The sun: a nuclear powerhouse

conduction

Process by which heat is directly transmitted through a substance when there is a difference of temperature between adjoining regions caused by atomic or molecular collisions.

convection

Movement caused within a gas or liquid by the tendency of hotter, and therefore less dense material, to rise and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat.

fission

Breaking up of heavier atomic nuclei into lighter ones.

fusion

Building up of heavier atomic nuclei from lighter ones.

helioseismology

Study of pulsations or oscillations of the Sun in order to determine the characteristics of the solar interior.

hydrostatic equilibrium

Balance between the weights of various layers, as in a star or Earth’s atmosphere, and the pressures that support them.

neutrino

Fundamental particle that has no charge and a mass that is tiny relative to an electron; it rarely interacts with ordinary matter and comes in three different types.

positron

Particle with the same mass as an electron, but positively charged.

proton-proton chain

Series of thermonuclear reactions by which nuclei of hydrogen are built up into nuclei of helium.

radiation

Emission of energy as electromagnetic waves or photons; also the transmitted energy itself.