Enceladus emmiting water vapour

[caleb]

I only heard of this breifly and I was hoping it could be seen through a 100-200X telescope.:help:

[goober]

Funny, I was listening to Astronomy 161's podcast on this today. I had no idea there was volcanism on this moon.

Can't help you with seeing it though. Check out Cassini images, I guess.

[ngcles]

Hi Caleb,

Sorry to disappoint you but no, there is no hope at all of seeing this new feature on Enceladus.

Enceladus is just over 500km diameter and with Saturn, is currently about 850 million km away from us on Earth. The planet Saturn is (roughly) 120,000 km in diameter and Enceladus is therefore only 1/240,000 times as big.

As the disc of Saturn currently subtends roughly 20 arc-seconds diameter of sky, Enceladus itself is only 1/240,000th as big as Saturn and therefore cannot be resolved _as a disc_ in any telescope at any magnification -- let alone seeing any detail like a plume (tiny, tiny, tiny detail). Remember this water plume wasn't discovered until the Cassini spacecraft found it while passing Enceladus very close by in the last year or so.

However, in good sky condiitions, you might be able to see Enceladus with an 8 -10" 'scope when it will look like a very,very faint star next to Saturn's rings. Despite its very small size it has a relatively high albedo and therefore reflects a lot of the light that falls on it resulting in a pretty reasonable magnitude of +11.7. Enceladus orbits not far outside the main rings so it can be tricky to both see and identify/distinguish from its siblings.

Best,

Les D
Contributing Editor
AS&T