Solar System
Science

The average distance between Earth and the Sun, about 150 million km, or 93 million miles
Astronomical unit
The average distance between Earth and the Sun, about 150 million km, or 93 million miles, is known as an astronomical unit. An astronomical unit AU is a standard measure used to describe distances in space.

The combining of two nuclei to form a single nucleus, this releases energy
Nuclear fusion
The combining of two nuclei to form a single nucleus, this releases energy. Nuclear fusion. In simple terms, nuclear fusion is the process that powers the sun, where smaller atoms merge to form a larger one, releasing energy in the process.

An eruption of gas from the Sun's surface, that occurs when loops in sunspot regions suddenly connect
Solar flare
An eruption of gas from the Sun's surface, that occurs when loops in sunspot regions suddenly connect. Solar flare. It is a sudden, intense burst of radiation from the Sun's surface caused by a magnetic energy release.

One of the four rocky planets of the inner solar system, Mercury, Venus, Earth or Mars
Terrestrial planet
One of the four rocky planets of the inner solar system, Mercury, Venus, Earth or Mars terrestrial planet. A terrestrial planet is a type of planet made mostly of rock and metal with a solid surface.