The Moon - weird image

[fred]

Look at this image of the Moon as seen from Earth. Why is there a bright white spot in the middle?

Because the sun is on the other side of the Moon, shouldn't the Moon be completely dark as seen from Earth?



I've never done this before so I don't know if this image will appear. If it doesn't, go here: http://tinyurl.com/isv6

http://tinyurl.com/isv6

[fred]

Ok, well that didn't work

Oh well, never mind.

[selden]

Fred,

You might try posting a Celestia URL so others could try going to the same viewpoint to see if they can see your problem.

In Celestia, the "Ctrl-Insert" command usually writes Celestia's current state to the clipboard. You can then use the right-mouse-button menu to "paste" that URL into your posting.

Does this help?

[fred]

Ok, thanks. Let's try this. I went back to the (almost) exact same spot as yesterday and tried creating the URL. Hope this works:

cel://SyncOrbit/Sol:Earth/1994-05-10T17:23:05.29904?x=hJBI7pnP5GOzDA&y=Tu4+WzZeBg&z=bX/6ErXUWTUM&ow=0.725507&ox=-0.214222&oy=0.277822&oz=0.592084&select=Sol:Earth:Moon&fov=25.253553&ts=0.000000&rf=1380088&lm=1244288<d=0&rf=38167&lm=18

The URL is very long, but this one should work too:

http://tinyurl.com/itsy

I am about 4000 km above Earth's surface, looking towards the Moon. The Moon is dark except for a big bright white dot in the middle. You see it better with full screen. This is the "New Moon" so as seen from Earth, the Moon is completely dark because the Sun is completely on the other side.

[fred]

Well, the tinyurl didn't work but the long url worked

one out of two isn't bad!

[selden]

That's the moon's albedo value confusing things.

When an object is being drawn smaller than a particular angular diameter (too small for surface features to be seen). the dot representing it is drawn with a diameter and brightness which is proportional to the albedo value in its SSC definition. (That's the only time the albedo value is used.)

Unfortunately, it seems to me that both the code for drawing the dots' brightness and the actual albedo values in SOLARSYS.SSC need to be modified to be compatible. Moons, for example, are being drawn much too bright.

[fred]

Ok, thanks. I think I understand. Do you think that this is something that can be fixed?

Look at this image of Earth as seen from Mercury. We can clearly see the Moon orbiting Earth. I would think that standing on Mercury and looking at Earth, we would just see a blue dot and no moon around it unless we use a telescope. But maybe I'm wrong too.

cel://Follow/Sol:Mercury/2003-09-03T19:40:45.61875?x=aGelgg0oC4vCDA&y=9Rh4MYTkWjX//////////w&z=oeTaIkmzojYE&ow=0.669492&ox=-0.004185&oy=0.741240&oz=-0.048235&track=Sol:Earth&select=Sol:Earth:Moon&fov=26.141790&ts=0.000000&rf=982764688&lm=5<d=0&rf=38151&lm=16

I love this program anyway, I just find that seeing the bright Moon when it should be black or just not visible is a little weird. If it is something that can be correctly to make the simulation more real than it would be great. If not, then it doesn't really matter.