The shower on May 22, 687 BC (proleptic Julian calendar) was recorded in Zuo Zhuan, which describes the shower as “On day xīn-mǎo of month 4 in the summer (of year 7 of King Zhuang of Lu), at night, fixed stars are invisible, at midnight, stars dropped down like rain.

The Lyrids are a strong meteor shower lasting from April 16 to April 26 each year. The radiant of the meteor shower is located in the constellation Lyra, peaking at April 22—hence they are also called the Alpha Lyrids or April Lyrids. The source of the meteor shower is the periodic Comet C/1861 G1 Thatcher. The Lyrids have been observed for the past 2600 years.

The shower usually peaks on around April 22 and the morning of April 23. Counts typically range from 5 to 20 meteors per hour, averaging around ten. Observers in the country will see more, observers in the city less.

Lyrid meteors are usually around magnitude +2. However, some meteors can be brighter, known as “Lyrid fireballs”, cast shadows for a split second and leave behind smokey debris trails that last minutes.

Occasionally, the shower intensifies when the Earth passes through a thicker part of the dust trail, resulting in a Lyrid meteor storm. In 1982, amateur astromomers counted 90 Lyrids per hour. A stronger storm occurred in 1803, observed by a journalist in Richmond, Virginia:

While the Lyrids might not be cosmic celebrities like August's showy Perseids, the April meteor shower has been known to offer up a surprise or two for sky-watchers

"Although the Lyrids have been observed since 687 B.C., the behavior of the shower from year to year is unpredictable," said Anthony Cook, an astronomer for the Griffith Observatory in Los Angeles.

"An average Lyrid shower produces between 10 and 20 meteors per hour, but occasionally these rates increase to 90 per hour," Cook said. "In 1803 the shower produced about a thousand meteors per hour"—just enough to qualify as a meteor storm.

How to See the Lyrid Meteors

This year, Lyrid meteor activity began picking up on April 16, and the shower will run until April 25.

The Earth Day peak will actually come in the early morning hours of April 22, after the first quarter moon has sunk below the horizon, leaving dark skies. (Test your lunar smarts with our moon quiz.)

"The best time to look will be between the time of moonset [between 1 and 2 a.m., local time] and dawn, and the best way to observe the show is to recline comfortably, facing anywhere from north to east and gazing nearly overhead," Cook said.

"The best location is a region far from urban light pollution with a fairly open horizon."

Lyrids to Be a Sprinkle or a Storm?

The Lyrids' "shooting stars" will appear to radiate from around the brilliant star Vega in the shower's namesake constellation Lyra.

Vega now shines nearly overhead in the predawn hours for stargazers in the Northern Hemisphere. In the Southern Hemisphere skies, the Lyrids will produce just a sprinkling of meteors.

As with other annual meteor showers, the Lyrids are thought to be caused by debris left over from a passing comet. When Earth passes through the trail of particles—most no bigger than grains of sand—the tiny rocks burn up in our atmosphere, creating bright streaks.

(Related: "'Major,' Green Meteor Lights Midwest Night Sky," with video.)

The Lyrids have been linked to the periodic comet Thatcher, which has an orbit that's skewed nearly perpendicular to the plane of the solar system, the tabletop-like plane along which the planets orbit.

The dearth of planets along the comet's path means that its debris trail stays relatively stable, which is most likely why the Lyrids have been a reliable meteor shower for centuries.

But sometimes Earth passes through a particularly dense clump of cometary leftovers, and that's when meteor rates skyrocket.

So are sky-watchers this year in for a sprinkle or a storm?

"The only way to know what the Lyrids have in store for you," Cook said, "is to go outside and observe them."

Tags: lyrids meteor shower 2010, meteor shower, meteor shower april 2010