Who, us... vulnerable??
Posted on 07/25/2002 9:34:11 AM PDT by Joe Hadenuf
Next month a newly discovered asteroid will pass close enough to Earth to be easily spotted in small telescopes and even binoculars.
According to calculations by Gareth V. Williams, associate director of the Minor Planet Center in Cambridge, Massachusetts, the asteroid's August 18th flyby should bring it to within 530,000 kilometers (330,000 miles) of Earth, just outside the Moon's orbital distance.
Astronomers first detected this object, designated 2002 NY40, on July 14th with the 1-meter LINEAR telescope in New Mexico. Thus it was picked up a full month before brushing by Earth, unlike asteroid 2002 MN, whose pass well inside the Moon's orbit was not realized until several days after the fact. The best current estimates suggest that this new interloper is about 500 meters (0.3 mile) across — significantly larger than 2002 MN.
Still quite faint at magnitude 18, 2002 NY40 is making a very tight loop around the star Beta Aquarii. During the next few weeks it will brighten tremendously and yet remain almost motionless in the sky — the eerie signature of an asteroid hurtling right toward Earth!
On the night of Saturday, August 17th, 2002 NY40 should reach magnitude 9.3 when well placed for viewing from North America. At that time its angular velocity will exceed 4 arcminutes per minute, a motion easily perceptible in small telescopes. Sky & Telescope plans to issue detailed observing instructions, through AstroAlerts and SkyandTelescope.com, in the days leading up to this rare event.
A mere 24 hours after it goes by, the asteroid plunges hopelessly beyond reach of Earth-based telescopes as it heads closer to the Sun. (We will then be viewing its unilluminated side, which explains why it becomes so faint, so fast.)
While there is no danger of 2002 NY40 striking Earth during this flyby, a future impact has not been ruled out. Both NEODyS, operated by the University of Pisa, and NASA's Near-Earth Object Program have identified a number of very close encounters in the years to come. These occur either around August 18th as the asteroid heads in toward the Sun, or near February 14th when on its way out. Both agencies are focusing on a flyby just 20 years from now (on August 18, 2022), when there appears to be a 1-in-500,000 chance of an impact — extremely unlikely, but worrisome just the same.
Meanwhile, professional astronomers are gearing up to make the most of this encounter. "2002 NY40 is a potentially very good radar target," notes Michael Nolan (Cornell University). He urges advanced amateurs to obtain detailed photometry of the asteroid on the nights leading up to the flyby. A good light curve, revealing the object's rotation rate, would help in selecting the radar instrumentation to be used with the 1,000-foot dish at Arecibo, Puerto Rico.
What about the comet impactor experiment? Didn't they do this already, or is it still on the way? Sorry I don't remember which mission it is.
I'm all for continuing with the LINEAR program, but we'll never be able to identify every dangerous object -- there are too many of them that are big enough to hurt but small enough to escape detection. Moreover, the really dangerous ones -- the ones that cross earth's orbit -- have orbits that are forever being perturbed by the inner planets. In some cases, we can't even predict which side of the sun they'll be on 200 years from now!
But you are correct. Someone that doesn't know the sky could have much difficulty.
Klendathu.
Launches January 2004, impact encounter July 2005.
Hey, this is the night of the FRiva awards dinner in Las Vegas. Did JimR arrange the free entertainment somehow?
Well, you found that out by yourself. Slight correction to the mission profile; the satellite will release an impactor (370 kg) that will guide itself to the impact on the comet. The other part of the satellite will observer. The impactor is half copper, which has a distinct spectral signature that can be filtered out of the spectra of the impact debris. The impactor will be traveling 10 km/second; the comet is moving extremely fast too, so this is a high-pressure shot and they only get one chance.
Who, us... vulnerable??
Damned Light Pollution!! There oughtta be a Law...MUD
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