Comet Biela is the source of a nearly forgotten meteor shower that "stormed" in 1872. The Andromedids were surprisingly numerous two years ago. The shower displayed surprising activity this month.
|Update: Meteor specialist Peter Brown reports that the outburst of Andromedid activity has tailed off and that the shower's peak, based on radar data, occurred on December 6th.|
You'd be forgiven if you've never heard of the Andromedids, let alone that they'd be worth watching. This is a stream of debris shed by the now-defunct Comet Biela, which was discovered three times — in 1772, 1805, and 1826 — before its periodic nature was confirmed. In 1846 this curious interloper returned as two comets traveling side by side.
But Comet Biela is best remembered for the torrent of "shooting stars" it unleashed on November 27, 1872, when thousands of meteors per hour flashed across the sky and Chinese observers noted that "stars fell like rain." In Italy, observer P. F. Denza and three others recorded about 33,400 meteors during a 6½-hour interval! Another storm, though not as intense, ensued on the same date in 1885.
Over time the "Bield" meteors (later renamed Andromedids) has dwindled to near nonexistence. But they returned in 2011 with a zenithal hourly rate of about 50, their strongest showing in more than 100 years. Radar records suggest that the cometary castoffs are quite small and slow-moving, striking Earth at 12 miles (19 km) per second — about the minimum speed possible.
Brown is encouraging amateurs to make visual observations if possible. The radiant is roughly at right ascension 0h 48m and declination +60° — about 10° north of the Andromeda galaxy near the bright star Schedar in the "M" of Cassiopeia. That's nearly overhead as darkness falls, though there's some interference from the waxing Moon.
Brown adds, "It is possible to follow the activity in near real-time as detected by CMOR."