This poses an interesting question: How do you measure altitude on other planets, such as Mars, when there is no sea level.
The Science Report
by Stuart Gary
How do you measure height on Mars?
I’ve just written a story for ABC Science about measuring altitude on other worlds.
On Earth, mean sea level is used as the reference point for measuring elevation.
But what do you do on other worlds which have no sea level?
It turns out zero altitude on Mars, is defined as a specific atmospheric pressure of 610.5 Pascals, about six millibars, which is the triple point of water on the red planet, where it can exist as gas, liquid or solid.
As for the Moon, which has no significant atmosphere as well as no oceans, the zero elevation point is the average diameter.
If you missed my radio report on the story and you want to find out more, check out the online version at: