Comet may light up Thanksgiving in Western Pa.
A 4.5-billion-year-old comet hurtling toward the sun could give viewers in Southwestern Pennsylvania something extra to look forward to on Turkey Day — if the gargantuan body of dust, ice and gas doesn't disintegrate before it gets there.
Comet ISON — named for the International Scientific Optical Network, a group of observatories in 10 countries that have organized to detect, monitor and track objects in space — was discovered in September 2012 and could come within a million miles of the sun on Thanksgiving Day.
The comet, which is the first visible to the naked eye in the Pittsburgh area since the late 1990s, was originally predicted to be as bright as the moon when the sun's particles hit it, said Dan Malerbo with the Carnegie Science Center.
Malerbo said those estimates are probably overstated, though the comet has brightened within the past week. Scientists are worried about the comet's future.
“It's still unpredictable,” said Malerbo, a program development coordinator with Buhl Planetarium. “We don't know what's going to happen. We don't know if it's going to survive.”
There's a chance the comet could disintegrate. As it approaches the sun, gravity could rip it apart. NASA reported on Saturday that ISON was passing Earth, which is an average distance of 93 million miles from the sun.
Wider than Australia, ISON originated in the Oort Cloud, a region of space that's home to billions of comets and other icy bodies. From the perspective of Southwestern Pennsylvania, the comet is heading toward the eastern horizon.
If it survives, the comet will swing around the sun and appear on the other side. Malerbo said scientists predict that could happen Thanksgiving morning.
Lou Coban, who manages the University of Pittsburgh's Allegheny Observatory in the North Side, said if the comet survives, it would be visible to the naked eye on the east-southeast horizon in the morning through early December.
Through late December and early January, as it climbs away from the horizon, it should be visible throughout the night. ISON will be closest to Earth on Dec. 26, when scientists with NASA report it will pass the planet again from about 28 million miles away.
Viewers in the area can look for the comet near the southeastern horizon this week and should use binoculars or a small telescope for a better glimpse, Malerbo said.
While Comet ISON could provide a brilliant show for viewers, Coban said scientists study the comet to better understand the makeup of the solar system.
“They think that most of the comets are sort of the building blocks of life in the solar system,” he said. “They have gas, dust and water, like dirty snowballs, and they may harbor certain kinds of bacteria that landed on early Earth.”
Astronomers can look at the light reflected from comets to determine their composition, he said. Malerbo said understanding the early solar system is important, but so is understanding comets so we can protect ourselves from them.
“Studying comets can also save our lives one day,” Malerbo said. “There could be a comet heading right at us, and by studying comets and learning about them, we're trying to come up with a plan to defend ourselves from a comet or an asteroid one day if we would need to.”
Anna Orso is a freelance reporter based in State College.