Comets

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Miserable comet ends life by diving into the Sun (VIDEO)

sundiving comet
© SOHO
Perhaps upset that it's so hard to find a mate in the unimaginable barrenness of space, a lone comet wandered into the Sun yesterday and has not been seen since. (Follow the jump for multiple angles of its fiery demise.)

The deceased likely belonged to the suicidally depressed Kreutz comet family. Astronomer Heinrich Kreutz theorized in 1888 that many sun-diving comets were once part of a larger, cohesive comet up to 66 miles wide that separated in a traumatic breakup centuries ago. Now the Kreutzian children rove the solar system, flirting with annihilation by buzzing the scalding zone around the sun.

A few, like the 1882 "Super Comet" and 1965's Ikeya - Seki, obtain lasting glory by lighting up like a disco ball in hell, a spectacle visible from Earth during the daytime. But most are silently consumed by the furious and insatiable Sun, a steady procession of cosmic nullifications ignored by the average human. Astronomers estimate that the solar system harbors more than 1,600 comets with paths perilously close to the solar touch of death.

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Another Sundiving Comet

Today, the solar system has one less comet. During the late hours of July 5th, an icy unnamed comet dove into the sun and disintegrated. The comet's last hours were recorded by coronagraphs onboard the the Solar and Heliospheric Observatory (SOHO):


The comet was probably a member of the Kreutz sungrazer family. Named after a 19th century German astronomer who studied them in detail, Kreutz sungrazers are fragments from the breakup of a giant comet at least 2000 years ago. Several of these fragments pass by the sun and disintegrate every day. Most are too small to see but occasionally a big fragment like this one attracts attention.

NASA's STEREO-A and -B spacecraft also recorded the event, and they are beaming their data back to Earth now. In a few days we'll have high-res movies of a comet's death plunge from three points of view: SOHO, STEREO-A and STEREO-B. Stay tuned.

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Each June, a giant comet stalks the Earth


Last week the Earth came close to being hit by a chunk of cosmic debris packing the punch of a Hiroshima-type atomic bomb.

The house-sized asteroid 2011 MN shot past the Earth at more than 25,000kph last Monday, coming closer than some communications satellites before flying off back into the void of space.

So why were we not warned? One reason was that although it was a close-run thing, astronomers had pinned down the path of 2011 MN well enough to be pretty confident it would miss us.

Another was that even if it had struck, it would have lost most of its energy as it entered our atmosphere, most likely burning up to give a brief but impressive shower of "shooting stars".

Binoculars

US - July 3, 1861: The Great Comet - what does it portend?

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© Cometography.comThe Great Comet of 1861 passed closest to Earth on June 30, 1861.
"The Comet. Mr. Editor: -- Did you see the comet Monday night? I was indebted for the pleasure to an excellent friend, who took the trouble to call and awaken me. I certainly was never more astonished. All similar visitors to our system have either been foretold, or discovered by astronomers when not visible to the naked eye. Their approach has been gradual, and their advent and progress duly chronicled by the newspapers. But this has come like a thief in the night, unannounced - - undiscovered -- until, with a splendor far beyond any of its predecessors, it blazes in our firmament ... The tail reached the zenith, inclining a little to the West. The body seemed three or four times as large as that of any other comet I ever saw. My friend says when it first caught his eye, without referring to the points of the compass, he took it for the moon ..."

Letter to the editor, The Daily Virginian

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Best of the Web: When Comets Attack: Solving the Mystery of the Biggest Natural Explosion in Modern History

Comet
© Pete Turner/Getty Images
On the morning of June 30, 1908, the sky exploded over a remote region of central Siberia. A fireball as powerful as hundreds of Hiroshima atomic blasts scorched through the upper atmosphere "as if there was a second sun," according to one eyewitness. Scientists today think a small fragment of a comet or asteroid caused the "Tunguska event," so named for the Tunguska river nearby. No one knows for certain, however, because no fragment of the meteoroid has ever been found. The explosion was so vast - flattening and incinerating over an 800 square-mile swath of trees - that generations of amateur sleuths have put forward scenarios as strange as stray black holes or UFO attacks to explain the tremendous explosion.

Now, a controversial scientific study suggests that a chunk of a comet caused the 5 to 10 megaton fireball - what amounts to the largest non-nuclear explosion in modern history. Crucially, according to the new hypothesis, most of the comet bounced off the atmosphere and back into orbit around the sun. The scientists have even identified a candidate Tunguska object - now more than 100 million miles away - that was somewhere near Earth on June 30, 1908 and will be passing close to Earth again in 2045. But just how could a comet - basically a ball of water ice and cosmic dust - create such a massive explosion and leave no trace? The answer, the scientists believe, can be found in basic chemistry rather than complicated physics or evidence yet to be found.

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Best of the Web: Space shuttle science shows how 1908 Tunguska explosion was caused by a comet

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© WikimediaTrees were levelled in Siberia after what is thought to have been an impact from space in 1908
The mysterious 1908 Tunguska explosion that leveled 830 square miles of Siberian forest was almost certainly caused by a comet entering the Earth's atmosphere, says new Cornell University research. The conclusion is supported by an unlikely source: the exhaust plume from the NASA space shuttle launched a century later.

The research, accepted for publication (June 24, 2009) by the journal Geophysical Research Letters, published by the American Geophysical Union, connects the two events by what followed each about a day later: brilliant, night-visible clouds, or noctilucent clouds, that are made up of ice particles and only form at very high altitudes and in extremely cold temperatures.

