Three-mile-wide asteroid will pass close to Earth in mid-December

Astronomers will closely study the object, which is still not well understood.
By Laurel Kornfeld | Nov 28, 2017
A three-mile- (five-km-) wide asteroid classified as "potentially hazardous" due to its large size will fly relatively close to Earth next month.

Known as 3200 Phaethon, the asteroid, which orbits the Sun every 1.4 Earth years, will pass within 6.5 million miles of Earth or 27 times the distance between the Earth and Moon, on December 16.

Discovered in 2007 by satellite and about half the size of the asteroid believed to have killed the dinosaurs 65 million years ago, it is also the source of the Geminid meteor shower, which occurs in early to mid-December.

Scientists are unsure as to Phaethon's origin. Most meteor showers come from fragments of comets vaporized as the comets approach the Sun.

Asteroids are thought to be incapable of producing meteor showers, leading some scientists to suspect Phaethon could be a dead comet.

NASA has designated Phaethon as "potentially hazardous" because it has the potential to come close to Earth and would cause significant damage in an impact.

It poses no danger to Earth during next month's approach.

Like most asteroids, it is believed to have originated in the belt between Mars and Jupiter. Over the last several hundred years, Jupiter's gravity has pulled its debris closer to Earth, increasing the brightness of the Geminid meteor shower.

The Geminids will be visible from December 4-17 and will peak December 13-14.

As Phaethon heads in Earth's direction, scientists at NASA's Jet Propulsion Laboratory (JPL) in California plan to create a 3D model of it.

They also hope to identify its composition, which will is key to determining its origin. While asteroids consist primarily of rock and metal, comets are "dirty snowballs" of rock and dust covered with ice.

Russian astronomers are also tracking Phaethon during its close approach and have released a video illustrating its path.

Because Phaethon has showed some sign of activity as it heads in the direction of the Sun, some scientists think it has an inactive cometary nucleus, which they will try to locate as it comes near.

Observers will need a small telescope to see Phaethon, which will be brightest between December 11 and 21.




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