Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Burning Sun
Name: Chris
Status: Other
Age: N/A
Location: N/A
Country: N/A
Date: N/A 

How does the Sun keep burning?

The central part of the Sun is like a nuclear reactor. It combines four Hydrogen atoms to make Helium and some energy in form of radiation. It is this energy that we receive. A star as big as the Sun may live on this reaction for about 9 billion years. We think the Sun is about half that age.

Jasjeet S Bagla

Update - 1/24/2005
We say that the sun is "burning," but it is not burning in a chemical sense like wood or oil. The sun is kept hot by nuclear reactions taking place inside of it, but these are different from the reactions in a nuclear reactor.

Nuclear reactors split heavy atoms (like uranium) to release energy. In contrast, the sun fuses together light atoms (like hydrogen) to release energy.

The hydrogen reaction is more complicated than just four hydrogen atoms (mass 1) fusing together into a helium (mass 4).

The correct sequence is two normal hydrogen nuclei (protons) combine into a heavy hydrogen nucleus (with an electron left over). Then a normal and heavy hydrogen combine into a light helium. Then two light heliums combine to form a normal helium (with two protons left over).

Bob Erck

Click here to return to the Astronomy Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory