I’m actually deep in the Southern Hemisphere right now, searching for Comet ISON. I’m leading a group of 88 people into the Atacama Desert of Chile, where the heavens are deep blue by day and inky black by night. Adjoining this desert, we have hired an entire mountaintop observatory under these astounding skies, to see if we can be among the first to glimpse this already-famous comet. Here is my first report:
You’ve heard the hype that Comet ISON will be the greatest comet of the century. Maybe you’ve also heard the anti-hype that the comet is totally fizzling out. The truth is that comets, especially first-time visitors to the inner solar system like this one, are notoriously unpredictable. We can always calculate where a comet will be, but not how bright it will become. Everything depends on how its ices and imbedded dust particles react with the Sun as it approaches.
We do know that ISON is headed directly toward the Sun. It will narrowly skim over the fiery gaseous surface on Thanksgiving, passing just one Sun-width above its blazing photosphere. Then, if it survives this perilous perihelion passage, it should be absolutely beautiful the first week of December, standing just above the western horizon after sunset. An unobstructed sunset view is all that’s needed. With any luck, its tail will splay upward into a long gorgeous arc. And although it will come closest to Earth weeks later, on December 26 – missing us by about 40,000,000 miles, or about the nearest that Mars ever gets – it will already be dimmer by then.
We are trying to catch it now, before perihelion. It’s a balancing act. Moonlight is the enemy of comets, and the Moon unfortunately waxes during the last half of November. Thus, we are here under ideal skies now, before the Moon brightens.
For the moment, ISON seems one or two magnitudes dimmer than the earliest estimates. But that’s still pretty good. We expect to be able to see it with binoculars as it brightens from eighth to sixth magnitude during our 17 days here.
If you want to check it out yourself, you needn’t budge. You don’t need to be in South America. The comet was just an excuse to bring people to these amazing skies. If you live away from all light pollution and know the constellations, gaze eastward just before dawn – meaning at 6 a.m. Sweep binoculars to the lower right of Leo’s tail star Denebola. This will be located one-quarter of the way up the sky, not too low. At eighth magnitude, the comet may be challenging, though its tail is growing nicely. One week from now, try again: The comet should have brightened threefold by then.
I’ll give you weekly reports so you’ll know whether we’re getting a bust, a true spectacle or – most likely – something in between.
Want to know more? To read Bob Berman’s previous “Night Sky” columns, visit our Almanac Weekly website at HudsonValleyAlmanacWeekly.com.