Throwback Thursday: What is a variable star? (Synopsis)

“To be is to be the value of a variable.” –Willard Van Orman Quine

Those constant, fixed points of light in the night sky -- the stars -- turn out not to be so constant if you looked with great precision at them. A star like our Sun varies in brightness, periodically, by about 0.1% over the span of a few years, but many stars vary by 99% or more from brightest to dimmest.

Image credit: British Astronomical Association Variable Star Section, via Image credit: British Astronomical Association Variable Star Section, via

For centuries, we knew of only a handful of these objects, yet now they're known to be commonplace. What causes this spectacular behavior, how did we discover it and what's the physical mechanism underlying it?

Image credit: NASA, ESA and A. Nota (STScI/ESA). Image credit: NASA, ESA and A. Nota (STScI/ESA).

Come learn about the science of variable stars on this edition of Throwback Thursday!

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Well, as far as I'm aware, there are three types of variable.

Inherently variable. Stars that change their luminosity.

Multistar variables. Objects that change their luminosity because they appear to be a singe object when they are not.

Occulted variables. Stars that have their brightness changed by having something dark move in front of them.

I think that WOW is Ethan's alter ego.

Not a chance.

I thoroughly enjoyed the whole article. Thanks!

By Bradley Dean S… (not verified) on 01 Aug 2015 #permalink