What are Stars completely made of?

Hi Breanna,
Stars and sun are the same... so here's the data on the sun:
Mostly about 2/3 hydrogen and 1/3 helium with a trace amount of most of the other elements.
But this is NOT your normal hydrogen and helium gas we see on the Earth at 1 atmosphere pressure and 72 degrees F.
It's highly compressed (due to the high gravity) and very very hot, like millions of degrees hot!  It's so compressed and hot in fact, it acts more like a liquid than a gas... we call it a plasma.  It's so hot that all the electrons have scurried away, so all that's left are the bare nuclei of hydrogen and helium down in the core, so they really aren't even "atoms" of hydrogen and helium, they are ions.  (An ion is an element that's lost one or more electrons).
The central core is so hot and compressed that hydrogen fusion reactions take place, fusing 4 bare hydrogen protons to form one nuclei of helium and release of tremendous amounts of energy.
(We do the same for an instant with a device called a hydrogen bomb).
So that's how the cores of most common stars produce all their energy... in fact the sun fuses 600 million tons of hydrogen bare proton nuclei to 596 million tons of bare helium nuclei... every second. The resultant mass loss of 4 million tons is converted to energy with Albert Einstein's famous equation  E = m c squared.
With a total lifespan of about 10 billion years... it's used up about half of the available hydrogen, so we have about 3-5 billion years left on this planet.
95% of all the common stars, bigger and smaller, do exactly the same thing, but with vastly different life spans.
Red giants fuse helium nuclei to carbon and oxygen nuclei... and there are some "dead" stars that fuse nothing, but are just cooling off at the end of their lives... white dwarfs and neutron stars.
But that's another story.
Hope this helps,
Clear Skies,
Tom Whiting
Erie, PA  


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Tom Whiting


Astronomy has been my hobby/pasttime for over 50 years.  Currently own 3 telescopes, the largest of which is a 30 inch Newtonian truss Dob that is portable.I taught Astronomy/Meteorology at the University Level for 13 years before retiring in 1995. Being retired and home most of the time, I am able to answer all questions relatively quickly, unless it's a new moon weekend with good observing conditions.  No astrology questions please, or questions about alleged UFO picture identifications.


Experience: Astronomy has been my hobby and study for over 50 years. We currently now own a 30 inch portable telescope (Updated - Pennsylvania`s largest portable telescope). It can be seen on our website at: and also attend several regional starparties during the year, and have been on 5 total solar eclipse expeditions.

Organizations: President, Erie County Mobile Observers Group for over 15 years.

Publications: Wrote the "Over Erie Skies" newspaper article in our local newspaper for 11 years (1975-86).

Education: Masters Degree- Taught at the University level for 13 years. Retired 20 years -USAF Pilot - KC-135 with 180 combat missions;  Also Eagle Scout, Philmont staff 2 Yrs, Order of Arrow Lodge Chief, Ham Radio (inactive).

Awards: two discoveries: The mini-coathanger asterism in Ursa Minor (the little dipper) And the mini-ladle- another asterism in the bowl of Ursa Minor. Clients: Currently President of the ECMOG as mentioned above.

BS  Metallurgical Engineering Grove City College, PAMaster's Degree, Gannon University, Erie, PA Also retired USAF pilot, 20 years.

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