"...how fast something must be going to escape the gravity of another body completely. Something thrown directly away from a body at escape velocity would never fall back. This value is important for more than just space travel! It's also one of the parameters that determines whether a planet can keep an atmosphere."
where r is the radius of the planet, M its mass, p (Greek letter rho) its mean density, and G the gravitational constant. The escape velocity from earth is 11.2 km/s or 25,000mph.
You might remember me talking about casimir forces and exotic matter, things I learned about while researching wormholes for my new project. The above definition of escape velocity comes courtesy of World Building by Stephen L. Gillett. It's an older book - 1996 - but it still has some pretty good information, like the fact that gravity forces planets (and suns) into spheres. Did you know that?
You can track my progress with my new work - tentatively titled NO REST - on my sidebar where I've added a widget.
What are you working on? Learned anything interesting lately?