hypsometry

Hypsometry of the Planets

We all have ups and downs.

Consider a plot of the fraction of a planets surface at each altitude. (Of course what I really mean is the fraction within each altitude interval, say within a 100 m wide interval centered on 0 elevation, i.e. "sea level" on earth.)

For Earth, Mars and the Moon such a graph shows two peaks.

On Earth we see one peak for the Ocean floors and one for continents.
On Mars we see one peak for ancient cratered terrain and one broad peak for the northern highlands.
For the moon we see one peak for mare and another for highlands.

For Venus there is only one peak, and for Mercury the data is too sparse to plot..

One great question is, why is Venus so different?

Another way to plot this data is to plot the intergral of the data. That is to plot the total fraction of a planet beneath a given altitude. This leads to a representative image of the surface of the planet.

For the earth notice the two levels representing the ocean basins and continents plus the deep ocean trenches and the mounains.

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