Colours of the planets of our solar system are determined by the way their surfaces reflect sunlight.
This may vary a lot due to the composition of the atmosphere, a rocky surface, or a lack of a rocky surface.
In this article, you will see a lot of similarities in the structures of Terrestrial(Rocky) and Jovian(Gaseous) planets. Mercury, Venus, Mars, and Earth are rocky planets. Therefore their colors are mostly determined by the materials on the solid surface.
Colours of gas giants are determined by the composition of their atmospheres. These planets are Jupiter, Saturn, Uranus, and Neptune.
Digital Solar System Colour Scheme
Mercury, Mars, Venus, Earth, Uranus, Neptune, Saturn, Jupiter, The Sun
The colour of the Moon is light gray.
The Moon, NASA
Why does the Moon change colours?
Red and colours closer to red in the light spectrum travel easier in the atmosphere. So when the Moon is lower in the sky, it will have a reddish colour. As it rises up in the sky and the atmosphere between the Moon and you is lesser, most colours of the Moon are able to pass the atmosphere. When the Moon is right above you, it will show its true colour, which is light gray.
Different Colours of the Moon
Why is the Moon gray?
The surface of the Moon is mostly metallic. Magnesium, iron, calcium, and aluminum are common on the Lunar surface, which are gray metals.
Mercury is also gray. Many illustrations depict Mercury as a brown-yellow planet, which is simply not true.
Mercury is very similar to the Moon in terms of composition. Its surface is mostly Silicon, Aluminum, Calcium, and Magnesium. As we’ve mentioned before, these are all gray materials.
The Colour of Venus depends on where you are looking. If you were at the surface of Venus, it would look brown-reddish. If you were outside the planet, it would look yellow.
Venus, NASA – Venus’ Surface, Venera-13
Why does Venus look yellow?
The colour difference is due to Venus’ thick sulfur dioxide atmosphere. The atmosphere is so dense that the real surface colour of Venus is not visible. In fact, if you were standing on the surface of Venus, you wouldn’t see anything at all since sunlight can’t pass through the atmosphere.
Our home is a pale blue.
Because of the oceans. Although water looks transparent, it is actually blue. It won’t show in a glass of water, but in an ocean, it will show.
If you are curious, the reason water is blue is that it absorbs red light easily. The only thing left to transmit colour is blue light.
The “red planet” is, as you might guess, mostly red.
Mars, NASA – Curiosity’s View of Mars
The surface of Mars is mostly Iron(III)-Oxide. This molecule has a strong red colour. Adding to that, the atmosphere of Mars is fairly thin, which allows us to see the true colour of the surface.
Jupiter has different shades of white, red, brown, yellow, and orange.
Jupiter is mostly gas. The atmosphere is mostly Hydrogen and Helium, which are completely transparent.
The colour of the surface is defined by materials that are brought to the surface from the core by powerful storms. These materials are Phosphorus, Sulfur, and Ammonia crystals.
You can see this clearly on the Great Red Spot. The huge amounts of Phosphorus give the storm a reddish colour.
Saturn is mostly pale yellow mixed with orange and brown.
Saturn is very similar to Jupiter but without the crazy storms. The atmosphere of Saturn consists of Hydrogen and Helium, which are completely transparent.
The colour is given by ammonia crystals on the surface, the same as Jupiter.
Uranus is pale blue.
Uranus, like Saturn and Jupiter, is mostly Hydrogen and Helium. Since these materials are completely transparent, the colour is due to another material.
The blue colour is given by methane, the third most common material in the atmosphere.
Neptune has a strong blue colour. That is why Neptune corresponds to Poseidon in Greek Mythology, god of the seas.
The case of Neptune is exactly the same as Uranus. High levels of methane in the atmosphere give it a blue colour. The reason it has a stronger blue than Uranus is that Methane levels are higher in Neptune’s atmosphere.
The surface of Pluto is a mix of red, brown, light gray, yellow, and white. All these colour have a strong presence on the surface.
Pluto’s surface is mostly composed of organic materials such a carbon dioxide, methane, and ethane. Due to the thin atmosphere, these materials are exposed to high levels of radiation coming from the Sun. The resulting organic, brown, sticky material is called “Tholin”, a name given by astronomer Carl Sagan.