April 8
The First Resolution
Sun Position
The Sun is in Aries near +11° declination. Northern hemisphere days are about 90 minutes longer than the equinox baseline; in the southern hemisphere, the days are shortening at a similar rate.
Sky Highlight
Mid-April offers the best annual views of the Coma Berenices star cluster (Mel 111), a scattered naked-eye group of about 40 stars around 280 light-years away. It frames the northern edge of the Virgo Cluster and is one of only three open clusters close enough to span several degrees of sky. Best from northern mid-latitudes.
Deep Sky Object
M85 (NGC 4382), lenticular galaxy in Coma Berenices, about 60 million light-years. M85 is the northernmost Virgo Cluster member in Messier's catalog and an unusually blue lenticular, suggesting a relatively recent merger that triggered a burst of star formation. Visible in a small telescope from northern mid-latitudes; accessible but lower from the southern hemisphere.
Featured Star
Mizar (ζ UMa) returns tonight: two A1V stars at 83 light-years, the first double star resolved through a telescope. The system has since grown more complex with observation. Mizar itself is a spectroscopic binary pair, making what looks like two stars in a telescope actually four stars sharing a common gravitational center.
Around This Date
- April 8, 1964Gemini 1, an uncrewed test flight of the new Gemini spacecraft, launched successfully, validating the heat shield and structural integrity needed for crewed missions.
- April 10, 1970Apollo 13 launched from Kennedy Space Center, bound for the Moon on a mission that would become defined by the oxygen tank explosion two days later.
Mizar looked like two stars in 1650; it turned out to be four, a good reminder that resolution is always provisional.