Archives: Glossary: 691 terms

An annular solar eclipse happens when the Moon covers the Sun's center, leaving the Sun's visible outer edges to form ...

Matter consisting of particles with charges opposite that of ordinary matter. In antimatter, protons have a negative charge while electrons ...

A point that is on the direct opposite side of a planet.

The point of greatest separation of two stars, such as in a binary star system.

The diameter of a telescope's main lens or mirror and the scope's most important attribute. As a rule of thumb, ...

Aphelion is the point farthest away from the Sun on Earth's elliptical orbit.

The point in the orbit of the Moon or other satellite where it is farthest from the Earth.

The apparent brightness of an object in the sky as it appears to an observer on Earth. Bright objects have ...

A small planetary body in orbit around the Sun, larger than a meteoroid but smaller than a planet. Most asteroids ...

A solid body orbiting the Sun that consists of metal and rock. Most are only a few miles in diameter ...