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A day on Mars

Space and time · level 1, lesson 5 of 6

A question to start

Mars spins round too, so it has days and nights. Is a day on Mars the same length as a day on Earth?

The idea

Almost. Mars spins a little more slowly than Earth. From one sunrise to the next takes about 24 hours and 40 minutes: about 40 minutes longer than a day on Earth.

A day on Mars has its own name: a sol.

A day Mars Earth
Name a sol a day
Length about 24 hours 40 minutes 24 hours

The people who drive rovers on Mars sometimes live on Mars time. Each day they start work 40 minutes later than the day before.

24 hours24 hoursEarth: a dayMars: a sol, plus 40 minutes

Worked examples

1. A little longer. A sol is about 40 minutes longer than an Earth day.

2. Two sols. After two sols, Mars time is about 80 minutes, nearly an hour and a half, behind Earth time.

3. Starting late. A rover team on Mars time that starts at 8 o'clock today starts at about 8:40 tomorrow.

Try it

  1. What is a day on Mars called?
  2. Is a sol longer or shorter than an Earth day?
  3. By about how much?
  4. Why do some rover teams start work later each day?
Answers
  1. A sol.
  2. Longer.
  3. About 40 minutes.
  4. They are living on Mars time, and each sol is about 40 minutes longer than an Earth day.

Common mistake

"Every planet has a 24-hour day." Each planet spins at its own speed. Mars's day is close to ours, but Jupiter's is under 10 hours.

Where it leads