Monday, 10 April 2017

H is for Hydrogen and Helium

H is for Hydrogen and Helium, pretty much most of the matter of the universe.

For an astronomer, the Periodic Table of the elements goes like this: hydrogen,  helium, everything else.  (Okay, it really goes, hydrogen, helium, 'metal', starkiller (iron), supernova poop.)

Hydrogen is the most abundant element in the Universe at a whopping 74% of all baryonic matter. Helium takes up about 24%, which leaves about 2% for everything else. Most of that hydrogen and helium float about as Interstellar Medium (ISM), gas clouds like nebulae and gravitationally collapsed into stars.

Why's this? Because in the early seconds of the Big Bang, hydrogen was the easiest atom to synthesis through Big Bang nucleosynthesis. Helium wasn't too hard to synthesise either. Heavier elements tend to be nucleosynthesised in stars through fusion or by supernovae. (This is why they tend to be called "metals" by astronomers, regardless of what they are. If you're not hydrogen or helium, you're a metal.)

A hydrogen atom: one proton, one electron.
Doesn't get any more basic than that. 
How do we know there's so much hydrogen out there? Because hydrogen has its own little radio broadcast channel along the 21cm wavelength line or 1,420 MHz. (Okay, it's more in the range of microwaves, than actual radio waves, but still cool to a radio astronomer.)

In fact, once we were able to identify hydrogen, we were able to see so much more of the Universe, as microwaves at that 21cm frequency can easily penetrate the clouds of dust that tend to block visible light. It was by mapping the hydrogen of the Milky Way that led us to discover it was a spiral galaxy.

Hydrogen hardcore: observing the universe through 21cm.

Do you think we'll run out of hydrogen eventually? How?

____________________________
Her Grace once used hydrogen to fill up party balloons because she'd run out of helium.

7 comments:

Shawna Atteberry said...

I had no idea hydrogen and helium made up so much of the universe. It's cool by mapping hydrogen we discovered the Milky Way was a spiral galaxy.

Emily Bloomquist said...

When I was young and heard of a radio astronomer, I thought they were listening for messages from other life forms. I figured it would be terribly boring until a message arrived, then pandemonium.

Thanks for the informative post.

Emily | AtoZ | My Life In Ecuador

DeeDee said...

I knew this, but it was nice reading it all over again
I felt like I was in my Chemistry class again :-)

A Peice Of My Life

Sarah Zama said...

Well, I'm completely inept in terms of physics, but I do understnad what you say :-)
Great post. You managed to make comprehensible somethign that is really quite complex, I think.

@JazzFeathers
The Old Shelter - 1940s Film Noir

Sandra Williamson said...


Why didn't I discover your blog earlier? Now I've got a lot of catch-up reading to do. Love your content.

Dropping by from the A to Z Challenge

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Sandra, Aspiring family historian, fellow participant in the #AtoZchallenge

Sandra's Ancestral Research Journal

sage said...

You make radio astronomy sound exciting--I always thought it rather dull, like listening in to 1930 radio programs and unable to respond. Great post!

A Tarkabarka Hölgy said...

Fascinating! :)
Also, supernova poop? That sounds like one of my topics... :D

The Multicolored Diary: WTF - Weird Things in Folktales