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Stony Brook professor tracks comet

Stony Brook University Astronomer and Professor Jin Koda

Stony Brook University Astronomer and Professor Jin Koda poses with a telescope at the university's observatory. Koda recently led a team of astronomers who captured an image of the intricate flow of the ion tail of Comet Lovejoy. (Dec. 9, 2013; Dec. 3, 2013) Credit: Newsday / John Paraskevas, Handout

Comet chaser Jin Koda journeyed to one of Earth's loftiest summits to view a cosmic phenomenon as it streaked toward its destiny -- a fast-moving comet en route to circle the sun.

"We used the largest telescope in the world," said Koda, an assistant professor of astrophysics at Stony Brook University, referring to the gargantuan Subaru Telescope. It's situated atop Hawaii's dormant volcano, Mauna Kea, 13,803 feet above sea level.

The air was so thin, Koda said, that he had to adapt to the atmospherics before embarking on his sky search.

He's conducting a series of intricate studies of Comet Lovejoy, a 6-mile-wide ball of ice and dirt hurtling toward a close encounter with the sun.

Koda recently led an international group of scientists who also tracked Lovejoy, a comet so large that it's visible with binoculars, appearing as a bright starlike object with a cloudy tail. Perhaps more intriguing, it can be seen from perches far less elevated than Mauna Kea.


300 miles per second

If you don't have interference from city lights, and don't mind searching a darkened sky just before dawn, you can catch a good view of Lovejoy, Koda said.

"It will be in the eastern side of the sky. So look toward the horizon and you can see it.

"The comet is moving," he continued, "but when you look at it with binoculars, you will not see any motion."

Lovejoy, which is traveling about 300 miles per second, will be visible until the end of the month, according to Koda's calculations.

"It's like a Christmas present," he said.

Comets revolve around the sun in elliptical -- egg-shaped -- orbits that can take decades or millions of years.

Halley's comet, one of the most famous, is a so-called short-period comet, Koda said, which means it makes its way back into the solar system every 75 or so years in its trip around the sun. It was last seen on Feb. 9, 1986, and is expected to return on July 28, 2061. No one yet knows what Lovejoy's periodicity will be.

Comets are often born in the deepest and most frigid regions of the solar system, the galactic outskirts near ex-planet Pluto.

Distant and dark, Pluto's neighborhood -- the Kuiper belt -- is one of the richest cosmic regions for the emergence of comets. Halley's comet was born in the Kuiper belt, space scientists say.

Yet another vast -- but poorly understood -- region is the all-encompassing Oort cloud, which astronomers believe surrounds the solar system and exists beyond our sun's influence.

From the Oort cloud emerge comets with long periodicities. They may take thousands, even millions of years to orbit the sun.

No matter where they're born, comets are amalgamations of water-ice, frozen gases of methane and carbon dioxide, rock and cosmic dust.

Their tails are "sublimed" vapors of gases as well as particles -- space dust -- that moves off the core as it's buffeted by solar winds.

"All comets come from way out in cold storage," said Denton Ebel, curator and division chair of Earth and Planetary Science at the American Museum of Natural History in Manhattan.

"In the past we thought of comets as dirty snowballs, but many of us now think of them as snowy dirtballs. There is quite a bit of stuff in them," Ebel said.


Citizen scientists

NASA's Stardust mission in 2006 captured and returned to Earth unprecedented cometary samples that the museum is still studying.

Capturing comet particles wasn't easy, NASA scientists say, because the space dust was traveling at six times the speed of a rifle bullet.

"The tiny particle grains are the same kind you find in meteorites," Ebel said.

Comet Lovejoy was discovered by a citizen scientist, Terry Lovejoy, an Australian who has found other comets that also bear his name.

Asked why an amateur beat university astrophysicists to the discovery, Koda noted that citizen scientists are constantly scanning the night sky for moving objects and have become adept at finding comets.

Comet Hale-Bopp of the 1990s was discovered by two citizen scientists. A do-it-your-selfer found the equally famous Comet Kohoutek in the 1970s. Kohoutek is believed to be a long-period comet, which means it makes a near-Earth appearance every 150,000 years.

Ebel noted that citizen scientists have added tremendously to the body of knowledge about comets, helping to peel away much of their mystery.

"A lot of great work is done by citizen scientists," Ebel said. "I never refer to them as amateurs."

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