Snowball Moon, Lit the Long Way Round

Image source with more information
Credit: NASA/JPL/Space Science Institute

Emily Lakdawalla points out this gorgeous early image from Cassini's fly-by of Enceladus. One thing you'll notice immediately: stars*! Cassini was clearly using a much greater exposure than usual for this snap, but why?

It seems that Enceladus was in Saturn's shadow during much of the fly-by - in other words it was receiving no direct light from the sun. It was, however, receiving sunlight that had reflected off of Saturn's rings, off the surface of three other moons, and also light that reflected off the rings and then off Saturn's nocturnal cloud-tops. It's quite the ballet of ice and sunshine, when you think about it.

*At least, I assume they're stars. Interplanetary photography gets a bit complicated.


Bobby said...

A lot happens to light when it travels through space. I probably have mentioned this before, because it's my favorite astronomy factiod I think: There are some gravity fields in space that act as massive magnifying glasses so that when light passes through them . . . well it's like a giant telescope in space - like a visual portal - so like if you point your telescope at it from here, it like magnifies your looking power in that particular direction. ...not a very scientific description.

tinker said...

Whether they're stars or planets, the photo looks lovely - looks like a giant scoop of French vanilla ice cream.
I just realized, looking at space photos seems to always make me hungry...

Pacian said...

@Bobby: I'd call that an imprecise but accurate description of gravitational lensing. ;-)

@Tinker: Well, they wouldn't be planets, but they might be tricks of the light.

Bobby said...

Flyby Sips Saturn Moon's Geysers --Washington Post