Following various reports on Nov. 28 stating that Comet ISON did not survive its fiery encounter with the sun, astronomers were surprised when something shot back into space from the other side of the star, leaving many to believe that ISON, or parts of it, may have managed to cheat death.
NASA is baffled too, and issued a statement on Monday saying that its scientists continue to investigate and understand what became of Comet ISON. The space agency believes that the celestial body shrank in size considerably as it rounded the sun, but confusion surrounds the question of what, if anything, of the comet escaped the sun’s enormous heat and gravity.
“The question remains as to whether the bright spot seen moving away from the sun was simply debris, or whether a small nucleus of the original ball of ice was still there. Regardless, it is likely that it is now only dust,” a NASA statement said.
When Comet ISON made its closest approach to the sun, it was visible through images called coronagraphs taken by NASA's Solar Terrestrial Relations Observatory, or STEREO, and the joint European Space Agency/NASA Solar and Heliospheric Observatory, or SOHO.
Coronagraphs block out the sun and a considerable distance around it, in order to better observe dim structures in the sun's atmosphere. As such, there was a period of several hours when the comet was obscured in these images, blocked from view by the sun.
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During this time, NASA's Solar Dynamics Observatory could not see the comet, leading many scientists to deduce that it had disintegrated completely. However, something did show up in the SOHO and STEREO coronagraphs after some time, though it was significantly less bright.
According to NASA, it is likely that there is no nucleus left, but the space agency also said that the best chance to know for sure will depend on the Hubble Space Telescope, which will make observations of the comet later in December.
Meanwhile, Karl Battams of the U.S. Navy's Sungrazer Comets citizen-science project and the NASA-sponsored Comet ISON observing campaign, posted a eulogy for ISON, which “lived a dynamic and unpredictable life.”
“Tragically, on November 28, 2013, ISON's tenacious ambition outweighed its ability, and our shining green candle in the solar wind began to burn out,” Battams wrote.