# Why does the Earth still have helium? **URL:** \ **Category:** Factual Questions\ **Created:** [June 21, 2006, 3:35am UTC](https://boards.straightdope.com/t/why-does-the-earth-still-have-helium/361536 "2006-06-21T03:35:26Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![purpler](https://avatars.discourse-cdn.com/v4/letter/p/cab0a1/32.png) [@purpler](https://boards.straightdope.com/u/purpler)\ **Post date:** [June 21, 2006, 3:35am UTC](https://boards.straightdope.com/t/why-does-the-earth-still-have-helium/361536/1 "2006-06-21T03:35:26Z")
It’s lighter than air, chemically inert (for the most part), and the Earth has been around for 4.7 billion years. In all that time, why hasn’t all the helium bubbled out and away to the upper stratosphere? ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [June 21, 2006, 3:40am UTC](https://boards.straightdope.com/t/why-does-the-earth-still-have-helium/361536/2 "2006-06-21T03:40:06Z")
New helium is being made through radioactive decay, and some of this gets trapped in helium-tight spaces underground. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [June 21, 2006, 3:46am UTC](https://boards.straightdope.com/t/why-does-the-earth-still-have-helium/361536/3 "2006-06-21T03:46:45Z")
[Helium](http://education.jlab.org/itselemental/ele002.html) > [@](#): > > Helium makes up about 0.0005% of the earth’s atmosphere. This trace amount of helium is not gravitationally bound to the earth and is constantly lost to space. The earth’s atmospheric helium is replaced by the decay of radioactive elements in the earth’s crust. Alpha decay, one type of radioactive decay, produces particles called alpha particles. An alpha particle can become a helium atom once it captures two electrons from its surroundings. This newly formed helium can eventually work its way to the atmosphere through cracks in the crust. Just in case you’re asking this because creationists use the presence of atmospheric helium to argue for a young earth, see [Radiometric Dating from The Evolution Evidence Page](http://www.gate.net/~rwms/AgeEarth.html) ---
**Author:** ![PBear42](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@PBear42](https://boards.straightdope.com/u/PBear42)\ **Post date:** [June 21, 2006, 3:49am UTC](https://boards.straightdope.com/t/why-does-the-earth-still-have-helium/361536/4 "2006-06-21T03:49:33Z")
Wikipedia can be your friend: [Helium](http://en.wikipedia.org/wiki/Helium). ---
**Author:** ![purpler](https://avatars.discourse-cdn.com/v4/letter/p/cab0a1/32.png) [@purpler](https://boards.straightdope.com/u/purpler)\ **Post date:** [June 21, 2006, 6:07am UTC](https://boards.straightdope.com/t/why-does-the-earth-still-have-helium/361536/5 "2006-06-21T06:07:37Z")
[QUOTE=Exapno Mapcase] Just in case you’re asking this because creationists use the presence of atmospheric helium to argue for a young earth, see … [/QUOTE] Thanks for that info! I realize you don’t know me, because i’ve been mostly lurking on these boards for years and not posting much (i read them voraciously, though), but i got quite a good laugh out of your mild insinuation that i might be a YEC. I do have three of them in my family, though, and it does make Thanksgiving conversation rather…strained. **PBear** : i did check Wikipedia right before asking, but somehow i missed the paragraph about radioactive decay. I’ll read more thoroughly next time. 🙂