Bootes the Herdsman: Finding Arcturus

Bootes (pronounced boh-OH-teez) is a large constellation that dominates the spring and early summer sky in the Northern Hemisphere. Its claim to fame is Arcturus, the fourth-brightest star in the entire night sky and the brightest star north of the celestial equator. The constellation's distinctive kite-like shape makes it relatively easy to identify once you know the trick of following the arc of the Big Dipper's handle. Trace the positions of Bootes and Arcturus in real time with StarGlobe.

How to Find Bootes and Arcturus

The classic method for locating Arcturus uses one of the most famous star-hopping phrases in amateur astronomy: "arc to Arcturus." Start with the Big Dipper in Ursa Major. Follow the curve of the Dipper's handle away from the bowl, extending the arc about 30 degrees, and you will arrive at a brilliant golden-orange star. That is Arcturus. Our guide to the Spring Arc explains this technique in detail.

Once you have found Arcturus, the rest of Bootes takes shape above it. The constellation resembles an elongated kite or an ice cream cone, with Arcturus at the bottom point. The upper portion of the kite spreads out into a roughly triangular shape. The entire figure spans about 35 degrees from top to bottom, covering 907 square degrees and ranking as the 13th-largest constellation.

Arcturus: A Stellar Neighbor

Arcturus shines at magnitude -0.05, making it the brightest star in the constellation and the fourth-brightest in the entire sky after Sirius, Canopus, and Alpha Centauri. Located just 36.7 light-years from Earth, Arcturus is one of our closer stellar neighbors among the bright stars. It is an orange giant star, roughly 25 times the diameter of the Sun and about 170 times more luminous.

What makes Arcturus particularly interesting to astronomers is its motion. It is not part of the disk of the Milky Way like most nearby stars. Instead, Arcturus belongs to an older population and is passing through the solar neighborhood on a different orbital path around the galactic center. Its proper motion across the sky is unusually large, about 2.3 arcseconds per year, which means its position relative to other stars shifts noticeably over centuries. To understand more about how we measure stars, see our article on star magnitude.

Other Stars in Bootes

While Arcturus dominates, Bootes contains several other noteworthy stars. Izar (Epsilon Bootis) is one of the finest double stars in the sky. Its components, an orange giant and a blue-white companion, are separated by just 2.8 arcseconds. The color contrast between the two has earned Izar the nickname "Pulcherrima," Latin for "most beautiful." A telescope at moderate magnification reveals the pair wonderfully, and our guide to double stars includes more targets like this.

Nekkar (Beta Bootis) marks the head of the herdsman at magnitude 3.5. Seginus (Gamma Bootis) is a Delta Scuti variable star that pulsates slightly in brightness. Muphrid (Eta Bootis) sits close to Arcturus in the sky and forms a wide optical pair with it, though the two are not physically related.

Deep Sky Objects

Bootes is not particularly rich in bright deep sky objects for small telescope users, largely because it lies well away from the plane of the Milky Way. However, this same characteristic makes it an excellent region for galaxy hunting with larger instruments. The Bootes Void, a roughly spherical region about 250 million light-years in diameter that contains very few galaxies, is one of the largest known voids in the observable universe and lies in this direction of the sky.

For binocular observers, a few globular clusters and faint galaxies can be found scattered through the constellation. NGC 5466 is a loose globular cluster about 52,000 light-years distant that can be glimpsed in moderate-sized telescopes under dark skies.

The Quadrantid Meteor Shower

Bootes is historically connected to one of the year's best meteor showers. The Quadrantids peak in early January and are named after the now-defunct constellation Quadrans Muralis, which once occupied the area near the border of Bootes and Draco. The radiant point of the Quadrantids lies in the northern part of Bootes. At peak, the shower can produce over 100 meteors per hour, though the peak is notably brief, lasting only about six hours. Read our meteor shower guide for tips on observing the Quadrantids and other annual showers.

Mythology and Cultural Heritage

The identity of Bootes has been interpreted in many ways across cultures. In Greek mythology, the constellation is most often associated with Arcas, the son of Zeus and the nymph Callisto. In this story, Callisto was transformed into a bear (Ursa Major), and Arcas was placed nearby in the sky. Another tradition identifies Bootes as the plowman who drives the oxen of the Big Dipper around the celestial pole, which explains why the constellation follows Ursa Major across the sky.

The name Bootes itself derives from a Greek word meaning "ox driver" or "herdsman." The constellation is one of the 48 listed by the ancient Greek astronomer Ptolemy in the second century, and its recognition likely stretches back much further. Ancient Arab astronomers gave many of the constellation's stars their current names, contributing to the rich multicultural legacy of this star pattern. Learn more about how constellations received their names in our history of constellations article.

Neighboring Constellations

Bootes sits in a rich neighborhood. To its east lies Corona Borealis, the Northern Crown, a small but elegant semicircle of stars. Beyond Corona Borealis is Hercules. To the west, the Big Dipper and Ursa Major provide the star-hopping path to Arcturus. Below Bootes, the constellation Virgo stretches across the southern sky with its wealth of galaxies.

Observing Tips

Bootes is best observed from April through August. Arcturus reaches its highest point in the evening sky around late May, when it transits the meridian at a comfortable altitude for mid-northern observers. The kite shape is best appreciated from reasonably dark skies, though Arcturus itself is easily visible even from urban locations.

For the best experience, use StarGlobe to follow the arc from the Big Dipper to Arcturus. Once you have identified the kite pattern, practice hopping from Bootes to Corona Borealis and then onward to the Keystone of Hercules. This chain of constellations forms a natural path across the spring and summer sky that every stargazer should know.