A dramatic new series of images from NASA’s Solar and Heliospheric Observatory (SOHO) continue to leave open the question of whether Comet ISON survived its scorching swing around the sun yesterday and may even be spotted by observers on Earth as it pulls away from the Sun over the weekend.
The comet seemed to fade and then disappear on Thursday just ahead of its closest approach to the sun at 1:44 pm EST. When it failed to turn up in images taken by the Solar Dynamics Observatory, NASA’s most advance camera capable of looking toward the sun, scientists glumly called the comet a goner.
But a few hours later, a faint train of debris following along the comet’s orbit appeared to brighten, as though emitting fresh material. As this image shows, the trend continued into Friday morning, with the comet appearing to taken on a broad wing-like structure with a brightness roughly equal to some of the brightest stars in the night sky.
Comets are chunks of ice containing dusty material. When the ice is vapourized by solar heating, dust is released. Most of the light emitted by a comet when it is near the sun is simply sunlight reflecting off the dust.
Scientist aren’t sure if the object that they are now following is the surviving nucleus of ISON or merely a cloud of dust and rubble that is gradually spreading out. But if this “ghost of ISON” continues to maintain its brilliance it may show up in backyard telescopes, binoculars or even become visible to unaided eye. If so, the place to look is just above the eastern horizon about half an hour before sunrise. Most projections say December 1st (Sunday morning) is the most likely day that something -- if anything -- will appear.
Comet ISON was first spotted by a Russian telescope in September last year, and became something of celestial flash in the pan this week for its vivid tail — visible by the naked eye — and compelling backstory of impending doom.
The comet was two-thirds of a mile wide as it got within 1.6 million kilometres of the sun, which in space terms basically means grazing it.
NASA solar physicist Alex Young said Thursday the comet had been expected to show up in images from the Solar Dynamics Observatory spacecraft at around noon eastern time (1700 GMT), but almost four hours later there was “no sign of it whatsoever.”
Images from another spacecraft showed a light streak continuing past the sun, but Young said that was most likely a trail of dust continuing in the comet’s trajectory.
However, instead of fading, that trail appeared to get brighter Friday, suggesting that “at least some small fraction of ISON has remained in one piece,” U.S. Navy solar researcher Karl Battams wrote on his blog. He cautioned that even if there is a solid nucleus, it may not survive for long.
Two years ago, a smaller comet, Lovejoy, grazed the sun and survived, but fell apart a couple of days later.
“This is what makes science interesting,” said Fitzsimmons, who specializes in comets and asteroids. “If we knew what was going to happen, it wouldn’t be interesting.”
ISON’s slingshot toward the sun left astronomers puzzled and excited at the same time.
Made up of loosely packed ice and dirt, the space rock came from the Oort cloud, an area of comets and debris on the fringes of the solar system.
With files from the Associated Press