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
Comatic aberration (coma)

An optical defect in a lens, which means light rays that enter the edge of the lens at an angle converge so as not to be brought to a sharp focus. The result is a smearing of detail towards the edge of the field of view.

Light curve

A light curve is a graph of the brightness of an astronomical object. It’s usually applied to variable stars, novae or stars that are transited by extrasolar planets.

Contact binary stars

Two gravitationally bound stars (a binary star system) that have both filled their ‘Roche lobes’. These are teardrop-shaped regions around each star in the binary system, within which matter is gravitationally bound to each star. Any matter beyond a star’s Roche lobe will fall onto the other star in the binary system.

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