Comet ISON

‘Crazy, dynamic, unpredictable’ comet ISON still glowing, but is it still alive?

The unpredictable behavior of the ancient ISON comet has scientists scratching their heads, as the world’s space agencies had to quickly backtrack from their earlier claim that it had been destroyed in its encounter with the sun.

RT,

29 November, 2013

The 2km-wide relic has been traveling to meet our star for over a million years. But the “dinosaur bone of solar system formation,” as senior research scientist at Johns Hopkins University, Carey Lisse, dubbed it, did not shine as bright after its slingshot encounter around the sun on Thursday, forcing scientists and stargazers to conclude the celestial body had lost its tail and nucleus.

Karl Battams of NASA wrote on the space agency’s dedicated ISON blog about the confusion that the celestial body has caused.

“After impressing us yesterday, comet ISON faded dramatically overnight and left us with a comet with no apparent nucleus,” Battams said, also mentioning the deluge of calls he and the team had received from reporters, despite not being able to provide them with 100 percent clarity.

“As the comet plunged through the solar atmosphere, and failed to put on a show… we understandably concluded that ISON had succumbed to its passage and died a fiery death. Except it didn't! Well, maybe...,” he continued.

There were conflicting theories about the comet’s fate, but what emerged later in the photographic evidence forced everyone to backtrack.

The assumptions were dictated by the fact that traveling just over a million kilometers above our star’s surface would have melted all the comet’s ice at temperatures of over 2,000 degrees Celsius, while the sun’s magnetic field would have strongly influenced its behavior as well.

But claims of the ISON’s demise were later challenged with photographic evidence, as scientists saw a faint, but still bright glow of what they believe to be a piece of the comet.

Battams then went on to describe “a faint smudge of dust” visible in the images taken after the comet’s apparent exit from behind our star, which showed the faint glow traveling along ISON’s orbit. Admitting this could simply be a speck of dust, hopes were not high. However, the glow did not disappear.

“Now, in the latest LASCO C3 images, we are seeing something beginning to gradually brighten up again. One could almost be forgiven for thinking that there's a comet in the images!”

“We have a whole new set of unknowns, and this ridiculous, crazy, dynamic and unpredictable object continues to amaze, astound and confuse us no end,” Battams finished, asking everyone to be patient with further guess work. He added that if the glow is indeed the comet, we will be seeing it in the night sky in a matter of days.

NASA was not alone in retracting its earlier assessments: the European Space Agency stepped back from its earlier claims of ISON’s end as well.

However, scientists do not wish to make any further predictions as to its future at this point, because the comet could still just as easily stop releasing material and die out, if it indeed has not burned up after encountering the sun’s corona.

- ISON stands for International Scientific Optical Network

- Discovered September 2012 by two amateur Russian astronomers

- Originated in the Oort Cloud, about halfway from the sun to the next star

- Its age is about 4.5 billion years, like our solar system, where it originated

- Studying the comet should help our understanding of planet formation: when comets are destroyed from brushing close to the sun, the resulting vapors give clues of their chemical composition

Comet in southern skies

I'm in New Zealand and haven't heard about this before - there should be great excitement in the media! They prefer 'planet Key'

Bright Comet Pan-STARRS seen in skies over Australia

(and New Zealand)

Space Weather,

4 March, 2013

Comet Pan-STARRS (C/2011 L4) is inside the orbit of Mercury, brightening as it plunges toward the sun. Observers in the southern hemisphere say they can see Pan-STARRS with the unaided eye in the evening sunset sky. Michael White sends this view from Manawatu, New Zealand:

"As Comet Pan-STARRS was setting on the southwestern horizon, its nucleus was visible to the naked eye and its tail could just be seen with averted vision," says White. "Crops in the foreground were illuminated by nearby highway lights."

Several important dates are approaching. On March 5th, Comet Pan-STARRS makes its closest approach to Earth (1.1 AU), followed on March 10th by its closest approach to the sun (0.3 AU). As Comet Pan-STARRS passes the sun, solar glare might make it difficult to see even as the nucleus vaporizes and brightens. By March 12th and 13th, the comet will reappear in the sunset skies of the northern hemisphere not far from the crescent Moon; think photo-op! Light curves suggest that the comet's brightness will peak near 2nd magnitude, similar to the stars of the Big Dipper. Check the realtime comet gallery for the latest images.

