NASA scientists say a comet dubbed “Comet of the century” by reporters is expected to “graze” the sun later in the year.
Comet ISON, dubbed by some reporters as “comet of the century” is hurtling toward the sun and is expected to “graze” it later in the year, according to NASA scientists.
NASA scientists say on November 28, ISON will come within 800,000 miles of the astral surface, as it flies through the sun’s atmosphere.
If ISON does not break apart, it will shine brighter than the moon and will be briefly visible near the sun in broad daylight. According to scientists, the comet’s dusty tail stretching into the night sky could create a worldwide sensation.
NASA says it is too early to foresee what the comet will do. Nevertheless, astronomers are keeping a close eye on ISON as it dashes toward the sun. They hope to learn new information about the comet’s composition and behavior.
“Comet ISON is a sungrazer,” explained Karl Battams of the Naval Research Lab. “The orbit of the comet will bring it very close to the sun, which we know can be a spectacular thing.”
The three-to-four mile wide comet was first discovered by Russian astronomers last year. ISON at first glance was a tiny dot in the sky, scientists say. It was no different from thousands of other stars. It was near the orbit of planet Jupiter. A more powerful telescope revealed that it was indeed a comet.
“For an object at such extreme distance, it is actually very bright,” Battams said.
According to Matthew Knight of the of the Lowell Observatory, the comet’s glow indicates that is spewing gas and dust from a fairly large nucleus—“in the 1 to 10 km range.”
Scientists believe that the comet is making its first journey toward the solar system from the Oorth Cloud, a hypothesized spherical cloud made of icy planetisimals , nearly one light year from the sun.
From February until early May, the comet was situated inside planet Jupiter’s orbit. Photos of the Comet ISON showed a well-defined tail.
Scientist say comets grow a tail in the asteroid belt because the warmth from the sun turns their water ice into gas. The water and gas in the comet’s tail are called a coma. Scientists explain they are pushed into a tail because of pressure from solar wind and radiation.
Despite its distance from the sun, photos of the comet ISON show a well-defined tail which is unusually long.
Recently, there has been a reduction in comet’s activity. Scientists say this is because of its present location. They predict comet ISON is most likely developing a stronger tail as its water starts channeling out.
According to Karen Meech of the University of Hawaii’s the recent drop in activity might be associated with the comet’s first passage near the sun and a melting of ice that has led to a less active layer beneath.
Comets, historically have known to fizzle out when they come close to the sun. Referring to reporters dubbing the comet as “comet of the century,” Don Yeomans of NASA Near-Earth Object Program said it was premature to have such high expectations.
“I’m old enough to remember the last ‘Comet of the Century’,” Yeomans said. He was referring to a distant comet named Kohoutek. In 1973, Kohoutek, much like ISON looked like it would put on a great show.
However, much to the disappointment of scientists, the actual apparition was a let-down. Johnny Carson made jokes about it on the “Tonight Show.”
“It fizzled,” Yeomans said. “Comets are notoriously unpredictable.”
“Comet ISON has the potential to live up to the hype, but it also has the potential to do nothing,” Battams said.
Irrespective of whether ISON vanishes like its precursors or puts on a spectacular celestial show, the opportunity for astronomers to study comets is great.
By Perviz Walji