According to astronomers, a three-mile-diameter object is making a “near” approach in December, passing within 6.4 million miles of Earth. That’s 27 times the distance from the Earth to the moon.
The object, asteroid 3200 Phaethon, at its closest on Dec. 16, is expected to come even closer in 2093—1.8 million miles.
Though the International Astronomical Union’s Minor Planet Center calls it “potentially dangerous,” astronomers are used to dealing with enormous spans of time and space. According to CBS News space consultant Bill Harwood, there is almost no situation in any foreseeable future where asteroid 3200 Phaethon will collide with the planet Earth.
“Any body that’s bigger than about 500 feet across and its orbit carries it within about 4.6 million miles of Earth at any point in its orbit is classified as a ‘potentially hazardous’ object,” he explained.
“Meaning over millennia—lots and lots of time—gravitational interactions with the outer planets, you know, other objects in the solar system might perturb the orbit enough that it could actually impact the Earth.”
“Now in the case of this asteroid, that’s not the case,” he concluded. “They think this asteroid—and its orbit is very well known—will never get closer than about 1.8 million miles of the Earth.”
Even at 6.4 million miles, 3200 Phaethon should be visible to people with access to small telescopes when it makes its closest approach on Dec. 16, according to Michael Mendillo, a professor of astronomy at Boston University.
Benefit of Near Approach
Citizens of Earth—enjoy your light show! The coming of 3200 Phaethon heralds the arrival of the Geminids meteor shower, which will light up the night skies in mid-December, peaking on the night of Dec. 13 and the morning of Dec. 14 with about 120 objects per hour, according to Space.com.
Most meteor showers are caused by comets—basically, ice-balls with rocks and dust stuck to it. The Gemenid shower is unusual because it comes from an asteroid.
The Gemenid shower is also unusual because it is extremely recent—in astronomical terms.
The first recorded observation of the shower was in 1833 from a riverboat on the Mississippi River, Space.com reports.
According to NASA’s Bill Cook, it is likely that 3200 Phaethon collided with another chunk of rock a few centuries ago, and over time, Jupiter’s gravitational field pulled the resulting debris into the path of Earth’s orbit.
Not all scientists are certain that 3200 Phaethon collided with another orbiting object hundreds of years ago. A paper published in 2013 in the Astrophysical Journal Letters says that, based on three years of observations from NASA’s STEREO spacecraft, when 3200 Phaethon gets close to the Sun, the heat or solar wind breaks off portions of the rock.
3200 Phaethon gets closer to the Sun than any other named orbiting body, sometimes coming as close as 17 million miles—half the distance from the Sun to the planet Mercury. It’s surface temperature reaches 1,200 degrees Fahrenheit, according to Sky and Telescope.
Scientists discovered in 2013 that 3200 Phaethon has a tail like a comet—but comet tails are produced by ice turning to gas. 3200 Phaethon’s tail seems to be dust pulled off by the Sun’s heat and gravitational field.
If 3200 Phaethon is composed of carbonaceous materials—compounds containing a lot of water and carbon—the compounds might get brittle in the extreme heat and break apart when tugged one way by the Sun and another way by momentum.
“Phaethon may be a breakup in slow motion,” Paul Wiegert, an astronomer at the University of Western Ontario in Canada, said at the Division of Planetary Sciences meeting in Pasadena, California.
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