Star
Arcturus
Arcturus is the bright orange star of Boötes, the brightest star in the northern half of the sky, and your reward for following the Big Dipper's handle. The name is Greek for guardian of the bear.
Where the name comes from
Arcturus comes from the Greek Arktouros, the guardian or keeper of the bear, because it follows Ursa Major, the great bear, around the sky. It is one of the brightest stars in the whole northern sky, an unmistakable warm orange.
A visitor passing through
Most bright stars drift along with us around the centre of the galaxy. Arcturus does not. It is cutting across our neighbourhood at a steep angle and a high speed, part of an older population of stars that loops through the galaxy’s halo. It is only passing through, and in a few tens of thousands of years it will have moved on and faded from our sky.
What kind of star it is
Arcturus is an orange giant, a star older than the Sun that has run low on hydrogen in its core and swollen outward. The catalogue Hali uses puts its brightness at about magnitude 0, level with Vega. Its light opened the 1933 Chicago World’s Fair. Astronomers caught it with a telescope and a photocell and used the current to switch on the lights, a nice piece of theatre based on the idea, then believed, that the light had left the star around the time of the previous Chicago fair in 1893.
How to find it
Arcturus is easiest on spring and early summer evenings from the northern hemisphere, when it is high in the south and often the first star to appear after sunset. The Big Dipper’s handle points straight to it. By Hali’s star positions it never sets anywhere north of about 71 degrees north.
Arcturus in a chart
By Hali’s 2026 star positions Arcturus sits at 24 degrees of the sign Libra, almost exactly the same degree as Spica, and the Sun reaches that degree around 17 October each year. Ptolemy gave Arcturus the nature of Mars and Jupiter, and it is one of the fifteen Behenian stars. Astrologers who use fixed stars read a planet or angle on it as a pathfinder’s star, success through going a different way from everyone else.
Common confusions
Arcturus and Spica share a zodiac degree but sit far apart in the sky, Arcturus high and orange, Spica low and blue-white. The zodiac degree only measures how far along the Sun’s path each one lies, not how close they are to each other. The Big Dipper page shows the arc that leads to both.
Questions
How do I find Arcturus?
Follow the curve of the Big Dipper's handle away from the bowl. Carry that arc onward and it lands on Arcturus. Stargazers remember it as "arc to Arcturus".
Is Arcturus the brightest star in the sky?
Not quite. Sirius, Canopus and Alpha Centauri are brighter, but all three are in the southern half of the sky. Arcturus is the brightest star north of the celestial equator.
Sources: Star name scholarship and standard stellar references. Hali star positions for 2026, from Yale Bright Star Catalogue coordinates.