Astrophysics Glossary

Atoms Atoms are the smallest possible pieces of matter. Everything you see around you is made up of atoms.

Coordinates Coordinates are sets of numbers we use to find an accurate position. You can use coordinates to find out where you are in the world, where a point is on a graph, or where a star is in the sky and much more.

Occultations Sometimes in the night sky a star or planet seems to disappear. This can happen because it has gone behind another object in the Solar System such as the Moon or an asteroid. Accurate measurements of the time of an occultation can tell astronomers a lot about the movement, size and shape of the objects.

Reflection of light When light hits a shiny surface like a mirror, it "bounces" off. This is reflection. Flat and curved mirrors are very important in building telescopes.

Refraction of light When light passes between two different type of material (eg from air to glass), it is bent a bit. This is called refraction. Lenses like those in a pair of glasses or in a telescope use refraction.