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
Achromatic

An achromatic lens is one that has been designed to reduce chromatic aberration of light passing through it.

Penumbra

The part of the shadow cast by an eclipsing body that results from the Sun being only partly eclipsed.

Seeliger effect

When a reflective object such as a planet is in solar opposition it will appear brighter in the night sky than when it is not. This effect is named after the German astronomer Hugo von Seeliger.

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