The kite, and the arc to Arcturus
Boötes looks like a kite or an ice-cream cone, with brilliant Arcturus at the bottom point. The easiest way to find it is to follow the curve of the Big Dipper's handle and "arc to Arcturus."
The man who drives the bears
Boötes is usually read as a herdsman or plowman, walking the northern sky behind his oxen. The very name of his brightest star, Arcturus, comes from the Greek Arktouros, "guardian of the bear," because Boötes appears to drive or watch over Ursa Major and Ursa Minor as they wheel around the pole. The Big Dipper, in this older reading, is his plow or his team of oxen.
The Greeks attached several figures to him. Some called him Arcas, the son of Callisto, set in the sky near his mother the Great Bear. Others named him Icarius, a man taught to make wine by the god Dionysus, who was killed by shepherds who thought he had poisoned them and was raised to the stars in sympathy. Whatever his name, he keeps walking, forever following the bears around the pole.
Arcturus is the first brilliant star to rise in the east on spring evenings. Once you have arced to it from the Dipper, the rest of the kite spreads out above it toward the head of the herdsman.
Boötes at a glance
Abbreviation
Boo · Genitive: Boötis
Brightest Star
Arcturus (α Boo), magnitude −0.05
Famous Double
Izar (ε Boo), "Pulcherrima"
Best Visibility
Spring and summer evenings; northern sky
Key Stars
- α Boo — Arcturus. Magnitude −0.05, the brightest star in the northern half of the sky and the fourth-brightest in the night. A red-orange giant only 37 light-years away. (See its full profile.)
- ε Boo — Izar / Pulcherrima. "The most beautiful." A classic double star: an orange giant paired with a blue-white companion, a colour contrast that splits cleanly in a good telescope. The second-brightest star in Boötes.
- η Boo — Muphrid. A yellow subgiant sitting close to Arcturus in the sky, and a near neighbour in space at about the same distance.
- γ Boo — Seginus. A white giant marking the herdsman's left shoulder, at the top-left of the kite.
- β Boo — Nekkar. A yellow giant at the head of the figure, the top of the kite.
- τ Boo — Tau Boötis. A sun-like star that hosts one of the first "hot Jupiter" exoplanets found, and whose magnetic field flips polarity every couple of years.
The Great Nothing
Boötes is faint on deep-sky objects, but it gives its name to one of the most extraordinary features in cosmology. Looking out through the constellation, astronomers in 1981 mapped a colossal, nearly empty bubble of space now called the Boötes Void. It is roughly 330 million light-years across, one of the largest known voids in the universe, and contains only a tiny scattering of galaxies where thousands would be expected.
The scale is hard to hold in the mind. As one astronomer put it, if the Milky Way had been in the centre of the Boötes Void, we would not have known there were other galaxies until the 1960s. The herdsman points us toward the emptiest country in the cosmos.
Constellation data sheet
| Abbreviation | Boo |
| Genitive | Boötis |
| Area | 907 sq. degrees (13th largest) |
| Brightest star | Arcturus (alpha Boo), mag −0.05 |
| Famous double | Izar (epsilon Boo), orange giant + blue companion |
| Meteor shower | Quadrantids, peak ~January 3 (radiant in northern Boötes) |
| Deep-sky note | NGC 5466 globular cluster; the Boötes Void |
| Bordering constellations | Ursa Major, Draco, Hercules, Corona Borealis, Serpens, Virgo, Canes Venatici |
| Best visibility | Spring and summer evenings, northern latitudes |
Sources & Credits
Star chart above is an original schematic by Michael Paycer. Reference data:
Boötes is the patient herdsman of the spring sky, walking his oxen around the pole behind the brightest star in the north. Look past his kite and he points to the Great Nothing, as if the guardian of the bears were also keeping watch over the empty edge of everything.
Stories in the stars
Boötes the Herdsman drives the bears around the pole, one figure in a wider tapestry of constellation myths. Explore them all on the Greek mythology hub.
Greek Myths Hub · Arcturus · Ursa Major · Hercules · Draco
All Astronomy Notes · Arcturus · Ursa Major · Hercules · Greek Mythology in the Night Sky