Saturn in Methane Bands
Well, here's a thing that was unexpectedly well-received over at my Twitter account. Originally I posted it as an amusing joke, but people loved it, so I finished processing it by getting rid of all the cosmic rays and trying to align the disturbances in some of the clouds near the north pole.
Why are the rings neon green, you ask? This is just how the colors end up looking when I try to white balance the cloud tops of Saturn in a given set of narrowband filters specifically designed to single out certain aspects of methane. In all of these filters, the rings are very bright; in fact the rings are so bright that they are lightly saturated (filled to completely white) in some places. However, Saturn's clouds were very dark in the middle filter, which goes in the green channel, so when I tried to brighten the clouds to match with the red and the blue channels, the rings changed from their normally bright, whiteish color to a fluorescent green.
Bright moons visible in the image include Mimas at the lower left, Enceladus at the upper right, and Tethys at the middle right. There are also two faint moons just barely visible, both very close to the rings: Janus near the top of the rings, and Epimetheus centered at the bottom of the rings. I am not 100% sure that they are them, but given their positions and relative brightness to one another, this is my best guess.
These observations were originally taken on 2015 June 29 to study the storms, which were spotted by tireless amateur astronomers, near the northern pole. You may recall that Cassini was still operating at that time. However, the probe was not positioned optimally to capture the disturbances immediately, and it was worried that they would be largely missed. Hubble's Director's Discretionary budget was utilized to take the imagery relatively quickly. Presumably this means someone else's observations were partially cancelled or pushed around since Hubble's schedule is packed tightly, but this is how the cookie crumbles.
This image is scaled by 200% of its original resolution and then an unsharp mask was applied for sharpening.
Red: WFC3/UVIS FQ937N
Green: WFC3/UVIS FQ889N
Blue: WFC3/UVIS FQ727N