Ursids

Lore & Background

The Ursids were probably discovered by William F. Denning, who observed them for several years around the start of the 20th century. Sporadic observations followed, but the first coordinated studies did not begin until Dr. A. Bečvář observed an outburst of 169 meteors per hour in 1945. Further observations in the 1970s and ongoing to the present established a relationship with comet 8P/Tuttle.

Peter Jenniskens and Esko Lyytinen discovered that outbursts could occur when comet Tuttle was at aphelion because some meteoroids become trapped in the 7/6 orbital resonance with Jupiter. The Ursids have a particularly narrow stream, prompting veteran meteor observer Norman W. McLeod, III to comment that the Ursids 'must be a compact stream like the Quadrantids. You have to be within 12 hours of maximum to see much.'

Earlier observations described an average radiant of RA=217°, DEC=76°, with maximum occurring at a solar longitude of 270.66 degrees (about December 22), and the duration established as December 17–24.

Reader's Guide

The Ursids are significant as a meteor shower with a narrow stream, making their peak brief and intense. The article notes that veteran observer Norman W. McLeod, III compared them to the Quadrantids, emphasizing that observers must be within 12 hours of maximum to see much activity. The shower's relationship with comet 8P/Tuttle, established through observations in the 1970s and later, provides a key link between a periodic comet and a meteor stream. The discovery by Peter Jenniskens and Esko Lyytinen that outbursts can occur when comet Tuttle is at aphelion, due to meteoroids trapped in the 7/6 orbital resonance with Jupiter, adds a layer of dynamical complexity. The Ursids' legacy includes being probably discovered by William F. Denning around the start of the 20th century, with the first coordinated study prompted by Dr. A. Bečvář's 1945 outburst of 169 meteors per hour. The shower's annual activity runs from about December 17 to December 25 or 26, with a typical maximum around December 22.