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Big asteroid to be close enough for binoculars

'Flybys like this happen every 50 years or so'

Anticipated sky path of asteroid 2002 NY40 during four hours of its upcoming August 18 fly-by
Anticipated sky path of asteroid 2002 NY40 during four hours of its upcoming August 18 fly-by  

By Richard Stenger

(CNN) -- An asteroid about a half mile (800 meters) across will soon pass close enough to Earth to observe with a small telescope or binoculars, astronomers said.

The space rock, 2002 NY40, is not to be mistaken for 2002 NT7, another newly discovered asteroid that generated headlines last month when scientists briefly mused that it would smack into our planet in 2019.

Further observations showed it almost certainly won't, nor will 2002 NY40, which later this month will glide to within 330,000 miles (530,000 km), slightly farther than the distance of the moon.

For the first half of this month, 2002 NY40 will hardly change its position in the sky in the constellation Aquarius, a sign that the asteroid is heading in our direction.

The big boulder will gradually creep north. On August 16, it will really begin to pick up its northerly pace. Two days later it will make its closest swing by Earth and be at its brightest, astronomers said.

NASA animation of 2002 NY40's projected orbit  (Browser must be Java enabled)

At the time, 2002 NY40 will be visible with strong binoculars or small telescopes. It will be 16 times dimmer than the faintest star visible with the naked eye, but for an asteroid, it is quite a shiner.

"Flybys like this happen every 50 years or so," said NASA's Don Yeomans, who manages the space agency's Near-Earth Object Program at the Jet Propulsion Laboratory in Pasadena, California.

"Asteroids are hard to see because they're mostly black like charcoal. We don't know yet what this asteroid is made of but we'll have a much better [idea] by the end of August," he said in a statement.

On the night of closest approach, 2002 NY40 will glide by Vega, one of the brightest stars. Sky watchers in the Southern Hemisphere will not have a good view.

2001 radar image of another asteroid, 1950 DA
2001 radar image of another asteroid, 1950 DA  

For North Americans, the best time to watch will be in the evening on August 17. For Europeans, it will be best to look up in the predawn hours of August 18.

During the flyby, the asteroid will move every four minutes the same distance in the sky as the diameter of the moon. Soon afterward, its unlit side will face our planet and the asteroid will quickly dim, astronomers said.

Scientists plan to make the most of the close encounter. Some will look at its reflected light spectrum to figure out its chemical makeup. Others will "ping" it with radio waves and study it with the giant Arecibo radar dish in Puerto Rico.

Besides making three-dimensional maps, the radar observations can help determine whether the asteroid, whose orbit ranges from the inner solar system to the asteroid belt between Mars and Jupiter, will pose a threat to Earth in the future.

"At present, we know there's little risk of a collision with 2002 NY40 for decades," said Jon Giorgini, a JPL radar researcher. Afterwards, "we'll be able to extrapolate the asteroid's motion hundreds of years in the past and into the future."

Astronomers first spotted the space rock on July 14, using the one-meter LINEAR (Lincoln Near Earth Asteroid Research) telescope in New Mexico.




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