Frequently Asked Questions About Astronomy
How many stars are there in the Night Sky?
On a clear moonless night a person with good eyesight could see approximately 3 000 stars. At any one moment in time one can only see one hemisphere of the night sky so by observing in both the Northern and Southern hemispheres this number increases to about 6 000 stars. Most of these stars are relatively near and lie within 100 light years of our Sun.
As soon as one uses binoculars or a small telescope the number of stars that can be seen increases dramatically so a pair of 10 by 50 mm binoculars will enable you to count half a million stars.
What is the nearest star and how far away is it from our Sun?
The nearest to us besides our Sun is Proxima Centauri. It lies at a distance of 4.24 light years and forms a triple system with Alpha Centauri A and B stars. Proxima Centauri is slightly closer than its companions by about 15 000 AU, but it is a very faint dwarf star and is 20 000 times less luminous than the Sun.
What is the most luminous star known?
The most luminous stars known are R136a1 and Cygnus OB2-12 which are around 6 to 8 million times the luminosity of our Sun. This should be contrasted with the famous bright stars seen in Northern Skies like: Deneb 54 000 Lo, Rigel 85 000 Lo and Betelgeuse 135 000 Lo. In the Southern hemisphere one can see Eta Carinae, which is approximately 5 000 000 Lo and might go supernova in the next 100 years!