Page 100 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

What colour

are the planets?

Discover the science behind the colours in our Solar System
Planetary
f the eight planets in our Solar System, only two The colour of each planet is determined by what they colour palette
can’t be seen unaided from Earth – Uranus and made up of, and in some instances, how their
O Neptune. And even then, unless you’re atmospheres absorb and reflect light from the Sun. Here’s how each planet is

coloured, with each colour
observing through a telescope, the physical The four terrestrial planets, which have solid rock indicative of a certain element
appearance of almost all planets will be diffi cult to surfaces, are mostly grey or reddish-brown in
perceive. Except of course Earth’s neighbouring planet, appearance due to elements such as iron found on the Q Hydrogen (H )
Mars, which even ancient cultures correctly surface. However, the surface of Venus is diffi cult to 2
documented as being red, as its orange-red glow is detect from space, as a dense atmosphere and thick Q Carbon dioxide (CO )
2
distinguishable from Earth. clouds of acid surround it. The sulphur present in the Q Helium (He)
Space missions and scientific advancements in the clouds reflects the light and gives Venus its noticeable Q Nitrogen (N )

2
last century have greatly improved our perception of yellow colouring. A similar principle applies when it Q Oxygen (O )
2
the planets, including those closest and farthest away comes to determining the colours of the four gas giants. Q Methane (CH )
4

from the Sun. As a result we are now finally able to Uranus and Neptune, for example, appear to us as blue Q Sodium (Na)
identify a planet’s true colour and – more importantly because methane gas present in their atmospheres Q Argon (Ar)
– understand why it appears as such. absorbs red light, enabling them to only refl ect blue. Q Other gases (Oth)

1% CH 1% Oth
4
3% 3%
He
CH
4
19% He 15% He

Saturn
Neptune 80% H 82% H The lightest but 96% H
Smallest of the 2 2 second-largest 2
four gas giants, Uranus planet in the Solar
Neptune shares a Although System. This gas

lot of physical classified as a gas giant is mostly made
similarities with its giant, an icy layer of up of hydrogen and
neighbour Uranus, cloud covers the planet helium, but traces of
including its blue colouring. It’s Uranus. The coldest planet in ammonia, phosphine, water
considered the windiest planet, with our Solar System, temperatures at vapour and hydrocarbons in its atmosphere
speeds recorded at around 2,414km/h cloud level drop to below -220°C (-364°F). give the planet its distinct yellowish-brown
(1,500mph). Extreme storms are also Methane in its atmosphere gives colour. Saturn’s famous rings, which are
known to occur in its atmosphere and Uranus its distinct turquoise primarily made up of water ice, share a similar
the planet also features a giant storm appearance; as red light is absorbed, hue, but also vary in colour depending on
spot like Jupiter. only green-blue light is refl ected. density and the presence of other materials.

100
100 How It Works
How It W

orks