January 13
The Belt and the Fourth Moon
Sun Position
The Sun lies in Capricornus, about 21.6° south of the celestial equator. In the Northern Hemisphere the days are still short but lengthening; in the Southern Hemisphere this is high summer with long, warm evenings.
Sky Highlight
Orion's Belt (Alnitak, Alnilam, Mintaka) points down to Sirius and up to Aldebaran, a celestial signpost visible the world over. The three stars sit almost exactly on the celestial equator.
Deep Sky Object
The Flame Nebula (NGC 2024) beside Alnitak, lit by hot young stars about 1,400 light-years away. A telescopic target for both hemispheres.
Featured Star
Alnilam (ε Ori), a blue supergiant in Orion, about 1340 light-years away. Alnilam, the middle pearl of Orion's Belt, a supergiant of enormous power.
Around This Date
- January 13, 1610Galileo recorded a fourth moon of Jupiter, completing the set later called the Galilean moons.
- January 14, 2008MESSENGER became the first spacecraft to fly past Mercury since Mariner 10 in 1974, beginning a series of flybys that would lead to its orbital insertion in 2011.
Three stars in a row, and the whole sky finds its bearings.