Astro Bob: Possible Leonid meteor outburst Nov. 18-19
We may get a strong but brief burst of meteors around midnight Central time Friday night, Nov. 18 as Earth crosses a trail of comet debris dumped in 1733.
Long-time skywatchers fondly recall the spectacular 2001 Leonid (LEE-uh-nid) meteor shower when fireballs (extra-bright meteors) shot all over the sky that mid-November morning. To this day it's the best shower my family and I have ever seen.
Leonids originate from Comet 55P/Tempel-Tuttle which was discovered in late 1865-early 1866 by astronomers Wilhelm Tempel and Horace Tuttle. Comets are generally quite small, typically under 6 miles (10 km) wide, and composed of dust-rich ices, water ice being the most common. Every time a comet circles the sun, solar heating vaporizes some of the ice which frees the dust to spread out and form a tail.
Material in the tail gets deposited along the comet's orbit as a ribbon of dust and debris that resembles a groove on an LP record. After many orbits multiple "grooves" or ribbons are laid down, some richer in dust than others depending on how active the comet was during its passage of the sun.
Every year in November, Earth crosses the orbit of Comet 55P/Tempel-Tuttle and the debris circulating within it . This year that occurs on the morning of Nov. 17 and 18. As we plow on through, dust and bits of rocky grit strike the atmosphere at the incredible speed of 160,000 miles an hour (71 km/sec) and produce glowing streaks of light called meteors or "shooting stars." During a typical Leonid shower, you might see 10-15 meteors per hour from a dark sky. If a bright moon shines, figure on half that.
Meteor counts spiked in 2001 because the Earth passed through two denser ribbons of dust laid down by the comet in 1767 and 1866. You can picture it as the difference between driving through snow flurries (the usual Leonids) and a snowstorm (a thick "filament" of debris). The more material, the more meteors!
On Friday morning, Nov. 18, you'll see a few Leonids as per usual. But I want to direct your attention to late Friday night and early Saturday morning (Nov. 19). That's when meteor shower experts predict that the Earth will pass very close to a dense ribbon of material deposited by the comet in the year 1733. It's a quick trip, lasting from just midnight to 12:30 a.m. Central time (1-1:30 a.m. Eastern).
During that brief time we could see a sudden increase in bright meteors coming from the eastern direction. You're in luck if you live in the eastern half of the country or South America, since Leo rises around 11:30 p.m. local time. At midnight, the radiant stands ~15° high from the Midwest — with no moon to spoil the fun.
Meteor rates could briefly peak at 150-plus an hour from a moderately dark location and even higher from rural areas. Don't abandon all hope if you live in the Western U.S. as it may be possible to see at least some meteors shooting up from below the horizon at that time.
Predictions are good for these sorts of things, but times can vary a bit since our understanding is imperfect. It never hurts to start a little earlier. If activity lags, stick around a little later. Face east for the best view. Now that it's November, I dress for winter and watch from under a blanket on a foldout recliner tipped two-thirds of the way back. If you see the outburst, please leave a note on my Facebook page or by e-mail, and I'll forward that information to the International Meteor Organization . Now let's hope for clear skies!