The Russian meteorite

Russian meteorite: hunt for debris begins, but was it a comet?

Scientists say there are still many fragments to be found as debate starts over precise nature of celestial object

the Guardian,

18 February, 2013

A race for cosmic souvenirs has begun after scientists said there were still many pieces of the meteorite that fell to earth (video) near the Russian city of Chelyabinsk last week waiting to be found.

The extraterrestrial origin of 53 rock fragments collected on the frozen surface of Lake Chebarkul was confirmed during analysis conducted by the Urals Federal University in the early hours of Monday.

But this is just the start of the process of gathering the debris left by the large meteorite, which exploded on entering the earth's atmosphere and hit the ground in a series of fireballs on Friday.

Viktor Grokhovsky, a member of the Russian Academy of Science's meteorite committee, has been put in charge of the scientific search operation. "There are a lot more fragments to be discovered in many other places … it's only a matter of time," he said.

The search is being concentrated at the moment around a six-metre wide hole in Lake Chebarkul, about 50 miles from Chelyabinsk, discovered by locals shortly after the meteorite hit the ground.

Military divers spent much of the weekend scouring the bottom of the lake, but were hampered by poor visibility and found nothing.

Despite the failure of the divers, there was still likely to be a piece of meteorite in the lake of at least 50cm in diameter, said Grokhovsky.

Local officials said on Sunday that the formal search was being abandoned, but scientists will continue the hunt. No one from the eight-strong scientific team has yet been able to examine the whole surface of the lake because of a cordon put in place by the authorities over the weekend.

Analysis of the pieces recovered so far, none of which had a diameter greater than 1cm, suggests that 10% of the meteorite was made up of iron. Traces of sulphite and the mineral olivine were also present.

"It was a stone meteorite that belongs to a class of ordinary chondrite meteorites," said Grokhovsky.

Likely to be named Chebarkul after the lake where the first fragments were found, the meteorite is the biggest such object to hit the earth in more than 100 years.

Within the academic community there appeared to be a difference of opinion on Monday as to the exact nature of the object, when some experts said it was conceivable that it was a comet that had struck southern Russia at 9.20am on Friday.

"In Chelyabinsk we saw a type of comet in which there was almost no meteorite remaining," said Alexander Bagrov, a member of the Russian Academy of Sciences' Astronomy Institute, Interfax reported.

"It was mainly made up of a mass of ice, of which no trace is left."

The argument reflects the same debate that raged after the last big meteorite impact, the so-called Tunguska event in Siberia in 1908. For decades afterwards Russian scientists, trying to explain the absence of an obvious impact crater, argued over whether the blast was caused by a meteorite or a small comet.

While the intellectual debate was beginning on Monday, the clean-up operation in Chelyabinsk was winding down. The shockwave caused by the meteorite shattered windows across the region and injured about 1,500.

One woman was transferred to Moscow for treatment over the weekend and about 50 people remained in hospital. With night-time temperatures hovering around -20C, glass prices jumped as people rushed to replace broken panes.

2013 - year of the comet?

Sun-Grazing Comets As Triggers For Electromagnetic Armageddon

Large sun-grazing comets could bring on the sort of global electronics meltdown usually associated with electromagnetic pulse weapons or a full-scale nuclear exchange.

Forbes,

30 November, 2012

Or so says David Eichler, lead author of a forthcoming Astrophysical Journal Letters paper positing that a sun-grazing comet roughly the size of Hale-Bopp (with a nucleus some 30 kms in diameter), could trigger cosmic ray-generating shockwaves large enough to initiate a global electromagnetic Armageddon.

Eichler, an astrophysicist at Israel’s Ben-Gurion University of the Negev in Beer-Sheva, argues that satellites that weren’t in protection mode would be wiped out along with most of the world’s electronics — everything from micro-circuitry on cell phones to full-scale power stations.

