Question: How do you know what colour a planet is?

Lucy Kissick answered on 10 Mar 2017:

This is a really great question because when it comes to objects like Pluto you can’t count on sunlight to see by. For Pluto, two different cameras used different wavelengths of light to colour their images the way human eyes would see it in real life. A lot of the time the known colour of chemicals are used to interpret colours: for instance with Neptune, if you know what the atmosphere is made of (mostly methane) and its temperature, you can figure out what the colour should look like (blue) and compare that with you camera’s data. A lot of images of planets are confusingly enhanced to show variations or just to look pretty, and to make matters worse some spacecraft cameras can’t detect wavelengths that the human eye can. So it’s all a bit iffy!

Here’s a great article I found by astronomers at Cornell University, USA, about the approximate true colours of each planet: http://curious.astro.cornell.edu/about-us/58-our-solar-system/planets-and-dwarf-planets/planet-watching/249-what-color-is-each-planet-intermediate