March 21
A Plank of the Argo
Sun Position
The Sun has moved into Aries (by tropical zodiac convention), declination just above 0° and climbing; the Northern Hemisphere has crossed into its longer-day half of the year, and the Southern Hemisphere into its shorter.
Sky Highlight
The day after the equinox, the pace of change is at its fastest: sunrise is advancing and sunset is retreating by roughly two minutes each per day in the Northern Hemisphere. Carina is well-placed for southern observers this evening, with the false cross and its surrounding star fields riding high.
Deep Sky Object
NGC 3114, an open cluster in Carina, about 3,000 light-years away, large and bright enough for binoculars; it contains over 150 stars and spans about a degree of sky, making it one of the richer naked-eye clusters in the southern Milky Way. Best from Southern Hemisphere; invisible from northern Europe.
Featured Star
Aspidiske (ι Car) is a white supergiant 690 light-years away with spectral class A8Ib, one of the intrinsically more luminous A-type supergiants in the sky. Its name comes from the Greek for 'little shield' or, in older translations, 'a plank of the Argo,' connecting it to the mythological ship whose dismembered constellation (Argo Navis) was split into Carina, Vela, and Puppis in the 18th century.
Around This Date
- March 21, 1965NASA approved the Manned Orbiting Laboratory program (MOL) for early development, a military space station concept that was eventually cancelled in 1969 before any crewed flights occurred.
- March 21, 1762Nicolas-Louis de Lacaille died in Paris at age 49, having catalogued 9,766 southern stars and created 14 new constellations in just four years of observation at the Cape of Good Hope, a productivity rate unmatched in the history of observational astronomy.
A plank of a mythic ship, still afloat 690 light-years out in the keel of the dismembered Argo.