Comet in Deep Freeze Thaws as It Approaches Earth; UCF Plans Viewing
What some people are calling the comet of the century will be paying a visit to our part of the solar system in November, but scientists, including UCF’s Yan Fernandez, are already hard at work preparing for its arrival.
Comet ISON comes from the Oort Cloud, a refuge for icy debris jettisoned by Jupiter and the other giant planets to the distant reaches of the Sun’s influence back when the planets were just forming. ISON is creating quite the buzz within the space community since it is now making its first trip back toward the sun since then.
“It’s been in deep freeze for about four and a half billion years,” Fernandez said. “It’s pretty exciting because it likely has some clues locked inside its nucleus about how our solar system formed. Because comets from the Oort Cloud are so old and relatively pristine, we want to take advantage of what they can tell us about our solar system’s earliest days.”
Fernandez is part of NASA’s Comet ISON Observing Campaign team that’s been coordinating and facilitating observations of the comet since January. He is also part of another team that took the first infrared images of ISON with the Spitzer Space Telescope in June and released the pictures to the public late last month.
“As it gets closer to the Sun we expect to get more detailed information than ever before about the comet,” Fernandez said. “And on Thanksgiving Day, ISON will get to within only 750,000 miles of the Sun’s surface, so it’s going to get really hot. That’s pretty fantastic. It means all sorts of materials that we can study are going to be boiling off the comet – ices, rocks, metals. For the general public it could be a-once-in-a-lifetime opportunity to see a really bright comet. We’re hoping that in November and December you can see it with the naked eye at night right from your backyard.”
That is, if ISON doesn’t blow apart first.
ISON, like all comets, is a dirty snowball made up of dust and frozen gases such as water, ammonia, methanol, carbon monoxide and carbon dioxide. These are some of the fundamental building blocks of planets. As a comet gets closer to the sun, it heats up and its outer layers evaporate away. Spitzer images revealed that ISON is gassed up, with the carbon monoxide and carbon dioxide in its icy outer layer already boiling away and producing a bright tail. There is a possibility that as ISON gets closer to the sun, the evaporation of ices will become so intense that they will destroy the structural integrity of the comet before observers on Earth get a clear look.
Right now ISON is still too far away (well beyond Mars’s orbit) to know for sure how big it is and what its make up is exactly, Fernandez said.
“We might then get a better idea of what the comet will do and how bright it might get in November, but that’s one of the crazy things about comets – they like to defy predictions,” he said. “ISON might disintegrate to nothingness, it might survive but under perform, or it might indeed be a comet-of-the-century. We’ll just have to wait.”
Estimates are that ISON is less than 2 1/2 miles in diameter, about the size of a small mountain, and that it weighs between a few billion and several trillion pounds.
Should ISON remain intact come the fall, and if it seems like it will become bright enough, Fernandez said he will be organizing observation nights for the public from Robinson Observatory on UCF’s main campus. Fernandez is the observatory’s director.
“We’re in the planning stages right now,” Fernandez said. “But if people are willing, we expect to have some opportunities in mid to late November for the public. It may mean getting up at 4 a.m. for best viewing, but we’ll do it.”
Should ISON keep it together as it loops around the sun and boomerangs back toward the outer solar system, Fernandez says more viewing nights will be added in December. But it would still mean getting up before dawn.
“We’ll have a better idea when it gets a wee-bit closer, say some 200 million miles from the Sun in early September, so stay tuned,” he said.