If helium is the second most abundant element in the universe, why is there very littleon earth?
Just our of curiosity, why isn’t your question about hydrogen? After all it is the most abundant element in the universe, so why isn’t it also the most abundant on our planet? Apply whatever answer you get to the same question about helium.
I suspect that, if helium was present in large quantities in our atmosphere, we wouldn’t be discussing it now- at least not in our present forms. We’d be some different product of evolution, hovering in front of our computers & wondering where all the hydrogen is.
It’s all just a matter (har!) of distribution, if I may oversimplify a bit. Since stars are mainly hydrogen, and slowly convert that hydrogen to helium, it follows that a huge portion of the hydrogen in the universe (and therefore also the helium) is found in the stars.
Gas giants could have been stars, they just weren’t massive enough. I think I remember Carl Sagan once described Jupiter as “a star that failed” because it lacked the necessary mass to collapse on itself & begin the process of nuclear fusion.
Because helium molecules are too light to be easily held by Earth’s gravity and so wind up escaping into space. Hydrogen is lightweight too, but it readily bonds with other heavier elements (like oxygen) and so tends to stick around.
From Web Elements - Helium:
As mentioned by others, Hydrogen, although lighter than Helium in its gaseous form, readily reacts with other elements to form heavier molecules that Earth can hold on to. Helium is a noble gas however, so it tends to keep to itself and float off into space.
Wow nobody’s answered this yet. I’m sure the experts are at lunch and will get here soon. Meanwhile stuyguy, science buff that he is, will give it a crack.
Being very, very light, most of earth’s atmospheric Helium dissipated out of atmostphere and off into space when the planet was being formed. Helium is very, very stable all by it’s lonesome – meaning it’s very nonreactive and does not combine with other elements (and get “trapped” in earthbound compounds) like Hydrogen does.
So how do we “get” helium to put in blimps and kiddie balloons? Because it is a byproduct of the radioactive decay of underground radioactive minerals, there are gobs (sorry, I couldn’t think of a better word) of the stuff collecting in pockets of natural gas. That’s we we get our Helium – it’s “filtered” out of natural gas.
Am I right, geeksters?
Damn. See I told you they’d get here!
(PS - In my post, “we we” = “where we.” Sorry.)
Agreed, collected from pockets. Read it in one of those Big-Bang-Explained books that were popular in the eighties. The real question is, where is all the antimatter? 
The USA is the world’s largest producer of helium. It’s a byproduct of natural gas wells. The helium industry is centered around Amarillo, TX.
This has been another Useless Fact.