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Posted by on Aug 16, 2016 in Tell Me Why |

Why Are Stars Different Colors?

Why Are Stars Different Colors?

Stars are many different colors because some of them are hotter than others. Stars are either red, orange, yellow, white or bluish-white. The bluish-white stars are the hottest visible stars. The coolest stars shine red. Yellow stars, such as our sun, are of average temperature.

All stars are balls of hot and glowing gases, which are made up mostly of hydrogen gas. Nuclear reactions inside the stars turn the hydrogen fuel into helium gas and energy. In the case of the sun, this energy produces the heat and light that makes life on Earth possible. The sun has a temperature of around 6,000 degrees C and glows orange/yellow.

There is another important factor that can alter a stars color. If the star has any elements in its atmosphere it can change the light wavelength and that will cause a change in the color that we measure or observe.  This may explain why there are so many different colors in the stars that are being studied.

The coolest stars are the red stars and their temperature is around 3,000 degrees C. Green stars have a temperature of about 10,000 degrees C and the blue stars, which are the hottest, are about 25,000 degrees C.

So, as you can see, the color of a star depends upon the temperature as well as any atmospheric contributions it may have to distort the measurable temperature. Scientists have developed very sensitive equipment that works with the telescopes to observe and note the rainbow colors of stars that we can see.

This is the science of spectro analysis and the scientists can detect not only the star’s color, but what the star is actually made up of. The elements of a star will help as we classify the solar systems and galaxies that we discover.

Content for this question contributed by Scott Hemphill, resident of Burgettstown, Washington County, Pennsylvania, USA