December 17
The Southern Beacon
Sun Position
The Sun is in Sagittarius, near 23.4 degrees south declination, within days of the solstice turning point. Northern Hemisphere days are near their shortest; the Southern Hemisphere is in full midsummer.
Sky Highlight
Canis Major is rising in the southeast by late evening for northern observers, bringing Sirius up above the horizon. From the Southern Hemisphere, Sirius is already well placed high in the north-northeast. The broader Canis Major / Puppis region contains numerous bright clusters emerging into good viewing position.
Deep Sky Object
M41, an open cluster in Canis Major about 2,300 light-years away, sits just south of Sirius and is visible to the naked eye from a dark site; binoculars show it well, and a telescope reveals dozens of stars including a red giant near its center.
Featured Star
Canopus (α Car) is an A9II white-yellow bright giant about 310 light-years away, the second-brightest star in the sky after Sirius, and visible only from latitudes south of about 37°N. It is used by spacecraft navigation systems today just as it guided ancient mariners, serving as a stable bright beacon far from the plane of the Milky Way.
Around This Date
- December 19, 1972Apollo 17 splashed down safely, closing NASA's Apollo lunar program; the crew had returned 110 kilograms of lunar samples and performed three moonwalks covering about 35 kilometers of the Taurus-Littrow valley.
- December 12, 1970Uhuru launched, and within its first year of operations returned the first comprehensive catalog of celestial X-ray sources, identifying over 300 objects and establishing X-ray astronomy as a discipline.
Canopus has been guiding things south since before rockets existed, it does not particularly care whether the traveler is a ship or a spacecraft.