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Bright stars · Bootes
Arcturus
Alpha Bootis
Details
Magnitude
-0.05
Spectral type
K1.5III
Bayer
Alpha Bootis
Distance
36.7 ly
The brightest star in the northern celestial hemisphere — a warm orange.
BeginnerWhat is it?
Arcturus is an orange giant about 37 light-years away, roughly 25 times the Sun's diameter. It is the brightest star north of the celestial equator.
What will I see?
Naked eye
A distinctly warm-orange bright star. Find it by following the arc of the Big Dipper's handle down and away.
Reference imagery from long-exposure photography usually shows far more colour and structure than the human eye can see through a telescope.
Observing tips
- The mnemonic 'arc to Arcturus, speed on to Spica' guides you from the Big Dipper.
Interesting facts
- About 37 light-years away.
- Moving through the galaxy at high speed — its position will change noticeably over ~100,000 years.