Every August, usually when many people go vacationing in farming areas where skies are dark, a famous Perseid meteor shower makes a appearance. The meteor showering peaks overnight tonight and early Friday (Aug. 11-12).
August is also a month of “The Tears of St. Lawrence.”
Laurentius, a Christian deacon, is pronounced to have been martyred by a Romans in A. D. 258 on an outside iron grill. In a midst of this torture, Laurentius was pronounced to have cried out, “I am already roasted on one side and, if thou wouldst have me good cooked, it is time to spin me on a other.” [Perseid Meteor Shower 2016: When, Where How to See It]
Regardless of either this indeed happened (some trust that a story is a product of dim Gothic imagination), King Phillip II of Spain positively believed it: He built his nunnery palace, famous as “El Escorial,” formed on a building devise of a holy gridiron. St. Lawrence’s genocide is commemorated each year on his feast day (Aug. 10).
To this day, a stately Perseids — that rise each year between approximately Aug. 8 and Aug. 14 — are referred to as St. Lawrence’s “fiery tears.”
You can watch a Perseid meteor showering online around a free live webcast by a Slooh Community Observatory. The four-hour webcast starts during 8 p.m. EDT (0000 GMT). You can also watch a Perseids meteor showering webcast on Space.com, pleasantness of Slooh.
But a commencement record of Perseid meteor activity goes behind some-more than dual centuries before a martyrdom of St. Lawrence: Chinese annals from A.D. 36 state that “more than 100 meteors flew thither in a morning.”
Today, we know that those burning darts of light are indeed a outcome of Earth’s annual communication with a trash left behind by a vast litterbug — a comet.
Swift-Tuttle: Mother of all Perseids
On a night of Jul 15, 1862, an problematic pledge astronomer named Lewis Swift was scanning a sky with his 4.5-inch (11.4 centimeters) Fitz refractor telescope from farming Marathon, New York. In a matter of minutes, Swift ran opposite an intent in a low constellation of Camelopardalis, a Giraffe, that he believed to be Comet Schmidt, that had been detected usually a integrate of weeks earlier. [Perseid Meteor Shower 2016: Sky Maps Guide (Gallery)]
Swift done no grave proclamation of his find — until astronomer Horace Tuttle of Harvard College Observatory exclusively found a same intent 3 nights later. But that object, it incited out, was not Comet Schmidt, yet a totally new specimen. The dual group common a discovery, and a comet therefore perceived both of their names: Swift-Tuttle.
When it was initial seen, Swift-Tuttle could usually be noticed with a telescope. But in a nights that followed, it brightened rapidly. By a finish of Jul 1862, a comet became dimly manifest to a exposed eye, and during Aug it began to boost a suit opposite a sky, flitting 7 degrees from Polaris (the North Star) around Aug. 15 and afterwards stability south opposite a sky. (Reminder: Your fist hold during arm’s length measures about 10 degrees.)
During a final week of August, Comet Swift-Tuttle developed into a strikingly pleasing object, apropos scarcely as splendid as Polaris and sporting an commanding tail that was about 30 degrees long. And by telescopes, observers saw radiant jets and fountains nearby a nucleus. During a following weeks, Swift-Tuttle fast faded, and by a commencement of October, a southward transformation precluded serve observations from a United States.
Several important astronomers attempted to calculate an circuit for a comet regulating scores of positional measurements, and a ubiquitous accord was that it was roving in a really elongated circuit with a duration of roughly 120 years.
At about a same time, Giovanni Schiaparelli of Italy began questioning a circuit of a Perseids and found that a orbital elements of a comet and a meteors were most identical. It therefore became transparent that waste strew from Comet Swift-Tuttle was a source of St. Lawrence’s burning tears: a Perseid meteor shower!
These little cometary fragments — large pieces of steel and mill — are called meteoroids while they journey by space. They turn meteors when they strike Earth’s atmosphere. The strain of light we call a “shooting” or “falling” star is constructed by a atmosphere surrounding a meteor, that is exhilarated to incandescence by a object’s thrust by a air.
