SCIENCE & ENVIRONMENT
29 November 2013 Last updated at 07:13 GMT
There were early doubts when nothing was seen in pictures where Ison should have been (cross)
An artist's impression of Esa's attempt next year to land on Comet 67P with its Philae probe
Hope still for 'dead' Comet Ison
Comet Ison, or some part of it, may have survived its encounter with the Sun, say scientists.
The giant ball of ice and dust was initially declared dead when it failed to re-emerge from behind the star with the expected brightness.
All that could be seen was a dull smudge in space telescope images - its nucleus and tail assumed destroyed.
But recent pictures have indicated a brightening of what may be a small fragment of the comet.
Astronomers admit to being surprised and delighted, but now caution that anything could happen in the coming hours and days.
This remnant of Ison could continue to brighten, or it could simply fizzle out altogether.
"We've been following this comet for a year now and all the way it has been surprising us and confusing us," said astrophysicist Karl Battams, who operates the US space agency-funded Sungrazing Comets Project.
"It's just typical that right at the end, when we said, 'yes, it has faded out, it's died, we've lost it in the Sun', that a couple of hours later it should pop right back up again," he told BBC News.
The European Space Agency (Esa), too, which had been among the first organisations to call the death of Ison, has had to re-assess the situation. A small part of the nucleus may be intact, its experts say.
There were early doubts when nothing was seen in pictures where Ison should have been (cross)
How much of the once 2km-wide hunk of dirty ice could have survived is impossible to say.
Passing just 1.2 million km above the surface of the Sun would have severely disrupted Ison. Its ices would have vaporized rapidly in temperatures over 2,000C. And the immense gravity of the star would also have pulled and squeezed on the object as it tumbled end over end.
Karl Battams said: "We would like people to give us a couple of days, just to look at more images as they come from the spacecraft, and that will allow us to assess the brightness of the object that we're seeing now, and how that brightness changes.
"That will give us an idea of maybe what the object is composed of and what it might do in the coming days and weeks."
Whatever happens next, comets are going to be a big feature in the news over the next year.
In 11 months' time, Comet Siding Spring will breeze past Mars at a distance of little more than 100,000km. And then in November 2014, Esa's Rosetta mission will attempt to place a probe on the nucleus of Comet 67P/Churyumov-Gerasimenko.
An artist's impression of Esa's attempt next year to land on Comet 67P with its Philae probeNASA says Comet ISON may have survived its sun skirmish (VIDEO)
Hold the phone. Experts now think Comet ISON may have survived its close encounter with the sun after initial reports showed it likely was vaporized.
Hold the phone. Experts now think Comet ISON may have survived its close encounter with the sun after initial reports showed it likely was vaporized.
ENLARGE
ISON appears as a white smear heading up and away from the sun. ISON was not visible during its closest approach to the sun, so many scientists thought it had disintegrated, but images like this one from the ESA/NASA Solar and Heliospheric Observatory suggest that a small nucleus may be intact. (ESA/NASA/SOHO/GSFC/Courtesy)
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Hold the funeral.
Experts now think Comet ISON may have survived its close encounter with the sun on Thanksgiving after initial reports showed it was likely vaporized.
More from GlobalPost: Stunning NASA video shows Comet ISON hurtling toward sun (VIDEO)
Material from the comet appeared on the other side of the sun Thursday night, surprising observers who had wrote off the giant snowball of frozen gases, rock and dust as DOA.
"The question remains whether it is merely debris from the comet, or if some portion of the comet's nucleus survived, but late-night analysis from scientists with NASA's Comet ISON Observing Campaign suggest that there is at least a small nucleus intact," NASA said on its website.
Karl Battams, a comet scientist for the Naval Research Laboratory, told CNN he agreed that some parts of ISON's nucleus survived perihelion.
More from GlobalPost: Scientists await Comet ISON's encounter with the sun
"Now it has emerged and started to brighten, we need to observe it for a few days to get a feel for its behavior," he said.
ISON skimmed just 730,000 miles over the fiery surface of the sun at roughly 1:30 p.m. ET Thursday.
Most astronomers had predicted it would not survive the fly-by.
Discovered by Russian scientists in 2012, the comet contains material assembled during the very formation of the solar system some 4.5 billion years ago.
The comet, known as Ison, was discovered last year when it was still far beyond Jupiter.
RELATED
A comet's 5.5-million-year journey to the inner solar system apparently ended during a suicidal trip around the sun, leaving no trace of its once-bright tail or even remnants of rock and dust, scientists said on Thursday.
The comet, known as Ison, was discovered last year when it was still far beyond Jupiter, raising the prospect of a spectacular naked-eye object by the time it graced Earth's skies in December.
Comet Ison passed just 730,000 miles (1.2 million km) from the surface of the sun at 1:37pm EST/1837 GMT on Thursday. Astronomers used a fleet of solar telescopes to look for the comet after its slingshot around the sun, but to no avail.
