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Corona Borealis, the Northern Crown, with its brightest star Alphecca, via Fred Espenak and AstroPixels. Used with permission.

Star of the week: Alphecca

Alphecca. Gemma. Alpha Coronae Borealis or simply Alpha Cor Bor. They’re all names for one star – the brightest star in the constellation Northern Crown.

Artist's concept of Kochab seen from its planets via ESky

Kochab and Perked, guardians of north

Two noticeable stars in the Little Dipper are said to guard the north celestial pole because they circle so close to Polaris.

Libra-June-16-AstroBob-cp-2

Is Zubeneschamali green?

Although some scientists claim stars can’t look green, many stargazers will swear that Zubeneschamali proves otherwise.

Zubenelgenubi looks like one star to the eye, but it's actually two stars.   Image via AAO/STScI/WikiSky

Zubenelgenubi is Libra’s alpha star

It’s now Libra’s alpha star. But Zubenelgenubi is an Arabic name indicating that this star was once perceived as the Southern Claw of Scorpius the Scorpion.

Ken Christison captured these glorious star trails around Polaris, the North Star.  He wrote, "For the most common and often the most spectacular star trails, you want to locate Polaris and compose the image so it is centered horizontally and hopefully you can have a bit of foreground for reference."  See more photos from Ken Christison.

Polaris is the North Star

The entire northern sky wheels around Polaris. Some assume it’s the brightest star in the sky. In fact, Polaris ranks only 50th in brightness.

Alpha Centauri

Alpha Centauri, closest to our sun

Third star in the system, a red dwarf called Proxima Centauri, is our sun’s closest neighbor at about 4.22 light-years.

Artist's concept of the star Arcturus

Arcturus cuts through galaxy’s disk

Arcturus is cutting perpendicularly through the galactic disk at a tremendous rate of speed – some 150 kilometers per second.

Kheops-Pyramid

Thuban is a former Pole Star

Thuban was the Pole Star some 5,000 years ago, when the Egyptians were building the pyramids.

alpha-beta-centauri-southern-cross

Hadar is a southern pointer star

Hadar, aka Beta Centauri, joins Alpha Centauri in pointing to the Southern Cross. It’s a triple system. Two of its stars will someday become nearby supernovae.

Artist's concept of Spica from hypothetical planet

Spica is a whirling double star

Spica is a binary star, with two stars larger and hotter than the sun, telescopically indistinguishable from a single point of light.

Image Credit: ESO Online Digitized Sky Survey

Mizar and Alcor, a famous double star

Mizar and its fainter companion star Alcor are located in the handle of the Big Dipper. They are one of the sky’s easiest-to-spot double stars.

Cor Caroli by F. Ringwald, Fresno State

Cor Caroli or Heart of Charles

The star Cor Caroli, or Alpha Canum Venaticorum, is a binary star and the brightest star in the northern constellation Canes Venatici.

Constellation Crux photo by Christopher J Picking in New Zealand.  More information about this photo here.  Used with permission

Mimosa, 2nd-brightest in Southern Cross

You need to be at the latitude of New Orleans, Cairo or New Delhi to glimpse it. From the southern hemisphere, Mimosa is a prominent and beloved star.

Constellation Crux photo by Christopher J Picking in New Zealand.  More information about this photo here.  Used with permission

Acrux, brightest star in Southern Cross

You have to be in the Southern Hemisphere to see Crux – the Southern
Cross – in all its glory. Bluish Acrux, aka Alpha Crucis, is its brightest star.

Credit: Russell Croman

Regulus is the Lion’s Heart

Meet Regulus, brightest star in Leo the Lion.

Alphard.  (North Central Kansas Astronomical Society)

Alphard is the Snake’s Heart

You can see Alphard – the Heart of the constellation Hydra the Water Snake – in the evening in March, April, and May.

Golden Pollux. You almost never see an image of this star in the sky without its fellow star, Castor.  But we chose this image because it shows Pollux' yellowish color.  This image is from a post on ScienceBlogs about seeing red in star colors.

Pollux the brighter Twin star

Being so close together in the sky, Pollux and its brother star Castor are easy to compare. Pollux is brighter and golden in color, while Castor is fainter and white.

Procyon

Procyon the Little Dog Star

The Dog Star, Sirius, is easy to spot because it’s the sky’s brightest star. Procyon – the other Dog Star – is always near its brighter brother on the sky’s dome.

Castor system via Jeremy Perez

Castor is six stars in one

Two stars noticeable for being bright and close together might be Castor and Pollux of the Gemini Twins constellation.

Sirius A and B

Sirius is Dog Star and brightest star

Sirius – in the constellation Canis Major the Greater Dog – is the sky’s brightest star. It’s very easy to spot on winter and spring evenings.