Wednesday, 9 January 2013

Comet Ison

 Spectactular Comet Ison May Even Outshine The Moon

In 2013 we will have the chance of a lifetime to see one of the brightest objects in the sky ever!
The approaching comet Ison may even outshine the Moon, astronomers say.
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 November 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.
If the comet survives, that is.
It has taken Comet Ison millions of years to reach us traveling all the way from the so-called Oort cloud, a cluster of frozen rocks and ices that circle the sun about 50,000 times farther away than Earth's orbit.
According to astronomer Andrew Fraknoi a passing star could have flung the comet our way from the Oort Cloud, a distant realm of ice chunks at the outer limits of the solar system. Image credit: Artistic impression NASA
On September 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.
Comet Ison is for the moment a faint object, visible only in sophisticated telescopes, but that will change in the next few months.
British astronomer David Whitehouse in The Independent reports that "by the end of summer it will become visible in small telescopes and binoculars.
By October it will pass close to Mars and things will begin to stir. The surface will shift as the ice responds to the thermal shock, cracks will appear in the crust, tiny puffs of gas will rise from it as it is warmed. The comet's tail is forming.
Slowly at first but with increasing vigour, as it passes the orbit of Earth, the gas and dust geysers will gather force. The space around the comet becomes brilliant as the ice below the surface turns into gas and erupts, reflecting the light of the Sun.
Now Ison is surrounded by a cloud of gas called the coma, hundreds of thousands of miles from side to side. The comet's rotation curves these jets into space as they trail into spirals behind it. As they move out the gas trails are stopped and blown backwards by the Solar Wind.
 Next year's comet is predicted to remain in the skies for weeks.
By late November it will be visible to the unaided eye just after dark in the same direction as the setting Sun. Its tail could stretch like a searchlight into the sky above the horizon. Then it will swing rapidly around the Sun, passing within two million miles of it, far closer than any planet ever does, to emerge visible in the evening sky heading northward towards the pole star. It could be an "unaided eye" object for months.
When it is close in its approach to the Sun it could become intensely brilliant but at that stage it would be difficult and dangerous to see without special instrumentation as it would be only a degree from the sun.
Remarkably Ison might not be the only spectacular comet visible next year.
Another comet, called 2014 L4 (PanSTARRS), was discovered last year and in March and April it could also be a magnificent object in the evening sky. 2013 could be the year of the great comets.
As Comet Ison heads back to deep space in 2014 the sky above it would begin to clear as the dust and gas geysers loose their energy. Returning to the place where the Sun is a distant point of light, Comet Ison may never return. Its tail points outward now as the solar wind is at its back, and it fades and the comet falls quiet once more, this time forever."
Comet Ison gives all stargazers reason to await and admire a remarkable object that is so bright it can even be visible in daylight.

The Comet of the Century
Last September, the International Scientific Optical Network (ISON) near Kislovodsk, Russia, discovered comet C/2012 S1 (ISON). Though its closest approach to Earth is a year away, the celestial visitor is already billed as the "comet of the century." That's because it may be a first-time visitor to the solar system that will warm and then erupt with a lot of outgassing from pristine ices.
invisible soldier
On Nov. 28, 2013 the comet will skim above the sun's surface at a distance slightly greater than the separation of the Earth and moon. Not doubt there will be pseudoscience predictions of the comet wreaking havoc by raising tides on the sun. The exact opposite will be the case. The sun's tidal pull could tear apart the comet into small pieces, as has been the case for previous sungrazer-class comets.
Comet ISON is due to pass within 37 million miles of Earth in January 2014. I'm expecting to see all types of outrageous claims that the object's feeble gravity will yank on Earth to trigger volcanoes and earthquakes.
Comet ISON has been compared with the Great Comet of 1680 which, according to contemporary accounts, caused New Yorkers to be "overcome with terror at a sight in the heavens such as has seldom greeted human eyes." A day of fasting and humiliation was set-aside in order that "the wrath of God might be assuaged."
Likewise, soothsayers will quickly note that the comet will be at it brightest one month before Christmas 2013. "This comet, if it lives up to its billing, certainly could point to the glorious soon coming of the Lord Jesus Christ from heaven!" predicts one religious website.
The fact that the comet is anticipated to get as bright as the moon will only fuel religious and mystical speculation about its timing and significance as an omen. Chill out folks, it's just another 4 billion year-old primeval chunk of ice from the solar system's deep freeze, the Oort cloud.