"I'm not seeing anything that emerged from the behind the solar disk. That could be the nail in the coffin," astrophysicist Karl Battams, with the Naval Research Laboratory in Washington, said during a live broadcast on Nasa TV."
"It's sad that it seemed to have ended this way, but we're going to learn more about this comet," he added.
At closest approach, the comet was moving faster than 217 miles per second(350 km per second) through the sun's atmosphere.
At that distance, it reached temperatures of 5,000 degrees Fahrenheit(2,760 degrees Celsius) - hot enough to vaporize not just ices in the comet's body, but dust and rock as well.
If the comet or any large fragments survived the close encounter with the sun, they would be visible to the naked eye in Earth's skies in a week or two.
The comet was discovered last year by two amateur astronomers using Russia's International Scientific Optical Network, or Ison.
Comets are believed to be frozen remains left over from the formation of the solar system some 4.5 billion years ago.
The family of comets that Ison belongs to resides in the Oort Cloud, located about 10,000 times farther away from the sun than Earth, halfway to the next star.
Occasionally, an Oort Cloud comet is gravitationally nudged out of the cloud by a passing star and into a flight path that millions of years later brings it into the inner solar system. Computer models show Ison was a first-time visitor.
The comet, known as Ison, was discovered last year when it was still far beyond Jupiter, raising the prospect of a spectacular naked-eye object by the time it graced Earth's skies in December.
Comet Ison passed just 730,000 miles (1.2 million km) from the surface of the sun at 1:37pm EST/1837 GMT on Thursday. Astronomers used a fleet of solar telescopes to look for the comet after its slingshot around the sun, but to no avail.
"I'm not seeing anything that emerged from the behind the solar disk. That could be the nail in the coffin," astrophysicist Karl Battams, with the Naval Research Laboratory in Washington, said during a live broadcast on Nasa TV."
"It's sad that it seemed to have ended this way, but we're going to learn more about this comet," he added.
At closest approach, the comet was moving faster than 217 miles per second(350 km per second) through the sun's atmosphere.
At that distance, it reached temperatures of 5,000 degrees Fahrenheit(2,760 degrees Celsius) - hot enough to vaporize not just ices in the comet's body, but dust and rock as well.
If the comet or any large fragments survived the close encounter with the sun, they would be visible to the naked eye in Earth's skies in a week or two.
The comet was discovered last year by two amateur astronomers using Russia's International Scientific Optical Network, or Ison.
Comets are believed to be frozen remains left over from the formation of the solar system some 4.5 billion years ago.
The family of comets that Ison belongs to resides in the Oort Cloud, located about 10,000 times farther away from the sun than Earth, halfway to the next star.
Occasionally, an Oort Cloud comet is gravitationally nudged out of the cloud by a passing star and into a flight path that millions of years later brings it into the inner solar system. Computer models show Ison was a first-time visitor.
Read more: http://www.universetoday.com/106832/zombie-ison-behaving-like-a-comet-stunned-astronomers-say/#ixzz2m5sMG0SdZombie ISON ‘Behaving Like A Comet’, Stunned Astronomers Say
Read more: http://www.universetoday.com/106832/zombie-ison-behaving-like-a-comet-stunned-astronomers-say/#ixzz2m5sMG0Sd
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Bright, brighter, brightest: these views of Comet ISON after its closest approach to the sun Nov. 28 show that a small part of the nucleus may have survived the encounter. Images from the Solar and Heliospheric Observatory. Credit: ESA/NASA/SOHO/GSFC
Talk about the Comeback Kid. After Comet C/2012 S1 ISON rounded the sun yesterday afternoon, professional astronomers around the world looked at the faded debris and concluded it was an “ex-comet.” NASA wrapped up an hours-long Google+ Hangoutwith that news. The European Space Agency declared it was dead on Twitter.
But the remnants — or whatever ISON is now — kept brightening and brightening and brightening in images from the NASA/European Space Agency Solar and Heliospheric Observatory. The pictures are still puzzling astronomers right now, almost a day after ISON’s closest encounter with the sun.
You can follow our liveblogged confusion yesterday, capped by a gobsmacking announcement from the Naval Research Laboratory’s Karl Battams, “We believe some small part of ISON’s nucleus has SURVIVED perihelion,” he said on Twitter. Since then, Battams wrote a detailed blog post, referring to images from the Large Angle and Spectrometric Coronagraph (LASCO) aboard SOHO:
“Matthew [Knight] and I are ripping our hair out right now as we know that so many people in the public, the media and in science teams want to know what’s happened. We’d love to know that too! Right now, here’s our working hypothesis: As comet ISON plunged towards to the Sun, it began to fall apart, losing not giant fragments but at least a lot of reasonably sized chunks. There’s evidence of very large dust in the form of that long thin tail we saw in the LASCO C2 images.
