December 24
Orion's Sword-Foot at the Solstice Dark
Sun Position
The Sun is in Capricorn, near 23.3 degrees south declination. Northern Hemisphere days are only beginning to lengthen; the increase is not yet perceptible without measurement. Southern days are slowly declining from their peak.
Sky Highlight
Orion stands fully clear of the southeastern horizon by 7 PM for mid-northern latitudes, making December evenings among the best of the year for this constellation. For southern observers, Orion is high in the north-northeast and oriented with Rigel at upper right and Betelgeuse at lower left.
Deep Sky Object
M78, the brightest reflection nebula visible in typical amateur telescopes, lies about 1,350 light-years away northeast of Alnitak in Orion, a blue-tinged haze in small telescopes that rewards careful averted vision, the nearest reflection nebula to the Orion Molecular Cloud's main star-forming complexes.
Featured Star
Saiph (κ Ori) is a B0.5Ia blue supergiant about 720 light-years away at the southeastern foot of Orion, returning for a second appearance this month. Its spectral class is nearly identical to Rigel's, but it sits about two magnitudes fainter in the sky; the difference is purely distance, and at Rigel's distance Saiph would be equally brilliant.
Around This Date
- December 24, 1968Apollo 8 astronauts Borman, Lovell, and Anders entered lunar orbit and made their famous Christmas Eve broadcast from the Moon, reading from Genesis and transmitting the iconic Earthrise photograph back to Earth.
- December 25, 2021JWST launched from Kourou; the telescope's deployment sequence would take nearly a month to complete, with teams monitoring each of the 344 single-point-of-failure steps in the unfolding process.
Saiph stands at the foot of Orion on the longest nights of the year, an ordinary-looking star holding an extraordinary secret of distance and fire.