Earth will experience one of the closest approaches by a comet in recorded history next week as two comets closely pass by, according to NASA scientists. Comet 252P/LINEAR, an emerald-green space body about 750 feet across, discovered on April 7, 2000 by researchers at MIT’s Lincoln Near-Earth Asteroid Research (LINEAR), will pass “remarkably close” to Earth on Monday, March 21, at about 5:14 a.m.(PDT), at a distance of about 3.3 million miles.
Comet 252P will be followed the next day by its “close twin” Comet PanSTARRS or P/2016 BA14, about half the size of 252P.
P/2016 BA14 will pass even closer to Earth on Tuesday, March 22, at about 7:30 a.m.(PDT), at a distance of about 2.2 million miles.
The approach of comet P/2016 BA14, according to astronomers, is the third closest in the recorded history of comet flybys and the closest in nearly 250 years.
P/2016 BA14 was discovered on January 21/22, 2016 by astronomers using the University of Hawaii’s PanSTARRS 1 telescope on the island of Maui.
Only two other comets are known to have come closer to Earth in recorded history. They are 55P/Tempel-Tuttle, believed to have passed at a distance of 2.1 million miles on October 26, 1366, and Lexell’s comet (D/1770 L1), which passed on July 1, 1770 and missed Earth by only 1.4 million miles.
Comet IRAS-Araki-Alcock (C/1983 H1) passed by in 1983, but was farther away, at a distance of 2.9 million miles.
P/2016 BA14 was thought initially to be an asteroid but it was later reclassified as a comet when astronomers at the University of Maryland and Lowell Observatory, using the Discovery Channel Telescope, observed it had a faint tail.
Due to P/2016 BA14’s strikingly similar orbit to 252P/LINEAR — a period of 5.32 for 252P/LINEAR and 5.25 for P/2016 BA14 — some astronomers believe that both comets have a common origin and that BA14 may have broken from the larger 252P in the past, for instance, during a previous flyby of the giant planet Jupiter or during a previous passage through the inner solar system, according to Paul Chodas, at the NASA Jet Propulsion Laboratory’s (JPL) Center of NEO Studies (CNEOS) in Pasadena, California.
“We know comets are relatively fragile things, as in 1993 when comet Shoemaker-Levy 9 was discovered and its pieces linked to a flyby of Jupiter,” Chodas said. “Perhaps during a previous pass through the inner-solar system or during a distant flyby of Jupiter, a chunk that we now know of as BA14 might have broken off of 252P.”
But further studies are needed to confirm the theory that BA14 broke off from 252P, astronomers say. And if the studies confirm the hypothesis, the comets will provide a rare opportunity to study comets formed through breaking up of larger ones.
According to the University of Maryland’s Matthew Knight, who was part of the team that first detected that P/2016 BA14 has a tail and thus that it is a comet, “Comets split relatively often, but we rarely get a chance to study them soon after it happens, and when we do usually only the bigger fragment survives. We have two fragments in this case.”
Astronomers say that 252P will be visible on Monday to the naked eye in southern hemisphere suburbs where light pollution in low, but sky watchers in the U.S. would likely need binoculars to observe it.
All sky-watchers will need a telescope to observe BA14 as it passes from Canis Major to Ursa Major over a period of seven days, Sky and Telescope reports.
Astronomers will monitor the close passage of the two comets using the Hubble Space Telescope and the ground-based Gemini telescopes consisting of twin 8.1-meter diameter optical-infrared telescopes in Hawaii and Chile.
Although the passage of the comets is “remarkably close” on the astronomical scale of events, scientists assure that they pose no threat to Earth and will fly by Earth safely.
“Comet P/2016 BA14 is not a threat,” Chodas said. “Instead, it is an excellent opportunity for scientific advancement on the study of comets.”
According to Chodas, it is unlikely that we will witness such a close comet flyby in the next 150 years.
“March 22 will be the closest comet P/2016 BA14 gets to us for at least the next 150 years.”
“March 22 will be the closest comet P/2016 BA14 gets to us for at least the next 150 years,” he said.
Michael Kelley of the University of Maryland said, “This is one for the record books. It’s a fantastic opportunity for professionals to learn more about comets, and if you have a chance to try to find them… it’s a fantastic chance to see part of history as it happens.”
[Image via NASA]