[meteorite-list] Asteroid Flyby Not Too Close
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:46:25 2004
Asteroid Flyby Not Too Close
By John Fleck
May 26, 2001
Astronomers are tracking an asteroid making a close pass by Earth this
weekend, and Albuquerque-area stargazers will have the chance tonight to see
it for themselves.
The asteroid became doubly interesting this week after observations by a
team at NASA's Jet Propulsion Laboratory found the 2-mile-wide space rock
has a smaller "moon" orbiting around it.
The asteroid will be at its brightest this evening, according to Kevin
McKeown of The Albuquerque Astronomical Society.
It made its closest approach to Earth on Friday, according to Brian
Marsden of the International Astronomical Union.
It was 3 million miles from Earth - 12 times farther than the distance to
While that might seem far on human distance scales, it is extraordinarily
close in astronomical terms - just one-thirtieth the distance between Earth
and the sun.
It is not unusual for asteroids to come this close to Earth. It happens
several times a year.
But it is unusual for one to be this bright and easily visible to
astronomers, said McKeown.
Marsden said there is no chance the asteroid could hit Earth.
The asteroid's close approach coincides with the society's first
Astronomy Night of the season. That means the public has a chance to peer
through one of the organization's telescopes to see it, said Astronomical
Society member Brock Parker.
The asteroid is not visible to the naked eye, but through a telescope it
looks like a bright point of light moving against the background of the
stars, said McKeown, who has been watching it all week.
"You could actually see it move through the star field," McKeown said
after a night watching the object earlier this week.
The asteroid, known as 1999 KW4, was discovered by New Mexico
Astronomers using an Air Force telescope at the north end of White Sands
Missile Range found it in May 1999 during a routine asteroid hunt.
McKeown's Albuquerque Astronomical Society Colleagues will be sharing
their telescopes with the public this evening, weather permitting, to see
the asteroid and interesting stars and planets.
The viewing, at Oak Flat picnic area in the Manzano Mountains, begins
after sunset, which comes at 8:12 p.m.
The asteroid is in a perfect spot in the sky for easy early evening
viewing, as it moves through the constellation of Ophiucus, the Serpent
"As soon as it gets dark, it'll be high enough to be visible to people at
Oak Flat," McKeown said.
With advance warning that 1999 KW4 would be close to Earth this month,
National Aeronautics and Space Administration scientists set up a special
observing campaign to study it.
The scientists bounced radar signals off the asteroid, using giant radio
telescope antennas in California and Puerto Rico to watch the results.
Their observations, carried out Monday, Tuesday and Wednesday, revealed
not one but two objects orbiting one another, according to Steven Ostro of
NASA's Jet Propulsion Laboratory.
Observations by Czech astronomer Peter Pravec offered "a hint of the
possibility" that 1999 KW4 was not one rock but two.
But until they trained their radar on it the scientists could not be
sure, Ostro said Friday in a telephone interview from Puerto Rico, where he
was carrying out the asteroid observations using the Arrecibo radio
Ostro and his colleagues reported that the smaller of the two is about a
third the size of the main asteroid.
The scientists plan to continue bouncing radar off of the asteroid all
weekend, he said, allowing them to create a detailed three-dimensional
"If there are craters, we will see them," he said.
The asteroid is on an unusual orbit that takes it around the sun every
188 days, meaning it crosses the path of Earth's orbit roughly twice a year.
But orbital calculations show it will not come this close to Earth again,
"This is as close as it comes," he said.
Received on Sun 27 May 2001 02:08:39 PM PDT