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Past Due? On an Average of Every One Million Years, Earth Absorbs a Major Asteroid or Comet Impact

Object In Sky
© Daily Galaxy

A house-sized asteroid zipped apst Earth yesteday closer than the moon. Stephen Hawking believes that one of the major factors in the possible scarcity of intelligent life in our galaxy is the high probability of an asteroid or comet colliding with inhabited planets. Through Earth's history such collisions occur, on the average every one million years. If this figure is correct, it would mean that intelligent life on Earth has developed only because of the lucky chance that there have been no major collisions in the last 70 million years. Other planets in the galaxy, Hawking believes, on which life has developed, may not have had a long enough collision free period to evolve intelligent beings.

We have observed, Hawking points out in Life in the Universe, the collision of a comet, Schumacher-Levi, with Jupiter, which produced a series of enormous fireballs, plumes many thousands of kilometers high, hot "bubbles" of gas in the atmosphere, and large dark "scars" on the atmosphere which had lifetimes on the order of weeks.

It is thought the collision of a rather smaller body with the Earth, about 70 million years ago, was responsible for the extinction of the dinosaurs. A few small early mammals survived, but anything as large as a human, would have almost certainly been wiped out.

"The threat of the Earth being hit by an asteroid is increasingly being accepted as the single greatest natural disaster hazard faced by humanity," according to Nick Bailey of the University of Southampton's School of Engineering Sciences team, who has developed a threat identifying program.

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And Yet Another One: Newfound Comet Will Swing By Earth in 2013

comet C/2011 L4
© Institute for Astronomy/University of Hawaii/Pan-STARRSDiscovery image of the newfound comet C/2011 L4 (PANSTARRS), taken by Hawaii's Pan-STARRS 1 telescope.
A newfound comet discovered by a telescope designed to hunt for dangerous asteroids will make its closest pass by Earth in 2013 and should be visible to the naked eye when it draws near, astronomers say.

Hawaii's Pan-STARRS 1 telescope detected the comet, which is called C/2011 L4 (PANSTARRS), on the night of June 5 and 6, and the discovery was confirmed by follow-up observations with a different instrument a day later. The comet will likely come within about 30 million miles (50 million kilometers) of the sun in February or March 2013 - about the same distance as the planet Mercury, researchers said.

During its closest approach to Earth in two years, comet C/2011 L4 (PANSTARRS) likely to be visible low in the western sky shortly after sunset, weather permitting. Skywatchers interested in seeing the newfound icy wanderer should look up then, because they may never get another chance to see it.

"The comet has an orbit that is close to parabolic, meaning that this may be the first time it will ever come close to the sun, and that it may never return," said the University of Hawaii's Richard Wainscoat in a statement. Wainscoat helped confirm the comet's existence.

Right now, C/2011 L4 (PANSTARRS) is about 700 million miles (1.2 billion km) from the sun, placing it beyond the orbit of Jupiter. It is currently so faint that only telescopes with sensitive electronic detectors can pick it up.

The comet's clunky moniker is slightly unusual. Comets are usually named after their discoverers, but in this case such a large team of researchers helped spot the icy wanderer that it took the name of the telescope instead.

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Quirky Comet Hartley 2 Confounds Theories on Early Solar System

comet hartley 2
© NASA/JPL-Caltech/UMDThis close-up view of comet Hartley 2 was taken by NASA's EPOXI mission during its flyby of the comet on Nov. 4, 2010. It was captured by the spacecraft's Medium-Resolution Instrument.
The small Comet Hartley 2 is an oddball, for sure.

Two craggy bulges connected by a smooth waist (somewhat like a peanut), Comet Hartley 2 spews out more material than a comet just under a mile wide is expected to, a new study finds. And while most comets rotate slowly in one direction, Hartley spins rapidly as it tumbles.

Furthermore, Hartley 2 contains an inexplicable amount of carbon dioxide, causing it to burp and even hock ice loogies into space.

The unusual comet is raising questions over some longtime assumptions by scientists on how comets formed in the early solar system, said the scientists involved in the new study. [Photos: Close-Up Views of Comet Hartley 2]

The new Hartley 2 discoveries are based on the latest analysis of observations collected during a November 2010 flyby of the comet by NASA's Deep Impact spacecraft as part of its Extrasolar Planet Observation and Deep Impact Extended Investigation (EPOXI) mission. During the flyby, the Deep Impact probe approached within 431 miles (694 km) of the comet, snapping photos all the way.

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You'll be able to see comet just discovered by University of Hawaii astronomers

Astronomers at the University of Hawaii at Manoa have discovered a new comet that they expect will be visible to the naked eye in early 2013.

Originally found by the Pan-STARRS 1 telescope on Haleakala, Maui, on the night of June 5-6, it was confirmed to be a comet by UH astronomer Richard Wainscoat and graduate student Marco Micheli the following night using the Canada-France-Hawaii Telescope on Mauna Kea.
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© University of Hawaii C/2011 L4

A preliminary orbit computed by the Minor Planet Center in Cambridge, Mass., shows that the comet will come within about 30 million miles of the sun in early 2013, about the same distance as Mercury. The comet will pose no danger to Earth.

Wainscoat said, "The comet has an orbit that is close to parabolic, meaning that this may be the first time it will ever come close to the sun, and that it may never return."

The comet is now about 700 million miles from the sun, placing it beyond the orbit of Jupiter. It is currently too faint to be seen without a telescope with a sensitive electronic detector.