The Chicago Tribune Quotes the C.A Nov 6, 2007 1:21:37 GMT -6
Post by Chicago Astronomer Joe on Nov 6, 2007 1:21:37 GMT -6
This thing of beauty a joy for now
Comet 17P/Holmes sheds its skin and thrills skywatchers
Comet 17P/Holmes sheds its skin and thrills skywatchers
By Ryan Haggerty | Tribune staff reporter
11:43 PM CST, November 5, 2007
A fuzzy light, a tad larger than a star and visible in the northeastern sky even through the haze of light pollution that hangs over Chicago at night, has caused quite a stir among stargazers since its surprise appearance about two weeks ago.
Comet 17P/Holmes, usually fainter than Pluto and largely overlooked by astronomers since its discovery in the late 19th Century, is breaking apart in front of our eyes, emitting an expanding cloud of gas, ice and debris.
"It's literally one of the best things I've seen in the sky, probably in 10 years," said Michael Smutko, a senior lecturer in astronomy at Northwestern University and an astronomer and director of the Doane Observatory at the Adler Planetarium. "The fact that it's right there and you can see it with your naked eye through the lights of Chicago, the fact that it seems to be getting better as the days go by, is really impressive."
Those who gazed at the sky through telescopes during a public viewing session at the Adler Planetarium last week were taken aback by the comet, said Joseph Guzmán, founder of the Chicago Astronomer, an online forum for amateur astronomers.
"They were astounded that you could actually see a comet from downtown Chicago," Guzmán said.
Visible comets are a celestial rarity. Often called "dirty snowballs," comets are made of ice and dust and become visible when they melt and shed debris, which forms their trademark tails.
This comet is different. Comet Holmes was transformed overnight into the superstar of the solar system Oct. 23, when it somehow became unglued. It shed its contents at nearly 1,000 m.p.h. and created a debris cloud that is now almost 100 times the size of Earth, said Mark Hammergren, an astronomer at the Adler.
That debris reflects the sun's light, making it visible to the naked eye.
"Overnight, it exploded in brightness by a factor of about a million," Hammergren said. "The comet just suddenly blew off a shell of gas and dust. It basically lost a good portion of its surface, which blew off into space."
This has happened before.
Comet Holmes was discovered by British astronomer Edwin Holmes on Nov. 6, 1892, when it underwent a similar but smaller outburst.
Astronomers later lost track of the comet until it was rediscovered in the 1960s, orbiting the sun about every seven years without much fanfare on Earth.
Although such outbursts are relatively rare and not completely understood by astronomers, most occur when comets pass close to the sun and are split apart by the hot solar wind, Hammergren said. Comet Holmes' outburst is confounding, however, because it occurred as the comet was moving away from the sun, said Hammergren. He theorized that the comet was spinning at such a rapid rate that it simply broke apart.
"It's extraordinary," Hammergren said. "It's really quite rare to have a comet this far from the sun visible in the middle of the night."
The comet will be visible to the naked eye as a hazy spot throughout the night for at least the next few weeks, appearing in the northeastern sky near the constellation Perseus, Hammergren said. Telescopes reveal the comet's nucleus and debris cloud in greater detail, but the comet's tail is invisible, extended behind the comet and away from Earth, Hammergren said.
Whatever the outburst's cause, the comet has been the talk of astronomy Web sites and message boards since its unexpected arrival.
"It's certainly exciting," said Dean W. Armstrong, a member of the Ryerson Astronomical Society at the University of Chicago. Armstrong heard about the comet via e-mail. "It's much better than your average comet. To be able to see it in the city, to be able to see it with your own eyeballs without going out into the country is wonderful. It gives people a chance to reconnect to the night sky."
Even world-famous astronomers were caught off-guard. Alan Hale, co-discoverer of Comet Hale-Bopp, heard about Comet Holmes from astronomers in Spain and Japan.
"I went out and saw that it was bright enough to see as a naked-eye star," Hale said. "By the time I saw it the next night, it was clearly much brighter than it had been that morning. . . . It's an interesting opportunity to go out and see an unusual member of the solar system."
Where to get a close-up look
November 6, 2007
Although Comet 17P/Holmes is visible to the naked eye, curious stargazers can gather with local amateur and professional astronomers for a high-powered view of the comet over the next few weeks.
Adler Planetarium:Members of the Chicago Astronomer, an online forum for amateur astronomers, gather frequently on the south lawn of the planetarium and share their telescopes and expertise with the public. Check www.chicagoastronomer.com for the time and date of the group's next viewing.
Northwestern University, Evanston campus: Northwestern's Dearborn Observatory is free and open to the public every Friday from 9 to 11 p.m. Reservations are required during the first hour, while the second hour is first-come, first-served. Call 847-491-7650 or visit www.astro.northwestern.edu and click on Observatory.
University of Chicago: The Ryerson Astronomical Society holds public viewings on the roof of the Ryerson Physical Laboratory, 1100 E. 58th St., every Wednesday from 7:30 to 9:30 p.m., weather permitting. Visit astro.uchicago.edu/RAS/ for details.
Very good article on Chicago based observation of the comet...