December 08, 2017


Photographer: Greg Parker 
Summary Authors: Greg Parker; Jim Foster

Shown above is a 2-frame mosaic of brilliant Arcturus, lying about 37 light years from our Sun in the constellation Boötes (the Herdsman). Though it's the brightest star above the Northern Hemisphere (Northern Celestial Hemisphere), shining at a magnitude of −0.05, it's not the brightest star visible to most residents of the Northern Hemisphere; this honor goes to Sirius.

Arcturus, a red giant star, is rapidly touring the Orion Arm of the Milky Way. It likely wasn't visible from Earth 5,000,000 years ago, and at its current velocity will fade from view in another 500,000 years. Only Alpha Centauri has a faster proper motion

In mid-spring, orange-colored Arcturus is high in the sky at midnight, but to see it now you'll need to get up before sunrise -- it's just above the northeastern horizon at sunup. Using a clever manipulation of time and light, and a little showmanship, Arcturus lit the World's Fair in 1933. Note that at Arcturus' 5 o'clock position the alignment of stars called Napoleon's Hat can be seen. Photo taken in late June 2017.

Photo Details: Canon 200 mm lenses; Trius M26C OSC CCDs; taken at the New Forest Observatory.