What Color are Stars?

For eons, human beings have been fascinated by the happenings of the solar system.

We have used the stars to guide our way through the seas, to predict our futures and they have been a source of entertainment during our leisure time. 

Yet, there are still many things that we do not know about those twinkling natural lights above us. What we do know is certain things such as the color of the stars. 


So, without further ado, here’s the answer to your burning question: what color are stars?


Colors and Spectral Classes

Okay, so right off the bat, you need to know that stars are usually classified into different spectral classes, ordered from cold to hot.

We’ll tell you more on that later, but here they are:

  • O - Blue
  • B - Blue/White
  • A - White
  • F - White/Yellow
  • G - Yellow
  • K - Orange
  • M - Orange/ Red

Some people may remember this in terms of an acronym, and they are also numbers from 0 to 9. As you may imagine, 0 is the hottest star and 9 is the coolest. 

The vast majority of the stars that you can see in the sky are K and M stars, so they’re pretty cool. Roughly 88% of our stars are K and M spectral class stars. The others are a little rarer than they are. 

Things That Influence a Star’s Color

Now, it may not make a lot of sense to think that stars can change color. After all, when you look at the stars with your naked eye if you go star gazing, they will usually look the same color, right?

Well, let’s think about it this way. If you’ve ever used a burner at school you’ll probably know that adding certain things to the flame can make it change color. Maybe sometimes you’ll get a more orange flame, other times a blue flame. 

Fire burns blue when it’s at its hottest temperature (pretty ironic when you consider that we think of blue as a cold color!) whereas the cooler parts of the flame are an orange/ red sort of color. 

So what influences the color of a star? First of all the temperature. As we’ve said already, the coolest stars are usually a red color, whereas orange to yellow and white are warmer. If the star is truly scorching hot then it will be blue.

The other key thing that influences a star’s color is the age of the star. A star will usually create different chemicals as it gets older, and these chemicals will burn at varying temperatures. So following on from our previous point, the stars you’re most likely to see in the sky are some of the coldest additions to the solar system

What Star Colors Can I See?

You can see a range of different star colors, though what you can see can sometimes depend on the particular season you’re in. One way to find out which sort of stars you can see at any given time, you can consult a few tools including a star atlas, astronomy software or a planisphere.

Some stars, including Polaris, can be seen throughout the whole year. This is a yellow star. You can see others such as Arcturus and Betelgeuse with the naked eye because they are so bright. Other stars like Sirius B could be too dim for you to see them properly without a decent telescope and a clear night.

The Russell Diagram and Star Types

Stars are usually classified under something called the Russell Diagram. This will usually give each star a class and a sub class. 

For instance, a younger star is usually known as a dwarf star. It’s incredibly small without a great deal of mass but they burn hot! Dwarf stars come in different colors - for instance a yellow dwarf is yellow and a red dwarf is red. 

Then you have giant stars. These are much older stars that are still pretty warm, but not nearly as much as its younger counterparts. There are a few common giants, such as the red giant.

This star has usually lost a substantial amount of heat, whereas a blue giant star is old but also very hot. Then there’s the supergiant, which is tremendously large and blue in color. 

You likely won’t see a faint or a dead star because they are, well, faint. They aren’t very bright, and are very old so they sometimes don’t even have nuclear fission.

Some faint stars are brown dwarfs, that have no nuclear fission. A white dwarf is somewhat similar to the brown dwarf but it’s still hot. There are also pulsar stars that spin very quickly. 

One unique star type is the binary star - a double star, for instance, can appear as though there are two stars directly next to each other. Have a look out for Albireo A and B if you want to see an example of this.

Or you may see an x-ray star, a star with one dead star inside. It can emit x-rays. Binary stars are generally white or blue, but they can differ in color.

Conclusion

The answer to ‘what color are stars’ is a nuanced one, as in truth they can come in a range of different colors. All stars are different - some are old, some are new. Some are hotter, some are colder.

These things can influence the color of a star, though it may not always be clear what color a star is when you are observing with the naked eye. In this case, it’s definitely worth your time to invest in a planisphere so that you can tell when certain colored stars are in the sky.

It’s also handy to get a decent telescope or stargazing binoculars. So, the next time you have a pop quiz asking you what color stars are, make sure it’s not just multiple choice as there are many different star colors in our solar system! It’s just a matter of finding them on a glorious starry night. 

Gordon Watts
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