April 1
The Pointer's Vigil
Sun Position
The Sun sits in Aries, with a declination near +4°, just north of the celestial equator. Northern hemisphere days are noticeably longer than nights; southern hemisphere observers are heading into autumn's shortening hours.
Sky Highlight
April evenings offer the best annual window on the Virgo Cluster, the nearest large galaxy cluster at roughly 54 million light-years. No single night outshines another here, but early April finds the cluster at a good elevation after dark across mid-latitudes, making it the defining deep-sky story of the season. Best from both hemispheres, though northern observers have a slight altitude advantage.
Deep Sky Object
M84 and M86 (NGC 4374 / NGC 4406), elliptical galaxies, Virgo Cluster, roughly 55 million light-years. These two giant ellipticals sit so close together in the eyepiece they define the center of Markarian's Chain, a sweeping arc of galaxies visible in a wide-field telescope. Best from northern mid-latitudes; southern observers can see them but at lower altitude.
Featured Star
Merak (β UMa) lies about 79.7 light-years away and is a main-sequence A-type star, a steady white beacon running hotter and brighter than our Sun. It is one of the two Pointer stars in the Big Dipper's bowl; draw a line through Merak and its neighbor Dubhe, extend it five times, and you arrive at Polaris.
Around This Date
- April 1, 1960TIROS-1, the first successful weather satellite, was launched by NASA, opening the era of Earth observation from orbit.
- April 3, 1966The Soviet Luna 10 became the first spacecraft to enter orbit around the Moon, returning data on the lunar gravitational field.
Merak has been pointing toward Polaris for every navigator who ever needed north; it will keep pointing long after we are done looking.