Fusion changes nuclei inside a star

Slide 1

Fusion changes the centers of atoms

Nuclear fusion combines light atomic nuclei into heavier products. In the Sun, a sequence of reactions converts hydrogen into helium and releases energy.

Slide 2

Repelling nuclei must get close

Positively charged nuclei repel one another electrically. The Sun’s hot, dense core provides conditions in which some can approach closely enough to react.

Slide 3

The products have a different mass-energy balance

The total rest mass after a fusion sequence is slightly smaller than before. The difference corresponds to energy carried by particles and radiation.

Slide 4

Neutrinos carry information outward

Solar fusion produces neutrinos, particles that interact very weakly with matter. Many escape directly from the core and pass through Earth.

Slide 5

Multiple observations test the explanation

Solar models connect fusion rates with the Sun’s output and structure. Neutrinos and solar oscillations provide tests beyond the light visible at the surface.

Sources

• Mass, Energy, and the Theory of Relativity

  OpenStax, Rice University

• The Solar Interior: Observations

  OpenStax, Rice University

• Proton-Proton Fusion: Powering the Sun

  U.S. Department of Energy