March 31
The Southern Beacon
Sun Position
The Sun is in Aries at roughly +7° declination; as March closes, the Northern Hemisphere has 30 days of accumulated spring behind it, and Southern Hemisphere observers are a week past the autumn equinox.
Sky Highlight
Vela and Puppis are well-placed in the south for southern-hemisphere observers on March evenings, and the former ship of the Argo (split across Carina, Vela, and Puppis) dominates the southern Milky Way. For northern observers, this region is low on the horizon or entirely below it: the ship of the Argonauts belongs to the southern sky.
Deep Sky Object
NGC 2547, an open cluster in Vela about 1,400 light-years away, young enough (about 30 million years old) to still contain hot blue stars alongside cooler members; it is bright enough for binoculars and is a useful calibration target for stellar age studies. Best from latitudes below +30°.
Featured Star
Suhail (λ Vel) is an orange supergiant 545 light-years away with spectral class K4.5Ib-II, a luminous, cool, late-type supergiant radiating in deep orange. In Arabic tradition, the name Suhail was also applied to Canopus, one of the sky's most brilliant stars, as a general term for a southern beacon; the shared name reflects how prominently both stars marked the southern horizon from the Arabian Peninsula.
Around This Date
- March 31, 1966Luna 10 launched from the Soviet Union; it became the first spacecraft to orbit the Moon, completing its first lunar orbit on April 3, 1966.
- March 31, 1596René Descartes was born; his development of analytic geometry provided the mathematical language (coordinate systems, algebraic curves) that underpins orbital mechanics and the quantitative description of every path traced by objects in the sky.
The ship of the Argonauts has sailed south for good. March ends with Suhail carrying the name of a southern beacon across 545 light-years of open sky.