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| Space on Jul 04, 2009

Do stars shine in color?

Stars actually shine in different colors, like red and blue – it’s a reflection of their varying internal temperatures.

Yes. Look on a dark night, when the moon is down. Look from a country location. Compare one star to another. If you look closely, you can discern the colors of the stars.

Star colors stem from conditions surrounding a star at its birth. Stars are born with varying amounts of mass. Maybe you’ve heard that our sun is a medium-sized star – many stars are less massive than our sun, and some stars are much more massive.

The most massive stars have the most powerful self-gravity. Their own gravity squeezes these stars inward – heating them up inside to extremely high temperatures.

How hot a star gets determines its rate of thermonuclear fusion – that’s the process by which stars shine. The most massive stars have the fastest rate of fusion, and these stars shine most brightly.

Meanwhile, the least massive stars have relatively weak gravity. They’re cooler, so they shine more dimly. Star colors are related to star masses and star temperatures. Just as something white hot on Earth is hotter than something red hot, so white stars are hotter than red stars. And blue stars are the hottest of all.