Jupiter’s Moon Plays Hide-and-Seek with Hubble

NASA’s Hubble Space Telescope has caught Jupiter’s moon Ganymede playing a game of hide-and-seek. In this crisp Hubble image, Ganymede is shown just before it hides behind the giant planet. Images like this one are not only gorgeous and enjoyable to look at, but are also useful for studying Jupiter’s upper atmosphere. As Ganymede passes behind the giant planet, it reflects sunlight, which then passes through Jupiter’s atmosphere. Imprinted on that light is information about the gas giant’s atmosphere, which yields clues about the properties of Jupiter’s high-altitude haze above the cloud tops. And because Hubble’s view is so sharp, we can learn more about Ganymede as well. Visible are several features on the moon’s surface, most notably the white impact crater, Tros, and its system of rays, bright streaks of material blasted from the crater. Tros and its ray system are roughly the width of Arizona. Hubble has amazing eyesight!

And there’s a movie, too!

More about Ganymede and Jupiter…

Composed of rock and ice, Ganymede is the largest moon in our solar system. It is even larger than the planet Mercury. But Ganymede looks like a dirty snowball next to Jupiter, the largest planet in our solar system. Jupiter is so big that only part of its Southern Hemisphere can be seen in this image.
Ganymede completes an orbit around Jupiter every seven days. Because Ganymede’s orbit is tilted nearly edge-on to Earth, it routinely can be seen passing in front of and disappearing behind its giant host, only to reemerge later.

The image also shows Jupiter’s Great Red Spot, the large eye-shaped feature at upper left. A storm the size of two Earths, the Great Red Spot has been raging for more than 300 years. Hubble’s sharp view of the gas giant planet also reveals the texture of the clouds in the Jovian atmosphere as well as various other storms and vortices.

This color image was made from three images taken on April 9, 2007, with the Wide Field Planetary Camera 2 in red, green, and blue filters. The image shows Jupiter and Ganymede in close to natural colors.

Source: Hubblesite

16 Replies to “Jupiter’s Moon Plays Hide-and-Seek with Hubble”

  1. The video I saw confuses me a bit. Jupiter is orbiting about itself but one can’t see any of the features ON the planet move!! The giant red spot and, well, everything seems to be stationary. Why is this?

  2. This has to be a hoax. The animation is really smooth, like its playing real time, but everything is too fast. At that speed Jupiter would fully rotate in minutes, not 8 hours. For so much rotation and motion it would need to skip WAY more frames than it plays, yet this is 30 fps smooth. And how could Ganymede be so big? Would an object less than half the size of Earth and over a million km behind the planet really appear so large? Also, I’m not so sure that the moon is shaded consistantly with Jupiter. It looks to be a pretty crisp disk where Jupiter is showing its night side. And at that angle, why would the moon not be in shadow? The Sun light seems to be coming more from the left (hence the contrast of the night side on the right that the moon is slipping behind). That would put Jupiter between the Sun and Ganymede, yet Ganymede is getting full Sun light.

  3. Steven, your observation, which was pretty good, could be explained by this being a 3D animation. If a full image of Jupiter (obtainable at the JPL site) was to be wrapped around a 3D sphere and that sphere was set to rotate then you would see the planet turn but the features could not move as the surface would be a static image. It also seems very suspect that the red spot – the feature everyone associates with Jupiter – just happens to be front and center for this.
    Anyway, if anyone is interested, in the half hour or so since my other post I made an animation of Jupiter that looks very similar except its not Ganymede being eclipsed – its Titan. I need to reduce its file size but when I do I’ll post it somewhere.

  4. Cheers Steve.
    So in short, the whole video was fixed/fake. Why would NASA do this then, aesthetic reasons? Let us know when that video of yours is available online.

  5. Wasn’t sure anyone would respond, I hate to sound like a Moon landing conspiracy kook or something. Here’s the animation I made (it uses the afore mentioned image of Jupiter):


    I tried this in ray trace mode, when you don’t ray trace objects will be shaded but can’t throw a shadow on another object. In ray trace mode Titan did not appear, it was hidden by the shadow of the planet. Why would NASA do this? For that I have no answer, I’d like to think it wasn’t really them.

  6. Ganymede is a gem in that it is the only satellite in the system where interspecial prostitution is not only legal but hardily condoned.

  7. @yoshi LoL!

    In some respects Steve, your hoax looks more convincing than NASA’s(assuming it is one, and I’m not really saying it is 🙂

    Like I said I think they might have done this for aesthetic reasons but I too would like to think it wasn’t really them.

  8. I’m with the Capricorn One fans.I was so looking forward to seeing the vid but it is clearly faked.Compare with ANY other time lapse of Jupiter showing the same amount of rotation will clearly show major amounts of turbulence within the ringed bands in both directions.NONE?
    Guess the wind just dropped a bit huh?

  9. I see the words “fake” and “hoax” used a lot here.
    If I agree, then I must examine my work ethics…. because it seems that that I make my living as a professional hoaxer and faker.

    I make animated special effects for movies. They believe I make “simulations” or “visualizations”. Thanks be to Goodness, they don’t know it’s all fake and hoax… instead of paying, they might sue me….


  10. A friend and I had some exchange about this yesterday. To try and explain things better he sent some stills from the observation. I can say as a professional graphic artist and developer of 3D imagery and animation that I have no doubt the images were completely legit. But they do not seem to match the animation. I can bee features changing between frames (there were 6 I think) and the stipes on the planet look to be at about a 40 degree angle to the path of Ganymede. THAT makes sense, but on the anim not only is there none of the expected activity on the planet, the path of the moon and the gas bands are both very much horizontal (not at an angle to each other).
    I think the conclusion here is obvious, the observation did really happen and was well documented. But for whatever reason the animation is a simulation of that event. Maybe “faked” is harsh, “simulated” seems more on target.

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