Intro and Visual description
Skywatchers have long-repeated the catch-phrase "Arc to Arcturus" (Arc-TUR-us). Follow the curve of the Big Dipper’s handle to the fourth brightest star in the sky. Arcturus belongs to the ancient constellation Bootes (BOW-oh-tees). Look for a pentagon above Arcturus forming the torso of the herdsman.
Some prefer to see Bootes as a one-scoop ice cream cone. Just to one side lies Corona Borealis, the Northern Crown. With bright Gemma ("Jemma") in its center, like a second scoop of ice cream that melted in the heat of summer and fell off the top.
Arcturus means "guardian of the bear." It is an orange giant over 20 times brighter than the sun, the brightest in the northern hemisphere. Arcturus was the first star to be observed in the daytime, in 1635.
Arcturus moves across the sky against the background of the other stars. This "proper" motion was discovered by Edmond Halley in 1717, and shows that the so-called fixed stars are not completely fixed in their relative positions. You can’t see Arcturus move on any given night, but it is slowly passing by the Sun, and is scheduled to disappear from our sky in just half a million years.
Origin and History
One of the oldest constellations, mentioned in Homer’s Odyssey. Bootes is included in the ancient star catalogs of Eudoxos of Knidos, Aratos of Soli, and Ptolemy.