Top 10 Brightest Stars

Following are the top 10 brightest stars followed by the name of the constellation they are viewed in and the distance in Light years.

0) Sun
1) Sirius - Canis Major (Greater Dog) - 8.6 ly
2) Canopus - Carina - 310 ly
3) Alpha Centauri AB - Centaurus - 4.4 ly
4)  Arcturus - Bootes (Herdsman) - 37 ly
5) Vega - Lyra - 25 ly
6) Rigel - Orion (Hunter) - 770 ly
7) Procyon - Canis Minor (Lesser Dog) - 11
8) Betelguese - Orion (Hunter) - 640
9) Achernar - Eridanus (River) - 140
10) Beta Centauri (Hadar/Agena) - Centaurus - 530

How long is one day on moon?

Ever wonder how long a day is on our moon?
The day on any celestial body is defined by its rotation along its own axis (if there is any). Therefore, as the Earth rotates around itself in 24 hours, our one full day is equal to 24 hours. But our moon, rotates around its axis very slowly compared to the Earth. In fact its one rotation equals its one revolution around the Earth. It takes 29.5 earth days for the moon to complete its one rotation. And so one day on moon is equal to 29.5 earth days. And we can say that half of it would be a day  and the other half its night.
Another result of moon's rotation being as long as its revolution is that we, here on earth, always get to see the same side of the moon giving the other side of the moon its name "Far Side of the moon" (previously called Dark side of the moon; but that is wrong because it also gets the sunlight as the moon rotates).

How would the day have looked like on planet earth if we had no atmosphere?

We are so used to the idea of the day being full of light and blue skies that it is difficult to imagine otherwise. But the blue sky that we see everyday is due to the atmosphere we are lucky to have.
To get an idea of how our day would be look at the following picture from the International Space Station:

The sky is dark with a very bright sun. No atmosphere and therefore no full of light sky.