Re: _Mission to Mars_

From: m (
Date: Sun Apr 02 2000 - 23:07:00 MDT

--- Danger Hull <> wrote:
> Thanks for your response. The reason I suppose we can see stars
> from the
> earth is because there are no very large objects reflecting massive
> amounts
> of sunlight in our view.

In fact at the full moon you see significantly fewer stars from earth
(OK maybe I don't get around enough :-) ),unless you look well away
from it, and even then there will be dispersed moonlight.

> >>From Phil Plait's website
> >(

> >question: have you ever seen anything like it in real life? The
> answer
> >is no. When
> >NASA broadcasts live scenes from outside the Space Shuttle, you
> usually
> >see the
> >Earth in vivid blues, browns, greens and dazzling white, but you
> never
> >see stars at
> >the same time. And if you can see stars, the Earth is tremendously
> >overexposed.
> >The reason for this is contrast. Stars are fairly faint, while the


I remember an Arthur C. Clarke story, in which TV engineers were
discussing whether to let their cameras show stars as well as the
foreground in a telecast from the lunar surface.
Clarke seemed to think that the camera actually *could* do this, I
suppose by a very rapid AGC (gain control) system.
I don't actually think this is done in RL, most video cameras would
have huge problems, although many can automatically adjust gain over
the frame as a whole, or do *some* compensation for highlights. AFAIK
the kind of contrast range between the shuttle/moon and the stars
would be too much.



Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.

This archive was generated by hypermail 2b29 : Thu Jul 27 2000 - 14:09:00 MDT