Skip to content

Sunlight on Mars

Waves, sound and light · level 2, lesson 6 of 6

A question to start

If you stood on Mars at midday, the Sun would look smaller and the light dimmer than at home. How different would it be?

The idea

Mars is about one and a half times as far from the Sun as Earth is. Two things change:

  • The Sun looks smaller: about two thirds as wide as it looks from Earth.
  • The sunlight is dimmer: each square metre gets less than half as much.

It is still bright enough to see well, to cast clear shadows and to power solar panels.

from Earthfrom Mars
Sunlight Mars Earth
Distance from the Sun about 228 million km about 150 million km
How wide the Sun looks about two thirds full size
Sunlight on each square metre 586 watts 1,361 watts

Worked examples

1. How many times as far? \(228 \div 150\) is about 1.5.

2. How much light? 586 out of 1,361 is a bit less than half.

3. Shadows. Mars still has a single bright Sun, so shadows there are still sharp and clear.

Try it

  1. Why does the Sun look smaller from Mars?
  2. Does Mars get more or less sunlight than Earth?
  3. About how much smaller does the Sun look from Mars?
  4. Are there shadows on Mars?
Answers
  1. Mars is further from the Sun.
  2. Less: a bit less than half.
  3. About two thirds as wide.
  4. Yes, clear ones.

Common mistake

"Mars is dark." The sunlight is less than half as strong, but that is still far brighter than a well-lit room. Mars's days are bright.

Where it leads