(MUSIC)

Joan Cartan-Hansen, Host: We
measure a day by how long it

takes for the Earth to turn
once on its axis, and a year

by how long it takes the Earth
to revolve around the Sun.

A day on Earth is about 24
hours and a year is about 365

days.

But how long is a day or a
year on the other planets in

our solar system?

A day on Mercury lasts 1,407
Earth hours but a year is only

88 Earth days.

That's because Mercury rotates
slowly on its axis but

revolves quickly around the
Sun because it is so close to

the Sun.

A day on Mars is only 37
minutes longer than a day on

Earth.

But a year on Mars is much
longer at 687 Earth days.

A day on Jupiter is the
shortest in the solar system

at only 10 hours.

And a year on Neptune is the
longest at 60,190 earth days.

So, the length of a day
depends upon where you are in

the solar system.

For more information about the
planets, check out the Science

Trek website.

You'll find it at Science Trek
dot org.