Comets


Telescope

Ice Age Ends Smashingly: Did a comet blow up over eastern Canada?

Evidence unearthed at more than two dozen sites across North America suggests that an extraterrestrial object exploded in Earth's atmosphere above Canada about 12,900 years ago, just as the climate was warming at the end of the last ice age. The explosion sparked immense wildfires, devastated North America's ecosystems and prehistoric cultures, and triggered a millennium-long cold spell, scientists say.

Meteor

Observations of a very bright fireball and its likely link with comet C/1919

 Bejar bolide
© J. Perez Vallejo/SPMN)A close-up image of the Bejar bolide, photographed from Torrelodones, Madrid, Spain.

Last July, people in Spain, Portugal and France watched the brilliant fireball produced by a boulder crashing down through the Earth's atmosphere. In a paper to be published in the journal Monthly Notices of the Royal Astronomical Society, astronomers Josep M. Trigo-Rodríguez (Institute of Space Sciences, CSIC-IEEC, Spain), José M. Madiedo (University of Huelva-CIECEM, Spain) and Iwan P. Williams (Queen Mary, University of London) present dramatic images of this event.

The scientists go on to explain how the boulder may originate from a comet which broke up nearly 90 years ago and suggest the tantalising possibility that chunks of the boulder (and hence pieces of the comet) are waiting to be found on the ground.

Telescope

Comet Lulin Update

Image
© Gregg Ruppel Comet Lulin passing just north of the bright star Zubenelgenubi (alpha2 Librae) on 2/6/09

Comet Lulin (C/2007 N3) is approaching Earth for a 38-million-mile close encounter on Feb. 24, 2009. At the moment it is glowing like a 6th magnitude star, dimly visible to the unaided eye and a fine target for binoculars and backyard telescopes.

Comet Lulin is now visible to the naked eye from dark-sky sites. "This morning, Feb 6th, I noticed a faint smudge above Zubenelgenubi," reports Jeff Barton from the Comanche Springs Astronomy Campus in West Texas. "I then trained my 9x63 binoculars on the fuzzy patch. Yep, nailed it! I was thrilled to finally bag Comet Lulin without optical aid."

Meteor

'Comets Responsible for Originating Life on Earth'

There is growing evidence that life on earth has come from the universe through comets, an eminent British scientist said here.

"Life is cosmically abundant and was brought to the earth by comets and our genes and those of all living forms on earth were brought by comets, neatly-packaged within cosmic microorganisms," professor N Chandra Wickramasinghe, Director, Cardiff Centre for Atrobiology, Cardiff University, said.

The astrobiologist speaking at Nehru Planetarium said, "Our genetic ancestors still lurk amidst the stars, and molecular biology is being deployed to trace connections between different species in search of a Last Universal Common Ancestor (LUCA) for all life on the Earth."

Meteor

Comet Lulin's Disconnected Tail

Lulin
© Ernesto Guido, Giovanni Sostero & Paul Camilleri

On Feb. 4th, a team of Italian astronomers witnessed "an intriguing phenomenon in Comet Lulin's tail." Team leader Ernesto Guido explains: "We photographed the comet using a remotely-controlled telescope in New Mexico, and our images clearly showed a disconnection event. While we were looking, part of the comet's plasma tail was torn away."

Meteor

Did a comet strike Earth, leaving crystalline dust in the Oklahoma Panhandle?

A giant comet slammed into the atmosphere and fractured. The resulting swarm of fragments also exploded, scattering tiny diamonds in widely separated locations and plunging the warming Earth into a renewed and deadly deep freeze.

When Leland Bement first heard the theory, "I was highly skeptical," he said. "You just roll your eyes."

But a discovery in the Oklahoma Panhandle changed his viewpoint. It began when Bement, research archaeologist with the Oklahoma Archaeological Survey, was contacted by a team of scientists who had read about Bement's research. For years, Bement had been studying remnants of Indian communities that existed around the end of the last Ice Age - about 13,000 years ago - in the area that is now the Panhandle.

Meteor

Where Do Comets Come From?

Comet Overhead
© Walter Pacholka, Astropics/SPLHale-Bopp, seen here from Joshua Tree National Park, California, was one of the brightest comets of the 20th century.
Few cosmic apparitions have inspired such awe and fear as comets. The particularly eye-catching Halley's comet, which last appeared in the inner solar system in 1986, pops up in the Talmud as "a star which appears once in seventy years that makes the captains of the ships err". In 1066, the comet's appearance was seen as a portent of doom before the Battle of Hastings; in 1456, Pope Callixtus III is said to have excommunicated it.

Modern science takes a more measured view. Comets such as Halley's are agglomerations of dust and ice that orbit the sun on highly elliptical paths, acquiring their spectacular tails in the headwind of charged particles streaming from the sun. We even know their source: they are Kuiper belt objects (KBOs) tugged from their regular orbits by Neptune and Uranus.

But there's a problem. Certain comets, such as Hale-Bopp, which flashed past Earth in 1997, appear simply too infrequently in our skies. Their orbits must be very long, far too long to have an origin in the Kuiper belt. The conclusion of many astronomers is that the known solar system is surrounded in all directions by a tenuous halo of icy outcasts, thrown from the sun's immediate vicinity billions of years ago by the gravity of the giant planets.

Meteor

New comet may be visible with the naked eye

comet lulin
© Giovanni Sostero and Ernesto Guido, Remanzacco ObservatoryComet Lulin as seen on 2 January 2009. The image shows both the tail and the anti-tail.

Late next month Earth will receive a new celestial visitor named Lulin - or Comet C/2007 N3 - which astronomers say may have never visited this corner of the solar system before and should be visible to the naked eye.

Comets are icy clumps of dust and small rocks left over from the beginnings of the solar system. As they near the Sun some of the outer layer of ice is vaporised, releasing gas and solid debris that fans out into a tail pointing directly away from the Sun.

Astronomer and author Gary Kronk, based in St Jacob, Illinois, estimates that by 24 February, Lulin's gas tail should appear as long as around eight times the diameter of a full Moon. At that time it will be a mere 38 million miles from Earth, almost as close as Mars reaches to our planet.

Meteor

Mammoth-Killing Comet Questioned

mammoths
© BBC NewsWoolly mammoths were not the only ones to die out 13,000 years ago.
A study of wildfires after the last ice age has cast doubt on the theory that a giant comet impact wiped out woolly mammoths and prehistoric humans.

Analysis of charcoal and pollen records from around 13,000 years ago showed no evidence of continental-scale fires the cometary impact theory suggests.

However, the results showed increased fires after periods of climate change.

Telescope

Italian spots new comet

Halley's comet
© UnknownHalley's Comet
Rome - An Italian astronomer has kept up an amazing spotting streak with his ninth comet in just over a year.

Andrea Boattini, who broke the 150-year-old Italian record for comet spotting with seven last year, said he spotted the new body in the early hours of the night while he was scanning all the Near Earth Objects (NEOs) currently visible.

''I wasn't too sure it was a comet straight away because it was hazy but the skies cleared a bit later and allowed me to confirm the comet's nature,'' said Boattini, 39, who works at the Mount Lemmon Observatory in Arizona on a NASA programme to identify objects that could potentially pose a threat to the Earth.