Friday 17 January 2014

ISON’s tonight you can see the last of this comet

Comet ISON took us on a roller coaster ride last year when it swung perilously close to the sun.
Scientists all over the world were on the edge of their seats, urging the comet to survive its close encounter. 
But the optimistically-named 'comet of the century' was pronounced dead in December causing astronomers to mourn the loss of the sky show that once promised to light up Earth. 
Now ISON could have another trick up its sleeve. Scientists believe an unusual meteor shower from the comet could hit Earth tonight.
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Paul Wiegert's model of the Comet ISON debris stream and how it will hit Earth's orbit
Meteor researcher Paul Wiegert of the University of Western Ontario has been using a computer to model the trajectory of dust ejected by the comet.
According to his computer models, the debris stream is populated with extremely tiny grains of dust, no more than a few microns wide.
Pushed toward Earth by the gentle radiation pressure of the sun, they will be hitting at a speed of 125,000 mph (56 km/s).
Because the particles are so small, Earth’s upper atmosphere will rapidly slow them to a stop.
Scientists now believe an unusual meteor shower from comet ISON could hit Earth tonight. This image shows the position of the radiant for any possible ISON debris in Leo
Scientists now believe an unusual meteor shower from comet ISON could hit Earth tonight. This image shows the position of the radiant for any possible ISON debris in Leo
In this frame grab taken from an enhanced video made by Nasa's STEREO-A spacecraft, comet ISON, left, approaches the sun on November 25
In this frame grab taken from an enhanced video made by Nasa's STEREO-A spacecraft, comet ISON, left, approaches the sun on November 25

SCIENTISTS PLAN TO HARVEST ISON DUST IN THE ANTARCTIC

 Scientist at the Vostok Antarctic station are currently in place to gather any dust from the comet ISON to help them find the 'basic building blocks' of life.
Dust gathering can take place the Antarctic because the air over the polar continent is cleaner compared to more inhabited locations.
The scientists plan to use five 150-square metre polyethylene canvases as traps.  Each trap will be unrolled and left in the hope that some comet particulates would fall on it.
Then they will be preserved in chemically inert argon gas and shipped to St. Petersburg for microscopic study, which is expected to start in May.
‘Instead of burning up in a flash of light, they will drift gently down to the Earth below,’ said Professor Wiegert.
Scientists are unsure exactly when or if the meteor shower will happen, but have estimated that it may reach its peak tonight. 
The invisible rain of comet dust, if it occurs, would be very slow. It can take months or even years for fine dust to settle out of the high atmosphere. 
But while the dust is in the atmosphere it could produce noctilucent clouds (NLCs).
NLCs are icy clouds that glow electric-blue as they float more than 80 km above Earth's poles. Data from Nasa’s AIM spacecraft suggests that NLCs are seeded by space dust.
Tiny meteoroids act as nucleating points where water molecules gather; the resulting ice crystals assemble into clouds at the edge of space itself.
This is still speculative, but Comet ISON could provide the seeds for a noctilucent display. Electric-blue ripples over Earth's polar regions might be the only visible sign that a shower is underway.
Ahile the dust is in the atmosphere it could produce noctilucent clouds such as the ones seen here
Ahile the dust is in the atmosphere it could produce noctilucent clouds such as the ones seen here
German amateur astronomer Waldemar Skorupa recorded this image from Kahler Asten, in Germany, on November 16, 2013
ISON, which has been dubbed the 'comet of the century', was visible to the naked eye in November

MILESTONES IN ISON'S JOURNEY

Comet ISON headed towards the centre of our solar system in Novermber passing within 1.2 million miles of the sun’s surface.
At the time of discovery in September 2012, ISON was over 584 million miles from the sun.
Its average speed in July was 55,405mph. It continued to accelerate steadily until November when it whipped around the sun at an astonishing 425,000mph.
After much speculation, the optimistically-named ‘comet of the century’ was pronounced dead in December after its close encounter with our star.
Astronomers who had followed the ice ball mourned the loss of the sky show that once promised to light up during December. 
Scientists now believe an unusual meteor shower from the comet's remains could hit Earth tonight.
Professor Wiegert notes another strange event: ‘The shower is going to hit our planet from two directions at once.’
When Earth passes through the debris stream, we will encounter two populations of comet dust.
One swarm of dust will be following the Comet ISON into the sun. Another swarm will be moving in the opposite direction, pushed away from the sun by solar radiation pressure.
The streams will pepper opposite sides of Earth simultaneously.
‘In my experience, this kind of double whammy is unprecedented,’ he said.
Bill Cooke, lead scientist at Nasa’s Meteoroid Environment Office, added there's little danger to Earth-orbiting spacecraft.
‘These particles are just too small to penetrate the walls of our satellites, and they don't stand a chance against the heavy shielding of the ISS.’
However, he adds, mission operators will be alert this week for possible anomalies.
Scientist at the Vostok Antarctic station are already in place to gather any dust from the comet ISON to help them find the 'basic building blocks' of life.
Noctilucent clouds (NLCs)  are icy clouds that glow electric-blue as they float more than 80 km above Earth's poles. Data from Nasa¿s AIM spacecraft suggests that NLCs are seeded by space dust
Noctilucent clouds (NLCs) are icy clouds that glow electric-blue as they float more than 80 km above Earth's poles. Data from Nasa¿s AIM spacecraft suggests that NLCs are seeded by space dust
Sergey Bulat from St. Petersburg Institute of Nuclear Physics, told RIA Novosti:‘We expected the comet to survive and hoped to gather some large particulates in December.
‘Now if we get something, it would be particulates from the coma [the major part of the head of a comet] and tail left when it was approaching the sun,’ he said.
Dust gathering can take place the Antarctic because the air over the polar continent is cleaner compared to more inhabited locations.
The scientists plan to use five 150-square metre polyethylene canvases as traps.  Each trap will be unrolled and left in the hope that some comet particulates would fall on it.
Then they will be preserved in chemically inert argon gas and shipped to St. Petersburg for microscopic study, which is expected to start in May.
Nasa said sky watchers should also be on alert. The odds of seeing anything are low, but comet ISON could be full of surprises.
Last year the 'comet of the century' was spotted on a trajectory towards the sun before appearing to disappear, yet shortly afterwards bright lights (pictured top left) were spotted that some scientists have claimed could be the comet's nucleus
Last year the 'comet of the century' was spotted on a trajectory towards the sun before appearing to disappear, yet shortly afterwards bright lights (pictured top left) were spotted that some scientists have claimed could be the comet's nucleus


Read more: http://www.dailymail.co.uk/sciencetech/article-2540526/ISONs-hurrah.html#ixzz2qeGyloGp
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