View Full Version : Seeing Stars

2003-Oct-22, 03:03 PM
Here's a quote from Bad Astronomy (p 160):

Some people claim that ... stars should look brighter from the surface of the Moon. That's not correct ... our atmosphere is amazingly transparent to the light we see with our eyes, and it lets almost all the visible light through ... Being outside the Earth's atmosphere doesn't make the stars appear any brighter at all.

Now here's a quote from the online users' manual (http://teyssier.nerim.net/celestia/doc/opt_other.html) for Celestia (http://www.shatters.net/celestia/), Chris Laurel's excellent freeware simulation:

On the surface of Earth, our view generally includes stars of a magnitude of +6.0 or less ... However, if you were living on a space station far above earth's atmosphere, you might see stars up to a magnitude of 9.0 with the naked eye.
Can these views be reconciled, or is Laurel just wrong? (I would not dream of entertaining a third possibility!)

2003-Oct-22, 03:08 PM
It might not be just about brightness. It's about resolution. Atmospheric turbulence may obscur dimmer stars, but the ones that are not obscurred will still be as bright.

2003-Oct-23, 09:25 PM
The loss of light intensity in the athmosphere (absorption + scattering) is around 25% (a bit less in the red range, more in the blue area of the spectrum). Also there is no light pollution (this can be scattered moonlight, not only man-made light sources)outside the athmosphere, so the stars will likely look brighter "in space".