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Posted by on Mar 18, 2015 in TellMeWhy |

Why Are Some Stars Brighter than Others?

Why Are Some Stars Brighter than Others?

Why Are Some Stars Brighter than Others? Stars may appear very bright because they are bright, or because they are close to the Earth. The stars are not all at the same distance from us. Some stars are closer and some are farther away. The closer a star is to us, the brighter it will appear.

Stars are actually great balls of glowing gases – their brightness depending upon their size and temperature. Larger stars usually shine more brightly than smaller stars do. So, how bright a star appears in the night sky depends on its size and how far away from us it is.

Astronomers measure the brightness of stars by magnitude. A bright star may be zero or first magnitude. Stars that are just visible to the naked eye are called stars of the sixth magnitude. Each magnitude is 2 ½ times brighter than the next magnitude. Therefore, a first-magnitude star is 100 times as bright as a sixth magnitude star. Now you know why are some stars brighter than others.

Which star shines the brightest? Sirius A and B. The brightest star in the sky is Sirius, also known as the “Dog Star” or, more officially, Alpha Canis Majoris, for its position in the constellation Canis Major. Sirius is a binary star dominated by a luminous main sequence star, Sirius A, with an apparent magnitude of -1.46.

Do stars shine brighter before they die? Yes. A star like the Sun spends about 10 billion years on the main sequence. After that, when it’s running out of hydrogen fuel in its core, it swells into a much brighter red giant star for a relatively brief time before dying.

Content for this question contributed by Brian Brogan, resident of Cincinnati, Hamilton County, Ohio, USA