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“People have talked about water worlds and thick hydrosphere planets off and on for 20 years,” says Jonathan Fortney, an astronomer at the University of California, Santa Cruz, who was not involved in the work.

First, the atmosphere, hydrosphere, geosphere and biosphere are linked.

Audience members watch as Sagan encounters eccentric characters representing the atmosphere and the hydrosphere, as well as a man trying to find a way to escape the planet through space travel.

“They don’t take it that we have a problem with the hydrosphere. They don’t really connect what happens on the Mont Blanc glacier and what happens in the Mediterranean Sea.”

Their curriculum this semester focuses on the hydrosphere, but she has moderated her message for students shell shocked by their narrow escape.