Each week, we’ve been bringing you different things that you can go outside and look up to see. This week, since we’ve been talking about eclipsing binaries on a regular basis, it seems like a good time to point out an eclipsing binary. And there just happens to be one easy to see that on Saturday night, about 12:46 am, as Saturday passes into Sunday for those of you on the east coast of the United States, or at 9:46 for those of you in the Pacific time zone. 

At that time, the star Algol will reach its faintest magnitude. We have finding charts up on our website that will allow you to locate this star. It’s actually in a really cool ‘V’ of bright things you can look at, ranging from Betelgeuse arching through Aldeberaan down to the planet Mars. 

As you spike back up through the other arm of the V, it carries you through the constellation Perseus. And if you go out right after sunset on Saturday, you’ll see Algol about its regular brightness, a little bit fainter than the star above it if you look north, and as the night goes on, its brightness is going to fade away until it’s significantly fainter than many of the other stars that are in Perseus around it. 

If you want help finding this and if you want comparison stars to compare the brightness, we’ve got it all on our website, DailySpace.org. This is your chance to see an eclipsing binary eclipse.

If you are interested in observing more variable stars like this one — both systems you can see with your unaided eye or observer with binoculars and telescopes — you should check out the American Association of Variable Star Observers. This Massachusetts-based nonprofit brings together data on variable stars collected by volunteers of every type and makes them available to researchers for free. The organization played a major role in last year’s dimming of Betelguese, which is a story we’ll be updating you on tomorrow.

More Information

Sky & Telescope article

Beta Persei (Algol, the “Demon Star”) (Skyscrapers, Inc.)

Algol finder chart (University of Hawai’i)

AAVSO website