If such a comet were the size of Hale-Bopp, Eichler says, the resulting solar flare would by far be the largest ever observed.

The comet gets compressed and then explodes in the solar atmosphere which, in turn, creates shockwaves, says Eichler.

Eichler thinks that such a sun-grazing comet may have triggered a large solar flare and cosmic ray-generating shockwaves as recently as 775 A.D., as indicated by tree ring analysis pointing to a sudden 1.2 percent spike in atmospheric Carbon 14.

“I’m not saying that [event] couldn’t have been caused by a magnetic solar flare, but we’ve never seen a solar flare nearly that big,” said Eichler.

Although the motion of such a sun-grazer would be the source of the shockwaves’ energy, the actual particle acceleration would happen within the sun’s magnetic field, explains Eichler.

Traveling at a 1000 kms per second, the shockwaves would reach earth in about a day and a half. And the effects would likely be much worse than the 1859 Carrington Event, a solar superstorm that wreaked havoc on telegraph lines and caused the aurora borealis to be visible as far south as Texas.

“From the looks of the tree ring data, fortunately, such events don’t happen but once every several thousand years,” said Eichler. “But by my estimates such a comet event might be 30 times stronger than the Carrington Event.”

Such a sun-grazing event’s resulting volley of cosmic rays would be funneled in along earth’s magnetic poles where magnetic resistance is the least, Eichler explains.

When the shockwaves hit the earth’s magnetic field, it would be like the hammer of a piano hitting a string, says Eichler. It would vibrate. And when a magnetic field line vibrates, he says, it makes an electric field which excites current in wires.

“It can excite the current and burn out the circuit,” said Eichler. “That’s the danger of giant electromagnetic pulses; these huge electric fields hit tiny micro-circuitry designed to handle only small currents.”

Although not expected to be harmful to humans, such an event could be extremely devastating to our electronic grid and could quite possibly send us back into a new Stone Age, says Eichler.

As for predicting future sun-grazers?

Most sun-grazing comets are too small to even make a ripple on the solar surface.

A recent exception was Comet Lovejoy, a long period sun-grazing comet which in December 2011, was observed to unexpectedly survive its closest solar approach.

Eichler says it’s quite possible that a very large comet could graze the sun once every several thousand years.

“If the Hale-Bopp-sized comet grazed the solar corona,” said Eichler, “then you’d get a much bigger solar flare than the Carrington Event. Hale-Bopp itself may become sun-grazing in the [distant] future.”

But there is one positive. Astronomers should, in principle, get a few years notice if such a large potential sun-grazing comet comes around again.

However, with a few classified military exceptions, our electronics remain unprotected against such potential magnetospheric trauma, he says.

Today, the Carrington Event itself would be devastating, says Eichler, and it wasn’t particularly powerful or all that unusual on an astrophysical timescale.

After completing his research, Eichler says he is most surprised by the fact that we’re still here to tell the tale.

“I didn’t realize the solar system was such a dangerous place,” said Eichler. “Just the fact that we’ve gone as long as we have without worse things happening may be why we’re here.”

Orbital diagram and current position of Comet C/2012 S1 (ISON). The comet is at approx. magnitude 18 and located about 6.25 AU from the Sun. Could this brighten into one of the brightest comets ever? It’s possible. It is possible that this comet could develop a spectacular tail or briefly approach the brightness of the full Moon toward the end of 2013. Alternatively, the comet could break up when it gets closer to the Sun. The comet was discovered by Russian scientists Vitali Nevski (Belarus) and Artyom Novichonok (Russia). It is currently approaching the Sun from between the orbits of Jupiter and Saturn. Comet ISON appears on course to achieve sungrazer status as it passes within a solar diameter of Sun’s surface in November 2013. Whatever survives will then pass nearest the Earth in late December 2013. Astronomers around the world will be closely tracking this large snowball to better understand its nature and how it might evolve during the next 15 months. (Image Credit: JPL)

Comet Nearing The Earth In 2013 May Be Brighter Than The Moon, Researchers Say

A recently discovered comet that is rapidly approaching the Sun could outshine the Moon in 2013, researchers think. The comet may even be visible in daylight, as the Great Comet of 1680 was. It’s expected to be visible towards the end of the year, roughly from October until the following January

Planet Save,

30 November, 2012

“The recently discovered object, known as comet ISON, is due to fly within 1.2 million miles (1.9 million km) from the center of the sun on Nov. 28, 2013 said astronomer Donald Yeomans, head of NASA’s Near Earth Object Program at the Jet Propulsion Laboratory in Pasadena, Calif.”

