The night sky is full of countless wonders, and one of the most incredible is the star we called Polaris. Also known as the North Star, this particularly bright star has been used in navigation for centuries.
We know some information about Polaris, but not everything. Generations of humans have looked up in wonder at the star.
So let’s say you’re trying to determine what color Polaris is – how can we know the color of something so far away? Why does it appear white to the human eye?
If you’re wondering about this, then you’ve come to the right place! In this article, we’re going to explore the color of Polaris as well as some other general facts about this iconic star.
What Is Polaris?
Polaris, also called the North Star, is the brightest star in the Ursa Minor constellation, the Little Bear. It is located approximately 434 light-years away from Earth and has a luminosity of 4000 times that of our star, the Sun. If you are wondering how we determine the distance to stars see How Far Away Are Stars.
Polaris is a notable star because it appears stationary to us when we look at it from our vantage point on Earth, while all the other stars appear to rotate around it. If you wish to discover why stars appear to rotate around Polaris, see What Direction Does the Earth Rotate.
Polaris has been an important anchor for navigation throughout human history because it sits nearly directly above the North Pole.
This means that it can be used to find what navigators call due north, making it an essential tool for explorers, hikers, sailors, and anyone who has needed to navigate by way of the stars.
What Color Is Polaris?
Polaris appears white to the naked eye, but in reality, it is a multiple-star system consisting of three stars. The primary star, Polaris A, is a yellow supergiant with a surface temperature of approximately 6,000 Kelvin.
The two companion stars, Polaris B and Polaris Ab, are much dimmer and smaller than Polaris A and are difficult to observe without a telescope.
So why does Polaris appear white instead of yellow? This comes down to how humans perceive color. Our eyes have three types of color receptors, or cones, that are sensitive to different wavelengths of light – red, green, and blue.
When these cones are stimulated in different combinations, they create the perception of different colors. White light is created when all three cones are stimulated equally.
Polaris appears white to our eyes because the light from the three stars is blended together, stimulating all three cones equally.
The yellow light from Polaris A is balanced by the blue light from Polaris Ab and the dimmer light from Polaris B, creating the perception of white light.
One of the problems with human understanding of color in space is that the human eye can only see certain colors. In space, the color of an object will depend upon its own temperature and chemical composition.
Stars emit light across the entire spectrum, from ultraviolet to infrared, meaning that different colors correspond to different wavelengths of light.
A star’s color is determined by its surface temperature, with hotter stars appearing blue, and coolest stars appearing red.
To a lesser extent, the color of a specific star also depends on its chemical composition. Different elements absorb and emit light at certain wavelengths, creating what we call ‘spectral lines,’ that can be used to identify the elements present in a star. As an example, carbon stars are orange to cinnabar red in color.
Hydrogen, for example, will absorb and emit light at specific wavelengths in the ultraviolet and visible parts of the spectrum, creating a characteristically pinkish-red color.
It’s worth noting that other celestial bodies can also have distinct colors. For example, dust or gas clouds in space often appear as red or pink due to the presence of ionized hydrogen.
Planets and moons can also have a range of different colors due to their surface composition and atmospheric conditions. Our nearby planet Mars appears a rusty shade of red from our vantage point on earth.
Polaris is Moving
While Polaris may appear to be permanently stationed over the north pole this will not always be the case. Because the Earth’s axis ‘wobbles’ Polaris moves around about our axis of rotation. In about one thousand year’s time, Polaris will have moved so far that the star called Gamma Cephei will be the North Star.
At the current time Polaris is 0.7 degrees from the North Celestial Pole.
Final Thoughts
So to conclude our article on the color of Polaris, you should know that it appears white to the naked eye, but that’s not the end of this story. Polaris is actually a complex system of three distinct stars.
The primary star, Polaris A is a yellow supergiant. Blending the light from the three stars creates the perception of white light to us on planet earth.
We hope this article has helped you understand the color of stars and other astronomical objects.
The color of these celestial bodies is important for astronomers, as it provides information about the temperature and chemical composition of these objects.
Since these objects are so far away from us, researchers need all the information they can get! If you still have some questions, check out our FAQ below.
Frequently Asked Questions
Can The Color Of A Star Change?
The color of a star can change over time as it ages and evolves. It’s worth stating that all stars are far from us, and we see light from a long time ago.
How a star looks at this exact moment in time might not be what we perceive. As a star exhausts its fuel, it may contract or heat up, causing it to appear blue.
Alternatively, a star that is running out of fuel could expand and cool down, causing it to appear redder to use.
Are All Stars White?
No, we know that stars can appear in a range of colors depending on their chemical composition or temperature. A general rule to follow is that hotter stars will usually appear blue, and cooler stars will appear more red.
Yellow stars, like Polaris A, are what we would call intermediate in temperature.
Do Other Stars Appear Stationary In The Sky?
There are other stars, for example, Gamma Cephei that appear relatively stationary in the night sky. Polaris is the most recognizable by humans, however.
Hi, my name is Jason Anderson, and I am a Physics Professor. Ever since I was a kid, I’ve been fascinated with space, the universe, the moon, you name it. I spent hours and hours at the planetarium close to my hometown, wondering what else could be out in the universe.
Since then, I’ve been an avid stargazer and astronomer, and love nothing more than spending my time charting stars, observing planets, and finding constellations.
This is why I decided to start Telescope Guru. I only wish to share this fun pastime with the world. With this site, I hope to answer all of your questions relating to astronomy, telescopes, and stargazing.
