Orange giant · Boötes

Arcturus

Also known as: α Boötis (α Boo), HIP 69673

mag 0.037 light-years

About

Arcturus (α Boötis) is an orange giant of magnitude 0.0 in Boötes, about 37 light-years away.

Arcturus is in the constellation Boötes.
Best evenings: around early June it is highest at about 9 pm (10 pm in summer time); a month earlier, two hours later.
Where on Earth: it is seen well, at least 10° up, from north of 61° S.
Star patterns: Spring Triangle.
Spring Triangle: The brightest star of the northern sky, an orange giant 37 light-years away.

When it rises and sets tonight, how high it climbs and how much the Moon gets in the way are worked out in your browser for your place.

EyesOne of the brightest stars in the whole sky — easy even from a city centre. It has a clear orange tint.
Binoculars (10×50)Dazzling, with its colour stronger than to the eye.
Telescope (6–8 inch)Still a point of light at any magnification — stars are too far away to show a disc. Low in the sky, bright stars twinkle and flash colours.

Stars look the same in any instrument: brighter and sharper, but never bigger.

Proper name	Arcturus
Designation	α Boötis (α Boo)
Hipparcos number	HIP 69673
Type	Orange giant
Spectral type	K2IIIp
Colour	OrangeB−V colour index 1.24
Magnitude	0.0The smaller the number, the brighter.
Distance	37 light-yearsThe light you see left it around 1989.
Proper motion	2.28″ per year across the sky
Constellation	Boötes
Right ascension (J2000)	14h 15m 39.7s
Declination (J2000)	+19° 10′ 57″

Star data: HYG Database by David Nash, CC BY-SA 4.0. All data sources →