Lyrid meteor shower 2027

Modest rates, with a history of surprises

In an ordinary year the Lyrids are a mid-sized shower. The International Meteor Organization uses a working ZHR of 18. Its analysis of returns since 1988 found that the peak arrives at a slightly different moment each year, spread over about seven hours. Years when the peak hit the usual position reached ZHRs near 23, and years when it drifted reached closer to 14, a pattern the IMO says still needs confirming. From a good rural site with the radiant high before dawn, that works out to roughly 10 meteors an hour.

The peak is neither knife-edged nor broad. Rates stay above half their maximum for about a day and a half on average, though that has ranged from 15 to 62 hours. The very best rates usually last only a few hours.

Lyrids enter the atmosphere at 49 km/s, quicker than the Geminids and slower than the Perseids. Most don’t leave long glowing trains, though the shower turns out an occasional fireball. Near the highest rates, observers sometimes notice a brief rise in the number of faint meteors, a hint of the fine structure described below.

The season shapes the night. In the north the shower falls in mid-spring, mild compared with the January and December showers, but the nights are already shrinking. At 50°N full darkness lasts only about five and a half hours on the peak night.

Old dust from a 415-year comet

The parent is comet C/1861 G1 (Thatcher), found by A. E. Thatcher on April 5, 1861. It is a long-period comet. Its orbit stretches out to about 110 AU and brings it back roughly every 415 years, tilted almost 80° to Earth’s orbit. At its closest it passes 0.92 AU from the Sun, just inside Earth’s distance. Dust released in 1861 is still traveling with the comet far out along that orbit, and Thatcher is not due back for more than two centuries. The Lyrids seen today come from dust shed on earlier passes.

The comet’s orbit nearly grazes our own. In the 1860s the Austrian astronomer Edmund Weiss computed that it passes within about 0.002 AU of Earth’s orbit, at the point Earth reaches around April 20. Old dust spread all the way around that orbit gives the reliable annual shower.

The outbursts point to something finer. A review of the best-timed outbursts found them packed into a very narrow slice of Earth’s orbit, about six hours ahead of the normal maximum. They were made up mostly of faint meteors. That suggests a thin filament of small particles, perhaps 100,000 km across, which Earth crosses in about an hour. Because the filament doesn’t produce a burst every year, its particles must be clumped along its length.

Watching the radiant climb past Vega

The radiant sits in Lyra near the Hercules border, about 8° southwest of Vega, less than a fist’s width at arm’s length. At 40°N it rises in the northeast around 8 p.m. local standard time (9 p.m. daylight time). Watching is worthwhile from about 10:30 p.m. By midnight the radiant is roughly 40° up, and by the time morning twilight begins it is nearly overhead. The pre-dawn hours are the best by a wide margin.

Southern observers can still see the shower, at a cost. From 30°S the radiant rises close to midnight and is only about 25° high when the sky starts to brighten, which cuts rates to less than half. From the tropics it does better, climbing above 50° by dawn near the equator. Far north, the problem is the reverse: at 55°N the radiant is well placed, but the night gives only about four hours of full darkness.

Two other showers share the late-April sky. The weak, variable π-Puppids come from far southern Puppis and are slow, at 18 km/s. They are mostly a Southern Hemisphere, before-midnight affair. The Eta Aquariids begin in the second half of April. Their much faster meteors come from low in the east in the last hours before dawn. A Lyrid traces back toward Vega and moves at a middling speed between the two. The general basics, from dark adaptation to what to bring, are in how to watch a meteor shower.

Twenty-seven centuries of Lyrid records

The oldest record attributed to the shower comes from China in 687 BCE and describes stars falling like rain at midnight. In 1867 Johann Gottfried Galle confirmed that the Lyrids and comet Thatcher share an orbit. He also traced the shower’s history back to that ancient entry.

The modern story starts in 1803. In the early hours of April 20, newspaper accounts from Richmond, Virginia, and elsewhere in the eastern United States described meteors falling for hours. A later reconstruction put the rate at roughly 670 an hour, a true storm. Those reports led Edward Herrick to suspect a regular April shower, and in 1839 his own observations confirmed it.

The 20th century brought short, sharp outbursts instead of storms. In 1922 an observer in Greece counted about 96 an hour. In 1945 observers in Japan logged 112 meteors in 67 minutes, most of them Lyrids. The best-studied burst came in 1982, when observers in the United States recorded a short-lived ZHR of about 90. Radar at the Springhill Meteor Observatory in Canada showed that the strongest part lasted only about 22 minutes between half-maximum points. As with the earlier bursts, faint meteors made up most of it.