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
Eye relief

The distance from the eyepiece at which you can see the full field of view. People who wear glasses observe further away from the eyepiece and so need a longer eye relief.

Apochromatic refractor

A telescope that uses three or more lenses to bring red, green and blue light to focus at the same point.


This is when an atom is stripped of or receives electrons. It often happens in astronomy where a gaseous nebula is ionized by stars within it.

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