On 8 Jun 2004 16:05:47 -0700, LSL wrote:

Hello All,
Not really an amateur - more like a casual observer with an interest -
please forgive the intrusion.

I've been watching the Cassini stuff, and something struck me that
I've never really thought too much about before, so I'm hoping this
isn't the proverbial stupid question!

When I see these images of planets within our solar system, why do I
never see stars in the backdrop (at least that I can remember?)
[snip]

Exposure time. Stars take time to show up on film (and CCD). The light
needs to accumulate.

The exposures of planets and the like are pretty short, especially those
of a full moon. There's not enough time for most stars to begin showing
up.

You can replicate it yourself by taking a picture outside on a clear
night. Make sure the sky is visible in the frame, and use either bright
floodlights or a flash. The exposure will be short, and you won't see
many (or any) stars.

I expect it now seems obvious.


--
- Mike

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