Stars

Did you know that a star colour is directly linked to it's temperature? When looking at a color spectrum (from purple to red) you can apply the temperature, the highest the temperature the more blue the star the lowest the more red, there is a category of stars called white star, it's between yellow and blue, because apparently physics don't want green stars floating around, how sad. The temperature is in Kelvin (noted K, we'll come back to that at the end)

Let's start with the most known to mankind star, the Sun. With a temperature around 6000K, tend to the blue part of the spectrum, it's actually a pure white star. So then why is it yellowish from Earth and in documentary? Well because if we show you the Sun white you will not recognize it so documentary images are filtered to appear more yellow (when it's not entirely a artist rendition). The sun look yellow from Earth for the same reason that the sky is blue and what is this reason? Well, the gaz the atmosphere is made of will act as a filter to the sun light, it will absorb the blue light from it making the sky blue and the counter color of blue being yellow the sun will appear yellow. (Obviously since the sun don't shine at night the atmosphere don't absorb light and become transparent again, making us able to see the stars).

Another star, to show another example. Betelgeuse. Betelgeuse has a temperature around 3500K, making it red-orange. If you can see the Orion's constellation you will be able to see Betelgeuse since it will appear red-orange, wich is quite unusual to the night sky, we don't really see the different colors. Betelgeuse is also really interesting for other reasons, but that have little to no link to what we are talking about right now.

On an ending note we will talk about Kelvin, the temperature measurement used above. It's easy to calculate the Kelvin value of a temperature, you take the temperature in Celsius and had 273.15. See : 26°C + 273.15 = 299.15 K. Don't ask about fahrneight, I don't even understand why it exists. (I'll make an addendum in the comments don't worry). Kelvin is used to calculate extreme temperature, precisely those you come across in space.

Tell me in the comments what you want to learn about next time. :D