Sky Talk January 2009: A Celestial Snowshower

One of the richest yet most ignored annual displays of “shooting stars” starts off the new year with a bang celestially. It’s the Quadrantid Meteor Shower, which promises to put on a fine show this year during the early morning hours of January 3rd. Seen during its peak activity under very dark-sky conditions away from city lights, some skywatchers have likened it to driving through a gentle snowfall at night.

Among the meteor showers to grace our skies each year, that known as the Quadrantids outranks nearly all of them, including the famed Perseids in August. Its peak hourly rate is only matched by that of the Geminids in December (which were unfortunately wiped out by bright moonlight last month). Under clear, dark-sky conditions, observers can expect to see 100 or more shooting stars per hour at its peak (compared to about 80 for the Perseids). This year the shower occurs on the morning of January 3rd, with maximum activity coming at 7:50 a.m. EST. This is about the same time as sunrise on the East Coast, meaning that the last hour or so of the shower’s maximum will happen in a brightening sky. Another source of light interference that’s always a concern during meteor showers is that of the Moon. It will be at its first-quarter phase on the 3rd and will have set before midnight, so the hours between then and dawn will be dark as activity builds toward the peak.

Most meteor displays can be seen for several nights/mornings before and after peak activity, but the Quadrantids have the shortest duration of any major shower, averaging only about 14 hours. Under good conditions, this still means meteors can be seen the evening before. The radiant — that point in the sky from which they appear to stream — lies in the constellation Bootes. And although it doesn’t rise until after midnight in January, meteors can be seen shooting over the northeastern horizon after twilight ends if the sky is dark. However, as already mentioned, this year the Moon will be in the evening sky at the same time, greatly reducing the number of “snowflakes” seen.

Meteoric activity will increase throughout the morning hours because Bootes continues to rise higher in the sky. (Set your Scientifics Star and Planet Locator (#30092-27) for 1:00 a.m. on January 3rd and watch this kite-shaped constellation climb higher in the sky as you wheel the star chart into the morning hours.) But there’s another more significant factor at play here. During the evening we’re on the side of the Earth “facing away” from the direction the meteors are coming and they have to “catch up” with us. But after midnight we’re turned into the direction of the radiant, causing the meteors to slam into the atmosphere at much higher speeds — resulting in many more of them being seen, and those that are seen to generally be brighter and more spectacular.

A final note. Since meteor watches typically run many hours, reclining on a lawnchair is usually recommended. But on a frigid January night, you may prefere instead to remain standing and keep moving to stay warm. And a thermos of coffee or hot chocolate is also highly recommended!

–James Mullaney
Former assistant editor at Sky & Telescope magazine and author of five books on stargazing.


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