Tuesday, July 30, 2013, 1:45PM: Meteorologists are not the only ones to have occasional trouble making accurate predictions – astronomers and entomologists can certainly be added to the list. First, there was Comet PANSTAARS which was supposed to be an impressive sight in the April skies, but it generally turned out to be a disappointment. Then there was the predicted massive 17-year cicada invasion which turned out to be sporadic at best in the Mid-Atlantic region. Now, it is looking more and more like the so-called “Comet of the Century”, Comet ISON, indeed may turn out to be a bust.
Astronomers have found that Comet ISON, which is currently moving towards the sun at 16 miles per second, has not brightened since mid-January. This might be the case if the comet is already out of ice particles in its body which melt as the comet moves closer to the sun creating a long, bright tail. Another theory is that the comet is covered in a layer of dust that snuffs out water vapor and other gasses that brighten the comet. Recent quotes from astronomers don’t hold out much hope and include such words as “Comet ISON has been on a standstill for more than 132 days” and “the future of comet ISON does not look bright”. Comet ISON was supposed to put on a spectacular show late this year as it is due to pass about 724,000 miles from the sun on November 28th. This relatively close pass was expected to create a massive tail that some scientists had predicted would even be visible in daylight.
The forecast should start firming up a bit in the near future. Comet ISON — whose nucleus is thought to be just 3 to 4 miles (4.8 to 6.5 km) wide — is slated to cross the "frost line" within the next few weeks, scientists say. This boundary, which lies about 230 to 280 million miles (370 to 450 million km) from the sun, marks the point at which ISON's water ice will start boiling off into space. (Until now, most of its activity has been driven by sublimating carbon dioxide.) ISON should brighten as it crosses the frost line, and scientists and skywatchers should get a better idea of how tough the comet is, researchers say. Some inbound comets haven't survived their trip past the frost line.
Throw in the Phillies season with the comets and the bugs and there certainly have been some disappointments this year.
[Image below of Comet ISON captured in early May by the Hubble Space telescope courtesy of NASA]