Comets


Blackbox

Best of the Web: Massive dark object 'lurking on edge of solar system hurling comets at Earth'

solar system/oort cloud
© Donald K. Yeoman/NASA, JPLA Nasa graphic which illustrates how the Oort Cloud surrounds our solar system. Scientists believe that an object with a huge mass may be pushing comets towards Earth from the cloud
A massive dark object may be lurking on the edge of our solar system, according to scientists.

Most comets that fly into the inner solar system seem to come from the outer region of the Oort cloud - a region of icy dust and debris left over from the birth of the solar system.

The cloud starts from a point about 93 billion miles from the Sun and stretches for around three light years and contains billions of comets, most of them small and hidden.

Now new calculations suggest a large object that is up to four times as big as Jupiter could be responsible for sending them in our direction.

The scientists have analysed the comets in the Oort cloud and deduced that 25 per-cent of them would need a nudge by a body of at least Jupiter size before they changed orbit.

Astrophysicists John Matese and Daniel Whitmire at the University of Louisiana came up with theory said that "something smaller than a Jovian mass would not be strong enough to perform the task".

Meteor

Giant Stealth Planet May Explain Rain of Comets from Solar System's Edge

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Our sun may have a companion that disturbs comets from the edge of the solar system - a giant planet with up to four times the mass of Jupiter, researchers suggest.

A NASA space telescope launched last year may soon detect such a stealth companion to our sun, if it actually exists, in the distant icy realm of the comet-birthing Oort cloud, which surrounds our solar system with billions of icy objects.

The potential jumbo Jupiter would likely be a world so frigid it is difficult to spot, researchers said. It could be found up to 30,000 astronomical units from the sun. One AU is the distance between the Earth and the sun, about 93 million miles (150 million km).

Comment: See: Something Wicked This Way Comes


Sun

The Sun Steals Comets from Other Stars

The next time you thrill at the sight of a comet blazing across the night sky, consider this: it's a stolen pleasure. You're enjoying the spectacle at the expense of a distant star.

Orion Nebula
© NASAA cluster of stars forming in the Orion nebula. According to Hal Levison's research, these stars could be swapping comets.
Sophisticated computer simulations run by researchers at the Southwest Research Institute (SWRI) have exposed the crime.

"If the results are right, our Sun snatched comets from neighboring stars' back yards," says SWRI scientist Hal Levison. And he believes this kind of thievery accounts for most of the comets in the Oort Cloud at the edge of our solar system.

"We know that stars form in clusters. The Sun was born within a huge community of other stars that formed in the same gas cloud. In that birth cluster, the stars were close enough together to pull comets away from each other via gravity. It's like neighborhood children playing in each others' back yards. It's hard to imagine it not happening."

According to this "thief" model, comets accompanied the nearest star when the birth cluster blew apart. The Sun made off with quite a treasure - the Oort Cloud, which was swarming with comets from all over the "neighborhood."

The Oort cloud is an immense cloud of comets orbiting the Sun far beyond Pluto. It is named after mid-20th century Dutch astronomer Jan Oort, who first proposed such a cloud to explain the origin of comets sometimes seen falling into the inner solar system. Although no confirmed direct observations of the Oort cloud have been made, most astronomers believe that it is the source of all long-period and Halley-type comets.

Telescope

Spacecraft Flew Through 'Snowstorm' on Encounter with Comet Hartley 2

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© Unknown
College Park. -- On its recent trip by comet Hartley 2, the Deep Impact spacecraft took the first pictures of, and flew through, a storm of fluffy particles of water ice being spewed out by carbon dioxide jets coming from the rough ends of the comet. The resulting images and data shed new light on the nature and composition of comets, according to the University of Maryland-led EPOXI science team, which today announced its latest findings and released the first images of this comet created snowstorm.

Meteor

Comet Snowstorm Engulfs Hartley 2

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© Deep Impact, NASAThis contrast-enhanced image obtained during Deep Impact's Nov. 4th flyby of Comet Hartley 2 reveals a cloud of icy particles surrounding the comet's active nucleus.
NASA has just issued a travel advisory for spacecraft: Watch out for Comet Hartley 2, it is experiencing a significant winter snowstorm.

Deep Impact photographed the unexpected tempest when it flew past the comet's nucleus on Nov. 4th at a distance of only 700 km (435 miles). At first, researchers only noticed the comet's hyperactive jets. The icy nucleus is studded with them, flamboyantly spewing carbon dioxide from dozens of sites. A closer look revealed an even greater marvel, however. The space around the comet's core is glistening with chunks of ice and snow, some of them possibly as large as a basketball.

"We've never seen anything like this before," says University of Maryland professor Mike A'Hearn, principal investigator of Deep Impact's EPOXI mission. "It really took us by surprise."

