Last month, director of the Manfred Olson Planetarium at UW-Milwaukee and our regular astronomy contributor, Jean Creighton explained how the sun stays together, even though it is made of gasses and plasma.
This month, Lake Effect’s Bonnie North wanted to take the conversation one step further, and talk about the same issue, only this time as it pertains to planets and their atmospheres.
Creighton notes that while gravity does play a key role in maintaining atmospheres, there are different planets and moons that don't even maintain an atmosphere - depending on their size and mass. Basically, the more mass a planet has, the stronger the pull of gravity, says Creighton. However, she explains that your speed depends on the mass' temperature.
"If I’m really close to the sun, for example, it stands to reason that I’m going to be hot, and that molecule is going to be moving really fast," she says. "So gravity, over a long period of time, is not going to be able to hold onto me."
Creighton dives into escape velocity and how it relates to black holes: