A recent discussion on the internet suggests that people believe the Sun has changed color over the past few decades. Some shocked Twitter users claimed in a thread that people believed the Sun used to be yellow and now white.
“I tell someone in his 20s that the sun was yellow when I was a kid and he laughs,” wrote one Twitter user: “He says he last saw a yellow sun on Teletubbies. Here is the sun right now. It is white and has a strange shape. How does it look where you are?”
In fact, this idea is not new and has been the subject of conspiracy theories for years.
Has the color of the sun changed over the years?
Writer and filmmaker Jay Weidner said in 2017, “The sun used to be yellow. Is it ok? The sun is no longer yellow. Now it’s white,” he said.
So what color is the Sun really? As former NASA astronaut Scott Kelly confirmed, if you look at the Sun from above the atmosphere, it looks white.
This is because the Sun emits light that includes all wavelengths, including all colors in the visible spectrum, and we perceive light that contains all colors as white. However, when the Sun hits our atmosphere, light in the blue spectrum is scattered more efficiently than red light. Therefore, we perceive the Sun as slightly yellow, since less of the blue part of the white light reaches our pupils. For example, at times when light has to pass through more of the atmosphere, such as at sunrise and sunset, blue light is scattered more, causing the sun to appear more yellow or red.
Similarly, because less of the light has to pass through the atmosphere when the Sun is directly above you, relatively less of the blue part of the light will be scattered and the light will appear whiter.
The belief that the Sun is yellower as a child may be due to nostalgia, a tendency to remember a beautiful sunset over a normal day, or, as one Twitter user suggested, due to higher air pollution when young.
Moreover, knowledgeable people might argue that our Sun is green for fun, just to really stir things up.
As NASA explained before the 2017 eclipse, “Actually, the sun emits energy at all wavelengths, from radio to gamma rays. However, it emits most of its energy around 500 nm, which is close to blue-green light. So it can be said that the Sun is a blue-green color!”
However, because the Sun emits all wavelengths, not just blue-green, we still see it as white when this spectrum hits our pupils.
The result is this: You can be sure that the Sun has not lost its yellow color over the years…
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