Comments

1. blf says

   April 19, 2017 at 12:47 pm

   Except for being much more perfectly spherical and not quite as slimy, that looks remarkably like one of the oysters I had for lunch today. The nice vin may be helping this resemblance…

2. Marcus Ranum says

   April 19, 2017 at 7:45 pm

   What is the background?

3. suttkus says

   April 20, 2017 at 1:21 am

   I am not an astronomer, but… Europa is close enough that it would move considerably from Hubble’s frame of reference in the time it would have taken to make the picture. So, Hubble would have had to move with Europa to make the image of Europa sharply focused. That makes the background blurry.

4. Johnny Vector says

   April 20, 2017 at 7:12 am

   You don’t have to be an astronomer to see that the background blurriness is not motion blur. Also, that background is pretty obviously glued on with Photoshop (or the GIMP).

   Also also, I have serious doubts that that’s a Hubble image at all. Let’s see, the diameter of Europa is 3000 km. Hubble’s primary is 2.4 m diameter, so at a 400 nm wavelength it has a diffraction limit of 1.5 x 10^-7. Multiply by the distance to Europa (6.3 * 10^8 km at closest approach), and you have a resolution of 100 km. That means you should only see 30 pixels (at best) across the disc of Europa; this image clearly shows far more.

   And, yup, that image is from the Galileo spacecraft. The background is from Hubble. Most of what you see in the background is detector noise. The white blob at about 8 o’clock is an erupting plume. They pasted the Galileo image on top of the Hubble image, in a sort of “Mike’s Nature trick” to show where on the moon the plume is. (I assume they aligned it correctly.)

   So, it is a Hubble image (taken with STIS, Space Telescope Imaging Spectrometer — Yay STIS repair!) plus a Galileo image.

   Here’s a page showing more clearly what comes from where: http://hubblesite.org/image/4016/news_release/2017-17