A glance at the night sky above Earth shows that some stars are much brighter than others. However, the brightness of a star depends on its composition and how far it is from the planet. Astronomers ...

Hubble proved Andromeda is a separate galaxy by identifying a Cepheid variable star within it. Cepheid variables have a period-luminosity relationship: longer period means greater brightness. Knowing ...

Stars come in all colors and sizes. But our eyes limit us to seeing very few of those colors. And the range of apparent magnitudes of stars we can see with our naked eye is also rather limited.

The first observer to catalog differences in star brightnesses was Greek astronomer Hipparchus. He created a catalog around 135 b.c. of roughly 850 stars divided into six ranges. He called the ...

Humans have been utterly fascinated with the night sky and the millions of stars sprinkled throughout the huge expanse. Out of the numerous stars, some are brighter than others, and closer to the ...

With the naked eye, humans can see up to 3,000 stars under optimal conditions (clear skies, free from light pollution). Among them are very bright stars of different colors. Some are more visible than ...