March 10
The Bear's Thigh
Sun Position
The Sun is in Pisces at declination near +12°; ten days from the vernal equinox, Northern Hemisphere days are clearly ahead of nights, and Southern Hemisphere evenings are shortening visibly.
Sky Highlight
Ursa Major (the Great Bear) is now high in the northeastern sky from northern latitudes by mid-evening. The Big Dipper rides nearly overhead at midnight from latitudes around 50°N in March, making this month among the best for tracing the full constellation without obstruction from horizon haze.
Deep Sky Object
M108 (NGC 3556), an edge-on barred spiral galaxy in Ursa Major, about 46 million light-years away, lying close to Phecda in the Dipper's bowl; it appears as a cigar-shaped smudge in small telescopes and sits conveniently near the Owl Nebula (M97) for a two-for-one field. Northern Hemisphere object, poorly placed from the Southern Hemisphere.
Featured Star
Phecda (γ UMa) is a main-sequence A-type star 83 light-years away with the spectral designation A0Ve, the 'e' indicating emission lines from a circumstellar disk of gas it has spun off due to rapid rotation. It sits in the Dipper's bowl and, unlike Dubhe, is a genuine member of the Ursa Major Moving Group sharing a common origin with most of the Dipper's stars.
Around This Date
- March 10, 1977Astronomers discovered the rings of Uranus during observations of a stellar occultation, catching the star winking out multiple times before and after the planet's disk crossed it.
- March 10, 1982The planetary alignment predicted in the 1974 book The Jupiter Effect occurred on this date, with all nine then-recognized planets on the same side of the Sun within about 95°; despite widespread public alarm about catastrophic earthquakes, nothing significant happened, and even the book's authors had already walked back their predictions.
A spinning disk of gas around a Dipper star, 83 light-years away, even the quietest-looking members of a familiar pattern have something going on.