After its closest approach to to the sun on Nov. 28 (left), Comet ISON appeared a dim shadow of its former self (at right). “The comet may still be intact,” NASA wrote on Nov. 29. Images from the Solar and Heliospheric Observatory. Credit: ESA/NASA/SOHO/Jhelioviewer
Then, as ISON plunged through the corona, it continued to fall apart and vaporize, and lost its coma and tail completely just like Lovejoy did in 2011. (We have our theories as to why it didn’t show up in the SDO images but that’s not our story to tell – the SDO team will do that.) Then, what emerged from the Sun was a small but perhaps somewhat coherent nucleus, that has resumed emitting dust and gas for at least the time being. In essence, the tail is growing back, as Lovejoy’s did.So while our theory certainly has holes, right now it does appear that a least some small fraction of ISON has remained in one piece and is actively releasing material. We have no idea how big this nucleus is, if there is indeed one. If there is a nucleus, it is still too soon to tell how long it will survive. If it does survive for more than a few days, it is too soon to tell if the comet will be visible in the night sky. If it is visible in the night sky, it is too soon to say how bright it will be…
This morning (EST), Battams succinctly summarized the latest images he saw: “Based on a few more hours of data, comet #ISON appears to be… well, behaving like a comet!”, he wrote on Twitter.
NASA issued a status update this morning saying it’s unclear if this leftover is debris or an actual nucleus, but added that “late-night analysis from scientists with NASA’s Comet ISON Observing Campaign suggest that there is at least a small nucleus intact.” NASA, as well as Battams, pointed out that comet has behaved unpredictably throughout the 15 months scientists and amateurs have been observing it.
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Swift Satellite Takes a Look at Comet ISONRead more: http://www.universetoday.com/106832/zombie-ison-behaving-like-a-comet-stunned-astronomers-say/#ixzz2m5sABJK8
(CNN) -- Hold the obituary. Experts now think Comet ISON -- or at least part of it -- survived its close encounter with the sun.
Karl Battams, a comet scientist for the Naval Research Laboratory, said it is believed some parts of ISON's nucleus survived perihelion.
"It now looks like some chunk of ISON's nucleus has indeed made it through the solar corona, and re-emerged," he said. "It's throwing off dust and (probably) gas, but we don't know how long it can sustain that."
However, he said, its fate is uncertain.
"Now it has emerged and started to brighten, we need to observe it for a few days to get a feel for its behavior," Battams said.
ISON swept about 730,000 miles over the sun's surface Thursday about 2 p.m. ET.
A fleet of spacecraft watched ISON plunge toward the sun, includingNASA's STEREO satellite, the European Space Agency/NASASOHO spacecraft and the Solar Dynamics Observatory.
Comets are giant snowballs of frozen gases, rock and dust that can be several miles in diameter. When they get near the sun, they warm up and spew some of the gas and dirt, creating tails that can stretch for thousands of miles.
Most comets are in the outer part of our solar system. When they get close enough for us to see, scientists study them for clues about how our solar system formed.
Astronomers Vitali Nevski and Artyom Novichonok discovered ISON last year using a telescope near Kislovodsk, Russia.
ISON -- officially named C/2012 S1 -- was 585 million miles away at the time. Its amazing journey through the solar system had been chronicled by amateur astronomers and by space telescopes.
"From the beginning, ISON has confused, surprised and amazed us, and in hindsight its latest little escapade really should not shock us," Battams said. "Nonetheless, this has been one of the most extraordinary comets we have ever encountered, and just goes to reiterate how beautiful, dynamic and exciting our universe is."
Observers have been watching the comet for more than a year, hoping it would survive its sunbath and emerge to put on a sky show, visible to the naked eye in the Northern Hemisphere.
Earlier Thursday, NASA scientists had pretty much declared ISON dead at the end of a Google Hangout to watch the comet swing by the sun. But professional and amateur astronomers were undeterred by the reports and kept analyzing NASA satellites. They found images that clearly show something emerging from the sun.
"What we see here is the dust tail emerging first, pointing away from the sun," said Padma Yanamandra-Fisher with the Space Science Institute and a member of the ISON Observing Campaign.
A video made by observing campaign member John Maclean shows the comet slicing toward the sun and then something -- apparently ISON -- emerging from the other side. Maclean is a fellow of the Royal Astronomical Society at Norman Lockyer Observatory Sidmouth in Devon, England.
The discovery stunned many in the comet-watching community and led some to nickname ISON the zombie comet.
Others repeated an old joke about comets and cats.
"Comets are like cats; they have tails, and they do precisely what they want," David H. Levy said.
This comet also seems to have something else in common with cats -- nine lives.
Read more: http://www.universetoday.com/106832/zombie-ison-behaving-like-a-comet-stunned-astronomers-say/#ixzz2m5rlHyD9
