Astronomical Darkness

[Ganymede12]

How dark is "astronomical darkness"? It can't be as soon as you can see something of astronomical interest because I can see the moon, not to mention the sun, and both are of astronomical interest. So how dark is astronomical darkness?

[Beulah]

It means the sun is sub 18 degrees below the horizon and there's no moon in the sky.

It means as dark as can be without the illumination of the closest heavenly bodies to us.

Here's something that SteveL wrote - gives you an idea of when astro dark ends/begins...

http://www.syn-ack.com/astrosigs/astrolocations.html

[Ganymede12]

I presume you meant the sun is 18 degrees below the horizon?

[Beulah]

Yep. Sorry about that, I was writing the post as the phone was ringing. Grrr.

Post has been edited.

[Ganymede12]

Thanks for the info and the link!