From: LARRY KLAES (email@example.com)
Date: Thu Aug 01 2002 - 12:45:10 PDT
----- Original Message -----
Sent: Tuesday, July 30, 2002 12:34 PM
Subject: Look At That Asteroid (2002 NY40)
Look at that Asteroid
NASA Space Science
A big space rock will soon come so close to Earth that sky watchers can see
it through binoculars.
July 30, 2002: Relax, there's no danger of a collision, but it will be close
enough to see through binoculars: a big space rock, not far from Earth.
Astronomers discovered the nearby asteroid, named 2002 NY40--not to be
confused with better-known 2002 NT7--on July 14th. It measures about 800
meters across, and follows an orbit that ranges from the asteroid belt to
the inner solar system. On August 18th, the asteroid will glide past our
planet only 1.3 times farther away than the Moon.
"Flybys like this happen every 50 years or so," says Don Yeomans, the
manager of NASA's Near-Earth Object Program office at JPL. The last time
(that we know of) was August 31, 1925, when another 800-meter asteroid
passed by just outside the Moon's orbit. In those days there were no
dedicated asteroid hunters--the object, 2001 CU11, wasn't discovered until
77 years later. At the time of the flyby, no one even knew it was happening.
2002 NY40 is different. We know the asteroid is coming, and astronomers have
time to prepare.
One team of observers led by Mike Nolan at the giant Arecibo radar in Puerto
Rico will "ping" 2002 NY40 with radio waves as it approaches Earth. Such
data result in impressive 3D maps of asteroids, which have often surprised
astronomers with their weird shapes. Some prove to be binary systems (one
space rock orbiting another) and one even looks like a dog bone.
"Radar data will also improve our knowledge of the asteroid's orbit," adds
Jon Giorgini, a member of the radar team from JPL. "At present, we know
there's little risk of a collision with 2002 NY40 for decades. When the
Arecibo radar measurements are done, the orbit uncertainties should shrink
by more than a factor of 200. We'll be able to extrapolate the asteroid's
motion hundreds of years into the past and into the future, too."
2002 NY40 is faint now. It shines by reflected sunlight like a 17th
magnitude star. As it nears Earth, however, the space rock will brighten,
soaring to 9th magnitude on August 18th. That's about 16 times dimmer than
the dimmest star you can see without a telescope. But as asteroids go, it's
"Asteroids are hard to see," explains Yeomans, "because they're mostly black
like charcoal. The most common ones--carbon-rich C-type asteroids--reflect
only 3% to 5% of the light that hits them. Metallic asteroids, which are
somewhat rare, reflect more: 10% to 15%."
"We don't know yet what this asteroid is made of," he continued, "but we'll
have a much better idea by the end of August." Astronomers using
ground-based telescopes will have little trouble recording the asteroid's
spectrum and thus its composition.
On the date of closest approach, the asteroid will sail past Vega, the
brightest star in the evening summer sky. Sky watchers with powerful
binoculars or small telescopes can see it--a speck of light moving 8 degrees
per hour. (Note: The flyby will be visible mostly from Earth's northern
hemisphere; this is not a good opportunity for southern sky watchers. North
Americans can see it best after sunset on Aug. 17th; Europeans should look
during the hours before dawn on Aug. 18th.)
Something extraordinary will happen hours after 2002 NY40 passes Earth: the
space rock will quickly fade.
Asteroids, like moons and planets, have phases. The sunlit side of 2002 NY40
is facing Earth now. It's full, like a full Moon. On August 18th, the
asteroid will cross Earth's orbit on its way toward the Sun. Then the phase
of the asteroid will change--from full to gibbous to half.... finally the
night side will turn to face Earth. The asteroid will grow dark, like a new
It's not every day you can peer through binoculars and see a near-Earth
asteroid--and then see it disappear. But 2002 NY40 has a lot to offer.
"Mother Nature is making it very easy for us to study this one," says
Yeomans. That's good because "we need to know more about near-Earth
asteroids in case we ever need to destroy or deflect one." What are they
made of? How are asteroids put together? These are key questions that 2002
NY40 will help answer.
"Don't forget," adds Yeomans, "most asteroids pose no threat to Earth. But
they do contain valuable metals, minerals and even water that we might tap
in the future." When such asteroids come close (but not too close!) we have
relatively easy access to them--both to study and, one day perhaps, to
Or, to paraphrase Nietzsche, asteroids (like 2002 NY40) that do not hit us,
make us stronger.
For more information about 2002 NY40, including an up-to-date ephemeris for
sky watchers, please visit JPL's Near-Earth Object Program web site:
3D Orbit Simulation:
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