawalla

    This particular mishmash of images was composed for the cover of the issue of Science (or maybe Nature but I’m pretty sure it was Science) in which the NH results from Jupiter were first published.

  8. Messier Tidy Upper

    @ ^ Emily Lakdawalla : Thanks for that info. :-)

    @4. Dutch Railroader : I think that crescent-er Io effect is a result of them being different photos taken on different days under different lighting conditions & astrionomical geometry! ūüėČ

    I’ve been getting notes (like from my friend Melissa) asking me whether a picture of Jupiter and its moon Io is real or not. The answer is: kinda!

    First – define “real”! ūüėČ

  9. Keith Thompson

    The first thing I noticed when I saw this on reddit is that the phases are slightly different.

    The second thing I noticed was a dim gray rectangular background surrounding Jupiter when I tilted my laptop’s display.

  10. Loud

    The blacks of the two images aren’t matched, so if your monitor isn’t too dark, you can see the rectangular seam around Jupiter plain as day… err.. night?

  11. With all the loonies out there it has become somewhat dangerous to “doctor” images for artistic reasons (hi Emily!). This is like alcohol: some can use it responsible and get their kicks out of it, others don’t take it so well.

    That said, which of these images is r e a l according to the example set by the Jupiter / Io image:×420.jpg

  12. Carey

    @7 Loud: Or if you have an LCD monitor, viewing the image at an oblique angle will reveal that rectangle around Jupiter.

  13. uncleMonty

    So if I take a false-colour infrared picture of you Phil, and mathematically warp the image onto an obese person’s body shape, and apply fake lighting to make it appear that you’re lit from the same angle as Saddam Hussein, who by the way I’ve placed you next to in this composite image, and I publish this–then this photo is “real, more or less”? :-)

  14. Dan

    Phil, have you used TinEye before? It’s a very convenient reverse image lookup that takes a bit of the hunting and scrolling out of the google image search process for you. Here is what it kicks back for the image above –

  15. Tom K

    I’d say from reading the explanation that it’s fake, more or less.

  16. Gary

    This image is a metaphor for Peter Glieck’s faked Heartland memo and Dan Rather’s fake but accurate document.

    Images like this ought to have a brief citation of the manipulation watermarked on them to prevent misconceptions and deliberate deceptions.

  17. flibbertigibbet

    Guys, guys, the big thing here is that the black rectangle that floats in between this moon and the king of planets isn’t visible in the image. WEIRD.

  18. Stuart

    Is the red spot under the plume supposed to be lava / eruption? That is amazing.

    Gary, heartlands entire existence is to fake ‘everything is ok, there are no limits to growth’. The good news is that there is enough fossil fuel to turn the atmosphere right back to reducing!

    Good news – unless you anticipate your genes outliving you.

    Are you aware that man is emitting over 42 times the planets natural CO2 emissions?

    SO long as heartland accept responsibility / liability for their actions, I have no problems. But I don’t have any kids, either.

  19. Matt B.

    @10, Loud:

    Great catch. If you copy the picture into Paint and use the paintcan to fill the black with white, it really does become as obvious as night and day.

    I can’t believe Phil didn’t mention the difference in phases. Since Io is occulting Jupiter, its phase should be the same.


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