Astronomy for Beginners

Here’s where you’ll find observing guides, how-to articles and great astronomy hints and tips. Don’t forget to also check out our comprehensive astronomy dictionary.

Astronomy Dictionary
Dioptre

A measurement of the optical power of lenses and curved mirrors in telescopes and binoculars. The dioptre is the reciprocal of the lens or mirror’s focal length in metres.

Ghost crater

These are craters who have been infilled, buried or submerged by geological processes but are sometimes still just visible on the surface of a planet or moon.

Albedo

This is a measure of how reflective a surface is – the ratio of the amount of electromagnetic radiation (like visible light and infrared) reflected by a surface, to the amount that falls on it.

We use cookies to improve your experience of our website. Cookies perform functions like recognising you each time you visit and delivering advertising messages that are relevant to you. Read more here