Sabtu, 07 Mei 2011

Giant asteroid heading close to the Earth

Giant asteroid heading close to Earth

A giant asteroid weighing 55 million tonnes will just miss the Earth later this year, Nasa experts have predicted. 

 Asteroid collision

The rock, which is quarter of a mile across, will pass between our planet and the moon in November and will be visible with small telescopes.
Robin Scagell of the Society for Popular Astronomy said: “It’s rare we get the chance to see an asteroid up close.”
If it were to hit the earth, the asteroid, named YU55, would have an impact equivalent to 65,000 atom bombs and would leave a crater more than six miles wide and 2,000ft deep.
Passing by at a distance of just 201,000 miles, the asteroid will be the largest object ever to approach the earth so close.
Nasa has officially labelled it a Potentially Hazardous Object, but have stressed there is no danger of impact while on its current course.

YU55 orbits the sun every 14 years and last passed the earth in April 2010 at a distance of 1.5 million years.
There are currently 874 near earth asteroids which are considered to be potentially dangerous.
They are closely monitored and the list is being constantly added to as astronomers discover new objects in near space.
Scientists estimate that there is usually one large collision with earth every few hundred thousand years.

Asteroid Sebesar Pesawat Melintasi Bumi

INILAH.COM, California - Para astronom menyiapkan alat guna mengamati asteroid raksasa seukuran pesawat. Asteroid ini akan melintasi bumi dengan jarak sangat dekat. Seperti apa? melaporkan, sebuah asteroid seukuran pesawat akan melintasi bumi dengan jarak lebih dekat dari bulan. Namun media itu memastikan, asteroid itu tidak berpotensi mengancam Bumi.
"Tak ada bahaya tabrakan saat asteroid 2005 YU55 mencapai jarak terdekat dengan bumi 8 November mendatang,” ungkap para astronom itu.
Jarak terdekat lintasan asteroid ini diperkirakan mencapai 324.604 kilometer dari Bumi, lanjutnya.
Pada titik terdekat itu, para astronom mengaku menjadi bisa mempelajari asteroid tersebut dengan lebih baik.
“Biasanya, obyek angkasa yang melintasi Bumi berjarak cukup jauh. Namun, dengan jarak sedekat ini, perangkat sains di Bumi bisa mengamati dengan baik,” papar ilmuwan Jet Propulsion Laboratory milik NASA Barbara Wilson, di Pasadena, California.
Asteroid 2005 YU55 ditemukan para astronom University of Arizona di Tucson pada 2005.

Sky-watchers in Asia, Australia, and the Pacific islands welcomed a surprise guest Monday: an asteroid that passed just 41,010 miles (66,000 kilometers) above Earth. Discovered only days ago, asteroid 2009 DD45 zipped between our planet and the moon at 13:44 universal time (8:44 a.m. ET). The asteroid was moving at about 12 miles (20 kilometers) a second when it was closest to Earth.

"We get objects passing fairly close, or closer than this, every few months," Timothy Spahr, director of the International Astronomical Union's Minor Planet Center in Massachusetts, said in an email.
"Also, though, note these are only the ones that are discovered. Many more pass this close undetected"—as asteroid 2009 DD45 nearly did.
Astronomers didn't notice the oncoming asteroid until February 28, when it showed up as a faint dot in pictures taken at the Siding Spring Observatory in Australia.
At that point the asteroid was already a mere 1.5 million miles (2.4 million kilometers) from Earth, and closing in fast.
(Related: "Undetectable Asteroids Could Destroy Cities, Experts Say.")
Asteroids are rocks that generally range from a few feet to several miles in diameter. In our solar system most asteroids orbit the sun in the asteroid belt between Mars and Jupiter.

Asteroid to Buzz Earth Again?
At just 65 to 164 feet (20 to 50 meters) wide, the asteroid "was much fainter than anything visible to the naked eye" even during close approach, Spahr said.
But on Monday observers using backyard telescopes were able to track the asteroid speeding through the constellation Virgo for at least a few hours after the object's closest approach.
According to Spahr, amateur astronomers contributed to the center's monitoring efforts by sending in measurements, which are helping to refine calculations of the asteroid's orbit.
Thanks to data from Siding Spring, other observatories, and amateurs, the orbit for 2009 DD24 is "very well determined now," he said. Astronomers now know that the asteroid is moving within the inner solar system and that the space rock completes an orbit around the sun every 1.56 years.
This means the asteroid could swing close by Earth again someday—though that doesn't seem to be any cause for alarm, if Monday's flyby is any indication.
"As far as we know," Spahr said, "nothing unusual happened."

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