The middle layer of the sun's atmosphere.

The central core of a comet.

An object that orbits a star, is large enough to become rounded by its own gravity, and has cleared the area of its orbit.

A measure of the force of gravity acting on an object.

An eruption of gas from the sun's surface that occurs when the loops in sunspot regions suddenly connect.

The attractive force between objects.

The name often given to the outer planets: Jupiter, Saturn, Uranus, and Neptune.

The spinning motion of a planet on its axis.

The system consisting of the sun and the planets and other objects that revolve around it.

A streak of light in the sky produced by the burning of a meteoroid in Earth's atmosphere.

The outermost layer of the sun's interior.

The name often given to the four inner planets: Mercury, Earth, Venus, Mars.

The inner layer of the sun's atmosphere that gives off its visible light.

The loose collection of ice and dust that orbits the sun, typically in a long, narrow orbit.

One of the rocky objects revolving around the sun that are too small and numerous to be considered planets.

The process in which two atomic nuclei combine to form a large nucleus, forming a heavier element and releasing huge amounts of energy: the process by which energy is produced in stars.

The central region of the sun, where nuclear fusion takes place.

The path of an object as it revolves around another object in space.

A stream of electrically charged particles that emanate from the sun's corona.

A large cloud of gas and dust in space.

A graph relating the surface temperatures and absolute brightness of stars.

The outer layer of the sun's atmosphere.

The distance that light travels in one year, about 9.5 million kilometers.

Term describing a model of the solar system in which Earth and the other planets revolve around the sun.

Term describing a model of the universe in which the Earth is at the center of the revolving planet and stars.

A contracting cloud of gas and dust with enough mass to form a star.

A region of very tightly packed gas in the sun's interior where energy is transferred mainly in the form of of electromagnetic radiation.

A huge, reddish loop of gas that protrudes from the sun's surface, linking parts of sunspot regions.

A huge burning sphere of gasses held together by gravity.

A dark area of gas on the sun's surface, linking parts of sunspot regions.

The movement of an object around another object.

The fuzzy outer layer of a comet.

Meteoroids that pass through the atmosphere and hit Earth's surface.

A huge group of single stars, start systems, star clusters, dust and gas bound together by gravity.