“As the comet approaches, heat from the sun will vaporize ices in its body, creating what could be a spectacular tail that is visible in Earth’s night sky without telescopes or even binoculars from about October 2013 through January 2014.” With such a bright object in the night sky during the latter part of the year, it may somewhat drown out what will otherwise be a spectacular year of meteor showers in 2013.

The comet will need to survive its approach to the Sun though, for that to happen. And it’s possible that the comet could disintegrate as it gets close to the sun.

Comets like ISON originate from the Oort Cloud, which is a vast area full of frozen rocks and ice near the edge of the solar system. They orbit around 50,000 times further away from the Sun than the Earth does. Occasionally, some of these objects bump each other out of orbit, and are pushed into a spiraling orbit towards the Sun.

“On Sept. 21, two amateur astronomers from Russia spotted what appeared to be a comet in images taken by a 16-inch (0.4-meter) telescope that is part of the worldwide International Scientific Optical Network, or ISON, from which the object draws its name.”

“The object was slow and had a unique movement. But we could not be certain that it was a comet because the scale of our images are quite small and the object was very compact,” astronomer Artyom Novichonok, one of the discoverers, wrote in a comets email list hosted by Yahoo.

“Novichonok and co-discoverer Vitali Nevski followed up the next night with a bigger telescope at the Maidanak Observatory in Uzbekistan. Other astronomers did likewise, confirming the object, located beyond Jupiter’s orbit in the constellation Cancer, was indeed a comet.”

“It’s really rare, exciting,” Novichonok wrote.

Interestingly, comet ISON is following a very similar path to the famous comet of 1680, which was bright enough to be visible in the middle of the day. It is following such a similar orbit that researchers theorize that they may both originate from the same fragmented parent body.

“Comet ISON could be the brightest comet seen in many generations – brighter even than the full moon,” wrote British astronomer David Whitehouse.

“In 2013, Earth has two shots at a comet show. Comet Pan-STARRS is due to pass by the planet in March, eight months before ISON’s arrival. The last comet to dazzle Earth’s night-time skies was Comet Hale-Bopp, which visited in 1997. Comet 17P/Holmes made a brief appearance in 2007.”

Some more information on the comet of 1680:

“C/1680 V1, also called the Great Comet of 1680, Kirch’s Comet, and Newton’s Comet, has the distinction of being the first comet discovered by telescope. Discovered by Gottfried Kirch on 14 November 1680, New Style, it became one of the brightest comets of the 17th century – reputedly visible even in daytime – and was noted for its spectacularly long tail. Passing only 0.42 AUs from Earth on 30 November, it sped around an incredibly close perihelion of 0.0062 AU (930,000 km; 580,000 mi) on 18 December 1680, reaching its peak brightness on 29 December as it rushed outward again. It was last observed on 19 March 1681. As of September 2012 the comet was about 253 AU from the Sun.”

“While the Kirch Comet of 1680-1681 was discovered and subsequently named for Gottfried Kirch, credit must also be given to Eusebio Kino, the spaniard Jesuit priest who charted the comet’s course. During his delayed departure for Mexico, Kino began his observations of the comet in Cadíz in late 1680. Upon his arrival in Mexico City, he published his Exposisión Astronomica de el cometa in which he presented his findings. Kino’s Exposisión astronómica is among the earliest scientific treatises published by an European in the New World.”

“Although it was undeniably a sungrazing comet, it was probably not part of the Kreutz family. Aside from its brilliance, it is probably most noted for being used by Isaac Newton to test and verify Kepler’s laws. Some of the orbital elements of comet C/2012 S1 are similar to that of the Great Comet of 1680, which suggests the two comets may have fragmented from the same parent body.”