Pendulum and gravity?

[spherimorph]

How does one go about measuring gravity using a pendulum on other planets? I don't quite understand how and why this works...

[jtbell]

Hint: the period (time for one cycle) of a pendulum with length L is

T = 2 \pi \sqrt{\frac{L}{g}}

See for example

http://hyperphysics.phy-astr.gsu.edu/hbase/pend.html