Just as Comet Swift-Tuttle is a progenitor of a Perseids, a waste of other comets generates other meteor showers. (Halley’s Comet, for example, is obliged for dual annual showers — the April-May Eta Aquarids and a Oct Orionids.)
Comet Swift-Tuttle was due to lapse to a closeness of a object in 1981 or 1982, yet unsuccessful to appear. About a decade earlier, however, astronomer Brian Marsden, of a Harvard-Smithsonian Center for Astrophysics, had suggested that Swift-Tuttle competence be a same comet that was reported in 1737 by a Jesuit companion in Beijing named Ignatius Kegler.
The tie was probable if “nongravitational” army — those radiant jets on a comet, caused by ice branch into gas since of a sun’s feverishness — exploded out from a comet’s aspect and acted like rocket exhaust, somewhat altering a circuit and negligence a comet down. Dr. Marsden insincere that, with a duration of about 130 years — not a 120 years that was creatively distributed — Comet Swift-Tuttle would lapse during a finish of 1992. [Perseid Meteor Shower: Amazing Photos by Stargazers]
In a years surrounding a comet’s lapse in 1992, a Perseids were distant some-more heated than their common 60 meteors per hour, instead producing brief bursts of adult to several hundred per hour, many of that were dazzlingly splendid and spectacular. This swell expected occurred since Swift-Tuttle’s lapse to a middle solar complement left some-more waste in Earth’s path, researchers have said.
More good things on a way?
Even yet Swift-Tuttle is now distant behind out in space, Perseid activity can still spasmodic jar upward. This year, it’s hoped that a gravitational support from Jupiter will pull a Perseid tide scarcely 1 million miles (1.6 million kilometers) closer to Earth’s circuit and outcome in a much-better-than-average display.
There’s also a possibility of a brief detonate of activity that competence be caused by Earth’s communication with a thick cluster of waste strew by a comet behind in 1079. From a clear, dark, nonlight-polluted plcae — and after a moon sets early on a morning of Aug. 12 — meteor rates in additional of 150 per hour this year seem possible.
And a obvious Finnish meteor consultant suggests that a Perseids might yield an even larger uncover in years to come. Esko Lyytinen has distributed that a showering could furnish 1,000 or some-more meteors per hour in 2028, as Earth passes within 37,000 miles (59,500 km) of a tide of waste that Swift-Tuttle expelled into space behind in 1479.
Another meteor researcher, Mikhail Maslov from Russia, also expects that a meteor charge will start in 2028. But his calculations advise a some-more medium one, of maybe 250 to 300 meteors per hour. [Top 10 Perseid Meteor Shower Facts]
Because Comet Swift-Tuttle passes really tighten to Earth’s orbit, there have always been concerns that it could one day hit with Earth.
In 1992, Marsden looked into a subsequent lapse of Swift-Tuttle in 2126, warning that, if a tangible date of a comet’s closest proceed to a object was off by 15 days from his prophecy of Aug. 14 (his 1992 prophecy had been off by 17 days), a collision would be possible. Later, however, he was means to labour calculations of a comet’s circuit accurately adequate to comment for a comet’s position in space going behind scarcely 2,000 years; when he afterwards looked forward to 2126, he found that Swift-Tuttle would skip Earth by during slightest 15 million miles (24 million km).
Potential disaster averted.
However, looking even serve ahead, Marsden found that, in Aug 3044, Swift-Tuttle will come within usually about 1 million miles (1.6 million km) of Earth. By vast standards, that’s a precariously tighten trim — especially deliberation that, during 16 miles (26 km) wide, a comet is a large one.
Editor’s note: If we have an extraordinary print of this year’s Perseid meteor showering you’d like to share for a probable story or picture gallery, greatfully hit handling editor Tariq Malik at firstname.lastname@example.org.
Joe Rao serves as an instructor and guest techer during New York’s Hayden Planetarium. He writes about astronomy for Natural History magazine, a Farmer’s Almanac and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.