Then and now

Celestial News & Events

The Fall and Rise of Betelgeuse

With its recent uptick in brightness, Betelgeuse appears to be slowly returning to normal. But will it? Astronomers urge us to keep watch.

V Sagittae Finder Chart

Stellar Science

Mark Your Calendar: Stellar Fireworks Predicted for 2083

According to Bradley Schaefer (Louisiana State University), the 11th-magnitude variable star, V Sagittae, will outshine Sirius and maybe even Venus — despite its distance of some 7,500 light-years.

Betelgeuse in Orion

Explore the Night with Bob King

Betelgeuse is Dimming . . . Why?

The bright star Betelgeuse has faded to a historic low as astronomers try to figure out why.

Boyajian's Star (art)

Stellar Science

Are There More Stars Like Boyajian’s Star?

Remember KIC 8462852, better known as Boyajian’s star (or you may have seen it referred to as the “alien megastructure” star)? We still don’t have a definitive explanation for this source’s odd behavior — in part because we thought that Boyajian’s star was one-of-a-kind.

Pro-Am Collaboration

From Lunar Flashes to Variable Stars: Pro-Am Astronomy Projects

Track satellites, spot flashes on the Moon, monitor violent stars — learn how amateur astronomers can become involved in professional science.

Astronomy and Stargazing Projects

Hunting Bright Variable Stars in M5 and M13

Globular clusters are packed with variable stars, some of which are easy to see and follow in amateur telescopes. We explore M5 and M13, two of the season's finest.

Explore the Night with Bob King

Mira Makes January Nights "Wonderful"

Mira, one of the easiest-to-observe pulsating variable stars, reaches peak brightness this month. Don't be shy, come look her in the eye. 

The Milky Way from Australia

History and Sky Lore

Aboriginal Australians Observed Red Giant Stars’ Variability

New interpretations of oral accounts by Aboriginal Australians show that they included references to the variability of red giants Antares, Betelgeuse, and Aldebaran.

Sharpen Your Skills on Sharpless 2-132

Explore the Night with Bob King

Plant Your Eyes In Delta Cephei's Fertile Triangle

The famous variable star Delta Cephei unlocks a box deep-sky treasures in a little-visited corner of Cepheus, the King.

AR Scorpii: white dwarf and red dwarf binary

Stargazer's Corner: Adventures Under the Night Sky

Amateurs Help Discover Pulsing White Dwarf

Amateur astronomers worked together with the pros in the discovery of the pulsing white dwarf in the variable system known as AR Scorpii. Hear from Josch Hambsch, one of the amateurs on the team, on what it was like to take part.

Gaia14aae, artist's conception

Explore the Night with Bob King

Violent Lights For September Nights

Find out how two closely-orbiting stellar pairs create fireworks you can see in your own backyard telescope.

Variable Stars

Meet My Variable Friend SS Cygni

Get acquainted with SS Cygni, the sky's brightest cataclysmic variable star. It's guaranteed to keep you on your toes.

Stellar Science

The Chaotic Music of Variable Stars

Space-based observations of RR Lyrae variable stars, once considered the paragon of simplicity, are revealing turmoil in their daily vibrations.

Stellar Science

Surprise Variable Stars

Astronomers have discovered an unexpected class of variable stars in the open cluster NGC 3766. The stars are problematic for current theories of star behavior and raise perplexing questions about why the stars are variable at all.

Stellar Science

Amateurs Monitor Controversial Variable Star

SS Cygni, one of the most-watched variable stars, lies at a distance that’s hotly disputed. The truth will determine whether we understand how these types of variables work.

Celestial News & Events

Yet Another Nova in Sagittarius

For the fourth time this year, a star has erupted into prominence in the same constellation. This one is relatively bright and easy to spot from your backyard.

Celestial News & Events

Possible Nova in Sagittarius

If you've got a clear, dark view toward the southern horizon, try your hand at spotting a flaring star that has brightened to near 9th magnitude in northwest Sagittarius.

Professional Telescopes

Vast New Trove of Variable Stars

Newly online: light curves for 198 million stars. The latest great mass of variable-star data comes from the Catalina Sky Survey — which is actually looking for asteroids.

Variable Stars

The Top 12 Naked-Eye Variable Stars

Lurking in the seemingly changeless constellations are a few inconstant stars that pulse and eclipse. Here are a dozen variables that are easy to observe.

Celestial News & Events

Citizen Sky Wants You!

Backyard astronomers of all types and experience levels can participate in a real-world science project — and help solve a mystery involving the star Epsilon Aurigae that's puzzled astronomers since 1821.

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