But if you look carefully, you'll see that the stars air a whole array of different colors, and people have noticed this range of colors in the stars for a long time.

In the first century BC Chinese astronomers recorded the star Beetlejuice in the Orion constellation as having a white or yellowish hue.

But many centuries later in the year 1 50 a.

D.

Egyptian astronomer Ptolemy noted the stars readiness or red color, which is the same color it exhibits today.

While this may seem like a simple observation, this change in color over time actually indicates that the star went through a major change in its life cycle.

In general, noting the color of a star can tell us so much about its age, temperature and even its chemical composition, a good place for us to begin is by understanding what color actually is.

No, I promise.

I'm not going all philosophical on you.

I'm talking about how he characterized the color of a star in astronomy.

It's all about electromagnetic radiation, a form of energy that's all around us.

This energy travels in waves and is generally separated into seven categories, depending on the frequency and length of these waves.

On one end of the spectrum, we have the quick first of gamma rays, X rays and ultraviolet radiation.

In the middle, we have a slim spectrum of visible light, thes air.

The colors we can actually see and on the other end are the longer, slower wavelengths of infrared radiation, microwaves and radio waves.

So the visible light we see is colors is really only a small fraction of the electromagnetic waves generated in the universe.

It's useful, then, that stars emit most of their energy as visible light.

Think about turning on a gas stove at the bottom, where its hottest.

The flame burns blue and white and up at the top of the flame, where it's cooler, it burns yellow orange.

It's the same with stars.

The hotter the star, the more blue white it is in color.

Similarly, the cooler the star, the more orange or red it appears.

Astronomers use a sort of thermometer for stars.

Those stars emit multiple colors of wavelengths.

At one time, the dominant color will win out and be a good indicator of its temperature and its a sliding scale to in terms of what other types of electromagnetic radiation of star is getting off the energy conflict into wavelengths that are invisible to the naked eye, which is why it's super useful to modern astronomers to be able to capture different types of electromagnetic radiation.

They do this using different types of telescopes, for example, to detect the hottest, most energetic stars or the hot glow of a stellar nursery you'd need to filter for ultraviolet.

There are other factors besides temperature that affect the stars color, including the distance of the star from Earth and the elements it's made off.

So each element within a star is associated with a specific wavelength.

By measuring the amount of energy of those wavelengths, we can tell the amount of hydrogen, helium and other various trace elements that air in a star.

This technique is called spectroscopy.

One way to see all of the individual wavelength is to pass a star's light through a filter on a telescope that takes out all the other kinds of light.

The James Clerk Maxwell telescope does this in its own way by selecting very specific wavelengths to observe.

It specializes in those at super low energy, So we're looking at the reddest deeper than the reddest red that any human could ever see.

So we see things that are cold in space or don't admit a lot of energy, at least nearby.

So the two things that we really specialize in, our the formation and birth of stars and planets looking at the gas and dust between the stars that gives birth to new stellar systems on, we also specialize in looking at Galaxies that are very, very far away, near the beginning of our cosmic history to figure out where all of these large scale galactic structures in our universe first come from, there's a variety of different sort of hidden universes that are out there.

When we look up at the night sky, our eyes only pick up a very small sliver of the total light that's actually coming in.

We need specialized instruments to see some of the physical material that's out there, and it admits that these different wavelengths it's amazing how a different filter or even type of telescope can completely change our perception of the night.

sky.

There's actually a good example of this that you can try for yourself if you live in the Northern Hemisphere.

There's a very famous star you confined in the constellation Cygnus called Al Berrio.

You can find it at the beak of sickness, which is also the bottom of the Northern Cross.

To the naked eye.

Al Berio appears as a bright white star, but this is deceiving.

With a simple telescope or even a steadily held set of binoculars, you can see that al Berio is actually two stars, one blue and one gold.

But again, when seen together with just your eyes, it appears blue white.

It's an incredible example of how a pair of very differently colored stars can shift in appearance, depending on how we view them.

Also, fun fact that Gold Star is actually also two stars, so the next time you have a chance to look at the night sky and a good light pollution free place.

Look for Al barrio in the Northern Hemisphere, but it's the timing or location isn't right.

Every star has a color.

Some are white, blue, orange, yellow or red.

Thank you so much for watching this video about the colors of stars.

My name is Sarah Finance, and this is seeker constellations.

If you have an astronomy related question or an idea for an episode topic, let us know down in the comments below, Thanks for watching.