The Sun

Nuclear fusion

the process by which nuclei of small atoms combine to form a new, more massive nucleus; the process releases energy

Radiative zone

the zone of the sun's interior that is between the core and the convective zone and in which energy moves by radiation

Convective zone

the region of the sun's interior that is between the radiative zone and the photosphere and in which energy is carried upward by convection


the visible surface of the sun


the thin layer of the sun that is just above the photosphere and that glows a reddish color during eclipses


the outermost layer of the sun's atmosphere


a dark area of the photosphere of the sun that is cooler than the surrounding areas and that has a strong magnetic field


a loop of relatively cool, incandescent gas that extends above the photosphere and above the sun's edge as seen from Earth

solar flare

an explosive release of energy that comes from the sun and that is associated with magnetic disturbances on the sun's surface

coronal mass ejection

coronal gas that is thrown into space from the sun


colored light produced by charged particles from the solar wind and from the magnetosphere that react with and excite the oxygen and nitrogen of Earth's upper atmosphere; usually seen in the sky near Earth's magnetic poles