elemental abundance
"I have this one little saying, when things get too heavy just call me helium, the lightest known gas to man." -Jimi Hendrix
Hendrix, as I told you once before, was almost right. We know of helium, conventionally, as the lighter-than-air gas that we fill balloons, blimps and zeppelins with in order to quickly and easily "defy gravity" here on Earth.
Image credit: Jonathan Trappe.
At least defying gravity is what it appears to do. But what's really going on is that helium is simply a very low-density gas. Our atmosphere, a mix of mostly Nitrogen (N2) and Oxygen (O2) gases, has an average…