Perseid meteor shower 2027

Fast streaks, frequent fireballs

Perseids hit the atmosphere at 59 km/s, so most are quick streaks, gone in well under a second. The brighter ones often leave a glowing wake that hangs in the sky for a moment after the meteor itself has vanished.

Fireballs are the shower’s signature. Over the first years of NASA’s all-sky fireball camera network, which began tracking in 2008, the Perseids produced more fireballs than any other annual shower. The runner-up Geminids were slightly fainter at their brightest: magnitude −2.0 on average, against −2.7 for a Perseid.

A ZHR of about 110 is what you would count with the radiant overhead under a perfect sky (see what ZHR means). NASA’s deliberately cautious planning figure for a dark rural site in the United States is about 40 Perseids in the hour before dawn on the peak nights. The latitude table below gives the range an attentive observer can count this year, from a dark site and from the suburbs.

The season is long and lopsided. The first Perseids appear around July 17, rates creep upward through late July and early August, and the shower is over by about August 24: four weeks of build-up against less than two weeks of decline. The timing of the broad maximum varies by about half a day from year to year, so the nights either side of the nominal peak are usually close behind.

These are northern-summer nights, warm but short. At 50°N the sky is fully dark for only about five hours in mid-August, and north of about 60°N it never gets fully dark at all.

Comet Swift–Tuttle and its 26-kilometer nucleus

The parent is 109P/Swift–Tuttle, found independently by Lewis Swift and Horace Tuttle in July 1862. Its nucleus is about 26 km across, while most comets measure only a few kilometers, and NASA credits that size for the many fireball-sized grains in the stream.

Swift–Tuttle takes about 133 years to orbit the Sun, on a path tilted about 113° to Earth’s: it circles the Sun opposite to the planets, so its debris meets Earth nearly head-on at 59 km/s. The comet last passed perihelion in December 1992 and is next due back in the 2120s.

Each of Swift–Tuttle’s passages leaves a fresh trail of dust along its orbit. What Earth crosses every August is mostly an old, broad stream built up over many returns, and the IMO notes that trails more than 20 orbits old are still part of it. Narrow trails from single returns sometimes lie in Earth’s path too, and Jupiter’s gravity slowly shifts parts of the stream toward or away from Earth’s orbit; both make rates differ from year to year.

Following Perseus up the northeastern sky

On peak night the radiant sits in northern Perseus, east of the W of Cassiopeia and about 8° north of Mirfak, the constellation’s brightest star. It drifts roughly a degree east each night, so in late July a Perseid traces back to a point some 25° farther west, toward Cassiopeia.

From 40°N the radiant never sets. It stands about 15° up at 9 p.m. local standard time, 35° at midnight and 65° by 4 a.m.; add an hour for daylight saving time. The visible rate scales roughly with the sine of the radiant’s altitude, so that climb alone more than triples what you see.

The radiant lies only about 40° from the apex, the point Earth is moving toward in its orbit, which rises around midnight and stands highest at dawn; that closeness is also why Perseids arrive so fast. In the evening, while the radiant is low, watch for earthgrazers: Perseids that skim the upper atmosphere on long, unhurried paths up from the northeast.

Mid-northern latitudes are best placed. From the equator the radiant reaches about 30° before dawn. From 20°S it rises around 2 a.m. and gets to only about 10°. From roughly 32°S southward it never clears the horizon, although a stray Perseid can still shoot up from below the northern horizon. Southern observers do better with the Southern Delta Aquariids in the same weeks.

Three other showers overlap the Perseids. The Southern Delta Aquariids and the slow Alpha Capricornids come from radiants low in the south, and the slow Kappa Cygnids peak in mid-August from high in the northwest. A Perseid traces back toward the northeast and is faster than any of them. For general setup, see how to watch a meteor shower.

From the Tears of St. Lawrence to Schiaparelli

Chinese records mention the shower in AD 36. In Europe it became tied to August 10, the feast of St. Lawrence, a deacon martyred in Rome in AD 258. In 1839 the American astronomer Edward Herrick wrote of a belief, held “for ages” in parts of England and Germany, that “the burning tears of St. Lawrence” appear in the sky on that night.

Several astronomers are credited with independently recognizing the August meteors as an annual shower in the 1830s. Within a few years of the comet’s 1862 appearance, the Italian astronomer Giovanni Schiaparelli showed that the Perseid stream travels in Swift–Tuttle’s orbit. It was the first direct link found between a meteor shower and a particular comet.

The comet was expected back around 1982 but did not appear on schedule. Tsuruhiko Kiuchi recovered it in September 1992, and the shower responded. For several years observers recorded a new, sharp maximum alongside the traditional broad peak, and the IMO describes strong activity from it through the 1990s. Earth crossed several separate dust trails for an enhanced return in 2016, and in 2018, 2020 and 2021 observers reported high activity a day or so after the main peak.