Variable Stars

All stars appear to twinkle due to our ever-turbulent atmosphere. But some truly do rise and fall in brightness. These so-called variable stars seem to pulsate — either because a star is in a binary system and its companion often eclipses it, or because the star itself periodically swells and shrinks, pulsating in brightness. Polaris, the north star known for being so constant, is itself a variable star.

Sky & Telescope can help you monitor these dancing stars, providing valuable research to astronomy. For more than a century amateur astronomers have helped scientists monitor these stars, collecting nearly all the brightness data on record for hundreds of variable stars.

Chi-Cyg-IR-by-Gavin_m2

Chi Cygni’s Record-Breaking Maximum

The red, Mira-type variable star Chi Cygni has had a very unusual maximum. It's one of the brightest such variables to begin with (typically peaking at about magnitude 5.2), but in late July and early August 2006, it peaked at about magnitude 3.8.

Nova Delphini 1967

Nova Hunters

Few observers have spotted an ever-elusive "new" star. Fewer still have done it twice. Observing styles and techniques are as varied as the searchers themselves.