Facts about Earth and the universe

Why Is the Sun Yellow?

 
Matthew Nesbitt
By Matthew Nesbitt, Writer and researcher. December 6, 2022
Why Is the Sun Yellow?

We tend to think of stars and the sun as being different, but they are actually the same type of object. The main difference between them is their distance from the earth. The sun is a star like any other in form and function, but our sun is special because it allows us to have life on this planet. Without the light and heat our sun provides, Earth would be a very different place. Due to the sun's heat and light, we often think of it as a fire. Looking up to the sky, we can see often see the sun as a yellow ball emanating its rays. Some of us may wonder why this is so.

At thedailyECO, we find out more by asking why is the sun yellow? The truth is, it isn't. The sun is not actually yellow. Find out more as we explain the coloration of the sun.

You may also be interested in: What Are the Layers of the Sun?

Contents

  1. What color are the stars?
  2. Why are stars different colors to the sun?
  3. Why is fire red or orange?
  4. Why is the sunset sky red?

What color are the stars?

When we see the sun during the daytime, it is yellow. When we see stars at night time, they are bright white lights. At least, this is how they apear to our human eye. Stars are so far away, it is not only hard for us to see the, it is hard for us to comprehend the distance.

We can see a certain amount of stars depending on the weather and where we are in the world, but this is not a fraction of their total amount. According to the National Radio Astronomy Observatory, the naked eye can only see about 0.0000045% of all the stars in our galaxy[1]. This is nothing compared to the amount of stars present in the entire universe, a number we are likely never to know.

In reality, stars are not all white. In fact, they can be of a wide variety of colors across the spectrum. Stars can range from red to blue to orange and even to green. Despite their range in color, the light which reaches us is on similar wavelengths.

The reason stars are of varying colors is mainly due to temperature differences on their surfaces. The coolest stars (around 3,000 K temperature) have a reddish color. The hottest temperature stars (around 40,000 K) have a bluish appearance. In between, we find a range of temperatures that determine the color of stars, the most common being those in the near range of temperatures around 5,000 or 6,000 K, which have a yellowish hue.

Why are stars different colors to the sun?

As we have seen, the color of stars is determined by the temperature of their surface. By this reasoning, the color of the sun will also be dependent on its temperature. The sun is the star closest to the earth and its temperature is around 6,000 K. For this reason, the sun is white in color. This is because it emits all the colors of the visible light spectrum. When these colors are perceived together, they appear as a bright white.

Although the sun is actually white, this does not explain why we see it as being yellow. The reason for this has to do with our Earth's atmosphere.

Unless we observe the sun through a microscope, we see various tones such as yellow, orange and even red. The Earth's atmosphere has a high oxygen concentration. This facilitates our ability to breathe, among other things. Before the light of the sun can reach the surface of the earth, it has to pass through this atmosphere. This oxygen-rich atmosphere acts as a filter and removes some of the colors from the light spectrum. It is for this reason we only see certain colors, such as yellowish or orange tones.

Why is fire red or orange?

If we take the example of a fire in a fireplace, we can see that various colors are emitted at different times. Sometimes there is a blue flame at the bottom, other times we can only see red and yellow flames licking up the coals. These colors are present depending on the different temperatures of the fire. We can see them thanks to our proximity to the fire.

As stated above, stars are also of varying temperatures. They are also much further away from us than any fireplace on the earth. If we see a series of fires from miles away, we cannot discern the blue flames and variations in color. They will all seem to be the same color. Although the Earth's atmosphere will also filter the colors of stars, their great distance away means they all look the same color to us.

The sun appears as a different color to other stars simply because it is closer to us. We have a greater ability to see the variances in color and the filtering process acts differently.

Why Is the Sun Yellow? - Why is fire red or orange?

Why is the sunset sky red?

Although sunsets can present in various colors, it is common to see it become a beautiful brilliant crimson red when it is low in the sky. We cannot always see this due to our geographical location and the amount of cloud coverage, among other factors.

The reason a sunset sky is red, orange or a range of colors is also to do with the earth's atmosphere. As the earth orbits around the sun, the distances between the two objects vary. When the sun is setting, the light from the sun travels a much longer distance so it needs to travel through more atmosphere.

Different colors has different wavelengths. Blues, greens and other colors emitted by the sun are diffused to a greater extent, meaning they get lost in the visible spectrum. This is a process known as Rayleigh scattering. Essentially a light filtration process, the reds and other colors are not diffused as much due to their longer wavelengths. The result is a sunset sky which appears red, orange or similar. It is for the same reason the sky appears blue during the day since the blue light from the sun is less scattered.

Learn more about the importance of our sun for life on earth with our article on types of chlorophyll and their function.

If you want to read similar articles to Why Is the Sun Yellow?, we recommend you visit our Facts about Earth and the universe category.

References

1. Mangum, J. (2020). What Percent of the Visible Objects Seen in the Night Sky with the Unaided Eye are Beyond our Galaxy and Solar System? Retrieved from:
https://public.nrao.edu/ask/what-percent-of-the-visible-objects-seen-in-the-night-sky-with-the-unaided-eye-are-beyond-our-galaxy-and-solar-system/

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