Hot news:
Astana residents stocking up on dollars 'just in case' Kazakhstan Prosecutor General warns devaluation rumors may lead to criminal liability National Bank Governor's advisor refutes Kazakh currency devaluation rumors Kazakhstanis recommended to postpone Hajjs to Saudi Arabia Meningitis hits another city in Kazakhstan Elite Turkic warrior burial discovered in Kazakhstan Russia provides Air Astana with route to fly around Ukrainian fighting zones Yosemite Park fire threatens famous giant sequoia trees Putin and Nazarbayev talk Ukraine Ablyazov's wife deportation to Kazakhstan illegal: Italy Court of Cassation Kazakhstan to toughen monetary policies should pressure on Russian ruble persist Arum not interested in Cotto-Golovkin fight Kazakhstan lifts ban from Russian fuel imports Rumors of second devaluation in Kazakhstan are speculations: experts Rescuers battle rains after India landslide, 150 feared dead Top beauties of World Cup 2014 Final Kazakhstan not among 35 most powerful militaries Chief doctor denies Astana meningitis outbreak New treatment helps children with ICP walk in Kazakhstan Kazakhstan to introduce mobile signature in 2015 Mother sentenced to 8 years of prison for selling her children in Kazakhstan 6 y.o. Sophie Manasyan wins Constellation of Vienna in Austria. Kazakhstani airline buys Sukhoi Superjet 100 airplanes Turks teach Astana hotel personnel nuances of Eastern hospitality for EXPO-2017 Irrigation water shortage in Kyrgyzstan hits Kazakhstan No People's IPO for Air Astana in near future: Samruk Kazyna Russia's Lukoil sells filling stations in Ukraine Myanmar makes $2.3mn heroin bust in 'Golden Triangle' Ex-TEPCO execs should be charged over Fukushima: panel Kazakhstan's athlete becomes Internet sensation China court hears first gay 'conversion therapy' case George W. Bush writes bio of his US president dad Former aide to Britain's Prince Philip charged with sex abuse Mexico ex-governor's son faces questions over cartel meet Ex-spy Litvinenko death inquiry to open in Britain Argentina faces default as 'vulture fund' talks fail Beef exporter confidence returns in land of the holy cow Toasts and tears of joy as Germany started WWI Uighur group says nearly 100 casualties in China clash Oil production at Kashagan to be resumed in 2016: Kazakhstan’s Oil Minister Development of Almaty city master plan postponed Chinese ready to help Kazakhs with Silk Road tourism development project Abel Sanchez talks Golovkin-Cotto fight Astana-Borovoye toll road to bring $6.5 million in 2014 UN takes aim at Islamist oil grab in Syria, Iraq IBF champion Sam Soliman wants to fight Golovkin to unify titles Strong quake hits Mexico, one dead Kerry heads to India to end relationship rut Cambodia court begins genocide trial of Khmer Rouge leaders Suspected meningitis knocks down 160 in Astana Canada says China hacked science agency computers US and Europe hit Russia with toughest sanctions yet Twitter flies on surprisingly strong numbers At least 24 dead in Guinea rap concert stampede: hospital Deadly Israeli shelling hits UN school as Hamas mulls truce Europe launches last resupply ship to space station Giant public artwork divides opinion in Sydney Tiger campaign threatened by poor data: WWF Bank of Cyprus completes $1 bn private share placement China's former security chief under investigation: Xinhua Zarina Diyas heads to Citi Open 1/8 finals in Washington DC New deputy finance minister in Kazakhstan With new default looming, Argentina urges calm Historical burial site containing child and noble woman remains discovered in South Kazakhstan Inuit village sues to block oil surveys in Canada's Arctic Karzai cousin killed in Afghan suicide attack: officials Airbus cancels order for six A380s from Skymark Heavy rains in Kokshetau Kazakh diplomats not willing to repay £1.8 million 'debt' of London congestion charges Linda Ronstadt awarded White House arts honor Two frontline soldiers commit suicide in S. Korea Venezuela sings Happy Birthday to late president Chavez EU to impose new Russia sanctions as fighting blocks MH17 probe NASA rover breaks out-of-this-world distance record Historic Chinese church gutted by fire: Xinhua Nissan says April-June net profit jumps 37% on-year to $1.1 bn Geneticists offer clues to better rice, tomato crops Japan rolls out more sanctions over Ukraine Tennis: Kazakhstani Zarina Diyas gets in WTA Top-100 Facebook wants to beam the Internet from the sky Peace Corps withdraws from W. Africa over Ebola fears 25 in Indonesia dead in Eid boat sinkings

Is the 'Christmas Comet' cracking up?