Before the flyby of Hartley 2, international spacecraft visited four other comet cores - Halley, Borrelly, Wild 2, and Tempel 1. None was surrounded by "comet snow." Tempel 1 is particularly telling because Deep Impact itself performed the flyby. The very same high resolution, high dynamic range cameras that recorded snow-chunks swirling around Hartley 2 did not detect anything similar around Tempel 1.

"This is a genuinely new phenomenon," says science team member Jessica Sunshine of the University of Maryland. "Comet Hartley 2 is not like the other comets we've visited."

Info

Another Doomed Comet

For the second time in less than a week, a comet is diving toward the sun. Polish comet hunter Michal Kusiak found it yesterday in coronagraph images from the Solar and Heliospheric Observatory:

Doomed Comet
© Spaceweather
Click here for an UPDATED movie

It's no coincidence that this comet is following the same path as its predecessor on Nov. 14th. They are both fragments of a single giant comet that broke apart about 2000 years ago. Astronomers call them "Kruetz sungrazers" after the 19th century German researcher, Heinrich Kreutz, who studied them in detail.

"November is one of the best months to discover Kreutz comets," notes Kusiak. "It's because the field of view of the SOHO coronagraph covers a larger-than-usual portion of the Kreutz track. December, May, and June are good, too."

With SOHO staring at just the right patch of sky, more sungrazers are probably in the offing. First, however, this one has a date with destiny, and it probably won't survive. Solar heating is expected to obliterate the icy sundiver later today or tomorrow. Stay tuned for movies of the death plunge.

Rocket

Comet bomber flyby pics show spaceball belching ancient dry ice

Professor Sunshine bitchslaps wet squirty tail theory

Excellent snaps sent back by a NASA probe craft during a rendezvous with the comet Hartley 2 have revealed that the spectacular "jets" of glowing gas which make it so spectacular result from dry ice subliming in its interior.

HartleyFlybyPhoto
© The RegisterA little bit of dry ice fabulousness

Meteor

New Discovered Sundiving Comet

New Comet
© SpaceWeather.com
A newly-discovered comet is diving toward the sun, and it will probably not survive the encounter. Click here to view a movie of the death plunge.

Japanese comet hunter Masanori Uchina first noticed the sundiver in coronagraph images from the Solar and Heliospheric Observatory (SOHO) on Nov. 13th. At the time it was a dim and distant speck, but now the comet is brightening rapidly as it approaches the hot sun. The bright glare of the sun hides these events from human eyes, but not from certain spacecraft: Join SOHO for a ringside seat.

Meteor

Comet Ikeya-Murakami Outburst

Comet Ikeya-Murakami (C/2010 V1) is definitely undergoing an outburst event. Italian astronomers Ernesto Guido and Giovanni Sostero assembled the following animation from images they obtained between Nov. 4th and Nov 9th:

Comet Ikeya-Murakami
© Space Weather.comComet Ikeya-Murakami
See the animated image here.

The sequence clearly shows an explosion in progress. "Only Nov. 7th is missing," they say, "because of rare cloudy skies over New Mexico, where the remotely-controlled telescope we used is located."

Another New Mexico observer, Leonid Elenin, estimates the size of comet's expanding atmosphere as 4x6 arcminutes. "There is also some evidence of two symmetrical jets emerging from the nucleus of the comet," he says.

Meteor

Newly Discovered Fast-Changing Comet Ikeya-Murakami

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© Leonid EleninComet Ikeya-Murakami (C/2010 V1) appears to brightening, signifying it could be in the middle of an outburst. Furthermore, the comet's gaseous head or "coma" bears a striking resemblance to that of Comet Holmes, which experienced a dramatic brightening and explosion in 2007.
A newly discovered comet that has caught the attention of skywatchers around the world appears to be undergoing some dynamic changes.

The comet, called Ikeya-Murakami (C/2010 V1), was first detected last week by amateur astronomers in Japan, but several other skywatchers have since been watching the icy wanderer's changing appearance over the last few days.

Russian astronomer Leonid Elenin, of Moscow, used the remotely operated ISON-NM telescope in New Mexico to observe the new Comet Ikeya-Murakami over the weekend.

"After the discovery, C/2010 V1 looked like a bright fuzzy ball, without details," Elenin told SPACE.com in an e-mail. "But after a few days, I was discouraged - [this] comet is rapidly changing."

The comet appears to brightening, signifying it could be in the middle of an outburst, according to Spaceweather.com. While the comet cannot be seen with the unaided eye, it should be easily detectable with backyard telescopes, the website added. Typically, however, finding a comet with a telescope can be tricky for those who are not familiar with sky charts and the night sky.