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Comet ISON is headed for a near miss with the solar furnace, according to an update from NASA. It just so happens that ISON will make its closest approach to the sun on Thanksgiving Day. Currently, ISON is inside the orbit of Earth and zooming toward the fireball in our sky. There are three scenarios likely for ISON as it approaches, encounters and tries to endure the sun’s extreme temperatures.
For the moment, however, ISON is simply getting ready for a much bigger show in a few days. On November 12-13, an outburst from the comet increased its brightness 10-fold. Professional and amateur astronomers alike have reveled in the chance to take amazing photos of the comet’s gossamer green atmosphere and topsy-turvy tail.
Published on Nov 20, 2013
COMET ISON–SECOND HUGE OUTBURST – IT BRIGHTENS ANOTHER 6 FOLDS IN A DAY MAG +4,0 Astronomers working with the TRAPPIST telescope at ESO’s La Silla Observatory report that Comet ISON’s production of gas and dust surged another six-fold during the early hours of Nov. 19th. This marks the second outburst since Nov. 13th. Experienced observers put the comet’s rising magnitude near +4.0, well above the threshold of naked-eye visibility. The problem is, ISON is approaching the sun and becoming increasingly difficult to observe. Shahrin Ahmad of Kuala Lumpur, Malaysia, photographed the comet’s green core framed by twilight blue on the morning of Nov. 19th:
This is ISON’s first trip through the inner solar system and, consequently, astronomers have very little information to help them predict what will take place next. They can, however, rely on the experience of other comets to get a better idea of what might happen to ISON as it moves toward the solar furnace.
“I’ve grouped the possible outcomes into three scenarios, discussed in chronological order,” said Matthew Knight, Lowell Observatory astronomer, according to NASA. ”It is important to note that no matter what happens, now that ISON has made it inside Earth’s orbit, any or all of these scenarios are scientifically exciting. We’re going to learn a lot no matter what.”
The first possible scenario is that ISON spontaneously disintegrates before Thanksgiving Day. Fortunately for ISON, less than one percent of comets experience this fate. If it does disintegrate, the sheer number number of Earth- and space-based telescopes watching ISON will make the comet’s spontaneous disintegration the most-watched case of cometary disintegration ever.
The second possible scenario is that ISON suffers a slow death by sun. At some point during its close encounter with the solar furnace, ISON’s equilibrium temperature will approach 5,000 degree Fahrenheit. At this temperature, most of the dust and rock on the comet’s surface would be vaporized. Fortunately, the rate at which ISON will probably lose mass is relatively low compared to the actual size of the comet’s nucleus.
The third scenario is that ISON endures its close encounter with the sun and emerges with enough material to still be an active comet. If ISON survives, it would probably lose enough dust near the sun to generate a spectacular tail.
“Regardless of what happens, we’re going to be thrilled,” Knight said. “Astronomers are getting the chance to study a unique comet traveling straight from 4.5 billion years of deep freeze into a near miss with the solar furnace using the largest array of telescopes in history.”
Published on Nov 20, 2013
Comet Encke blazes by Mercury on November 20, 2013.