Friday, 18.10.2013, 16:05
Comments (0)
Is the 'Christmas Comet' cracking up?
©Reuters/NASA, ESA, and the Hubble Heritage Team
An incoming comet that skygazers had hoped would provide one of the greatest celestial shows of the century, could be a fizzle, AFP reports.

So say astronomers tracking the eagerly-awaited Comet ISON as it races to a searing encounter with the Sun.

Formally known as C/2012 S1 (ISON), the comet was spotted by a pair of hard-working amateur Russian astronomers, Vitaly Nevski and Artyom Novichonok, on September 21, 2012.

It is called ISON because they used a telescope called the International Scientific Optical Network near Kislovodsk, in the northern Caucasus.

After the discovery was validated by the International Astronomical Union (IAU), interest in the enigmatic wanderer became huge.

Calculations showed that after looping around the Sun, the comet would become a blaze of glory towards the end of the year -- a timing that gave it the tabloid title of "Christmas Comet" or even "Comet of the Century."

But fears are multiplying that the great show will be cancelled.

Light signatures from ISON, which has just streaked past Mars, indicate the comet is about to break up, says Ignacio Ferrin, an astrophysicist at the University of Antioquia in Medellin, Colombia.

"This disintegration will take place before it reaches perihelion," Ferrin told AFP in an email. Perihelion is an orbit's closest point to the Sun, which ISON is supposed to reach on November 28.

"There are also predictions for disintegration at perihelion. But based on the evidence, the comet will not get there," said Ferrin.

He explained that comets typically brighten as they get closer to the Sun, crossing a temperature threshold that causes their icy surfaces to evaporate, depositing water vapour, other gases and dust in their wake.

But, said Ferrin, the light curve from ISON slowed down and then remained practically constant, with no sign of greater brightness, as it raced forward.

This is a signature that matches four previous comets that have broken up catastrophically, he said.

"Comets in general appear to be quite fragile, and are observed to fragment or split," said Duncan Steel, a visiting astronomer at Armagh Observatory in Northern Ireland.

"It has always been a good bet that ISON would do this, and there is now evidence that this may be now occurring."

Cursed to wander Solar System

Comets are believed to be huge clusters of primeval dust and frozen ices, including water and organic molecules that, say some, delivered the building blocks of life to the infant Earth.

Doomed to orbit the Sun in periods that can range from years to many millennia, comets undergo thermal stress as they near the star.

Veterans that make short-period flybys, such as Halley's Comet, appear to have a crust of silicates and "tarry" carbon molecules to insulate them from the heat.

But rare visitors such as ISON have no such protection, said Steel. Internal gases start to expand in the heat, stressing the crumbly "dirty snowball" structure.

Comets can also be torn apart by gravitational forces if they cross the path of a planet.

This famously happened with Comet Shoemaker-Levy 9, whose fate was dictated by Jupiter. Fragments of the comet smashed into the jovian giant in 1994.

Even if the gloomy predictions are wrong, ISON still has to survive the climax of its ordeal by fire.

A "Sun-grazing" comet, at perihelion, it will be less than 1.2 million kilometres (730,000 miles) from the surface of the star -- just three times the distance between the Earth and Moon -- and subjected to temperatures of 2,800 degrees Celsius (5,000 degrees Fahrenheit).

According to preliminary estimates by the Lowell Observatory and Southwest Research Institute in Arizona, ISON has a good chance of surviving the solar furnace and gravitational rip at perihelion.

Comets smaller than 200 metres (650 feet) across almost always are destroyed when passing at such a distance. ISON appears be between 1,000 and 4,000 metres (1,000 and 4,000 yards) across.

What, though, will be left of ISON after it has kissed the Sun?

Will enough remain for it to be a real comet? Or will it be just a sad, shrivelled lump?

"We have absolutely no idea," said Patrick Rocher, of the Institute of Celestial Mechanics at the Paris Observatory.
Views: 3    Comments: 0
preloader
Add a comment
preloader

2014
2008
2009
2010
2011
2012
2013
2014
August
January
February
March
April
May
June
July
August
September
October
November
December

News
Archive

Mo Tu We Th Fr Sa Su
1 2 3
4 5 6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 31

Feature stories

Поделиться:
Is the 'Christmas Comet' cracking up?
http://en.tengrinews.kz/userdata/news_en/2013/news_23397/thumb_b/photo_33640.jpg
http://en.tengrinews.kz/science/Is-the-Christmas-Comet-cracking-up-23397/