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
Altazimuth Mount

A type of telescope mount that is simpler to construct than an equatorial mount, but requires simultaneous movement about the vertical (altitude) and horizontal (azimuth) axes to track a celestial object.


Seeing is a measure of how steady the atmosphere is. It is particularly important to lunar and planetary observers. The worse seeing the more turbulent the atmosphere and therefore the poorer the view through the telescope.

Semi-apochromatic (APO) refractor

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