Lots of astronomical events are unpredictable — the appearance of a bright comet, for instance. But several times each year you can plan ahead for one of nature's best sky shows: a meteor shower.
The brief streaks of light from meteors, sometimes called "shooting stars," can occur at any time on any night. On a moonless night you might see a half dozen of these sporadic (random) meteors hourly.
However, several times a year Earth encounters a stream of debris left by a passing comet, and the result is a meteor shower. You'll notice the difference if you watch the sky for a half hour or so: not only do the number of meteors you'll see go up, but also the meteors seem to fly away from a common point in the sky (the shower's radiant).
A shower gets its name from the constellation where this radiant lies — for example, August's well-known Perseid shower has its radiant in Perseus. The higher a shower’s radiant, the more meteors it produces all over the sky.One notable exception to this rule is the Quadrantid shower, named for the now-defunct constellation Quadrans Muralis. Instead, its radiant lies in the constellation Boötes. In any case, The higher a shower’s radiant, the more meteors it produces all over the sky.
Meteor showers peak during the predawn hours on the dates listed below, though they're typically active a few nights before and after the peak date. Note that the rates are for ideal conditions: very dark skies free of moonlight or light pollution; most likely you'll see somewhat lower rates than those listed. Following the table are specific predictions for each shower's prospects during 2009.
For the best possible viewing experience, find a dark location, make yourself comfortable in a reclining chair, and wear plenty of warm clothing. And for more information on watching and studying meteors, see Meteors: A Primer and the other articles in the Meteor section of our website.
|Major Meteor Showers in 2009|
|Quadrantid||Draco (NE)||Jan. 3||100|
|Lyrid||Lyra (E)||Apr. 22||10-20|
|Eta Aquarid*||Aquarius (E)||May 6||20-40|
|Delta Aquarid*||Aquarius (S)||July 28||20|
|Perseid*||Perseus (NE)||Aug. 12||60|
|Orionid||Orion (SE)||Oct. 21||10-15|
|Leonid||Leo (E)||Nov. 17||10|
|Geminid||Gemini (S)||Dec. 14||100|
|* Moonlight will wash out fainter meteors in these showers.|
January 3: The Quadrantids
In 2009 this short, sharp shower peaks around 5 a.m. Pacific time, meaning viewers in western North America will have the advantage over those farther east. The Moon won't be a factor, so expect as many as 100 meteors per hour streaming from its radiant in northern Boötes.
April 22: The Lyrids
Although this isn't one of the year's strongest showers, the Moon will be a thin predawn crescent when the Lyrids peak. Count on seeing roughly a dozen or so meteors per hour emanating from a radiant near the Hercules-Lyra border. These are particles from Comet Thatcher (1861 I).
May 6: The Eta Aquarids
This shower is spawned by none other than Halley's Comet. It's typically a good one for Northern and Southern Hemisphere observers, though the radiant, in the Water Jar of Aquarius, rises late for northerners. This year strong light from a nearly full Moon will wash out most of them, so don't expect to see more than 20 or so per hour.
July 29: The Delta Aquarids
Skywatchers in the Southern Hemisphere see the Aquarid showers best because their radiant is below the celestial equator. Light from a last-quarter Moon will be a factor and probably wash out many of the predicted 20 or so Delta Aquarids per hour.
August 12–13: The Perseids
The Perseid shower is a popular display because it offers up to 60 an hour under a summer sky. Showtime usually begins as soon as the radiant (near the Double Cluster in Perseus) clears the horizon, an hour or so before midnight. But not long afterward you'll have competition from a last-quarter Moon. The Perseids' parent comet is 109P/Swift-Tuttle.
October 21: The Orionids
This is another modest shower due to Halley's Comet. Moonlight won't be a problem in 2009, so watch for 10 to 15 hourly meteors that stream from the shower’s radiant, located above Orion’s bright reddish star Betelgeuse.
November 17: The Leonids
Typically the Leonid shower is a weak display, with fewer than a dozen meteors per hour radiating from Leo’s Sickle. But the parent comet, 55P/Tempel-Tuttle, tends to create narrow concentrated streams that can produce brief but prodigious displays. That was the case during the late 1990s, and we might be in for a reprise this year. A predicted pulse of activity on November 17th — with hundreds of meteors per hour — will involve contributions from the comet's spewings in 1102, 1466, and 1533. But the outburst will last only a few hours at most, and the timing is more favorable for eastern Asia than the Americas. Learn more about the prospects here.
December 14: The Geminids
With an average of 100 meteors per hour radiating from near the bright star Castor, this end-of-the-calendar shower is usually one of the year’s best. For this year's performance, the Moon will be new, so its light won't wash out the faint ones. Better still, you don't have to stay up until the wee hours to see them — at mid-northern latitudes, the radiant is well up in the sky by 9 p.m. Geminid meteors come from 3200 Phaethon, an asteroid discovered in 1983.