Physics trivia

color of the Sun

Despite being represented as an orange, yellow and even red star, none of these colors are really what the sun presents.

Despite being represented in orange or reddish tones, the Sun has another color originally
What is the color of the Sun?

It is common to see the Sun represented in orange or even in shades close to red . However, like all other stars, the Sun produces its own light through the process of nuclear fusion . During these intense reactions, all wavelengths of the electromagnetic spectrum are produced, from infrared to gamma rays , passing through all wavelengths of visible light , from violet to red (between 380 nm and 720 nm). Therefore, the Sun is white.

The shades of yellow and red that we see when looking at the Sun arise because of the dispersion of solar rays as they enter the atmosphere. Look at the photo below:

Why do we see the Sun in shades of orange and red?

When light produced by the Sun hits the Earth’s atmosphere , some smaller wavelengths, such as violet and blue, are immediately scattered by the small particles that make up the atmosphere. This phenomenon is called Rayleigh scattering and only occurs in cases where the illuminated particles are much smaller than the wavelength of the incident light, and is therefore a much more frequent phenomenon in gases .

In this way, longer wavelengths, such as orange and red , are able to pass through the atmosphere without suffering a large scattering , so the sky has a blue color , and our light source, the Sun, has an orange or orange tone . red .

Why, then, do we see the sky blue and not violet ? The answer lies in light sensitivity . Cells specialized in capturing colors, called cones , respond better to light stimulus whose wavelength is between green and blue (about 508 nm) than to ultraviolet, so these tones are more visible to we.

solar spectrum

The Sun is categorized as a main sequence star , meaning it fuses Hydrogen atoms into Helium atoms to produce its energy. Within this astronomical classification, the Sun is considered a yellow dwarf star. Its category, however, does not have to do with its color, but with its diameter and the temperature of its surface , of approximately 5800 K.

In addition, although solar radiation has all visible wavelengths, the Sun does not produce them with the same intensity, that is, some frequencies are produced with greater power by the Sun. Among the visible colors, the blue region is the most produced by the sun, for example.

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