[meteorite-list] Close but no strewn field

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Mon, 02 Mar 2009 11:56:51 -0500
Message-ID: <lm3oq4haf7l34gu10jh1gmuhkndfoo4dvh_at_4ax.com>

http://www.itwire.com/content/view/23553/1066/

Look up in the sky! 2009 DD45 is flying by!
by William Atkins
Tuesday, 03 March 2009

No, it?s not a bird, a plane, or even Superman. But, on Monday, March 2, 2009,
the Asteroid 2009 DD45 will be passing by Earth at only 63,500 kilometers away.
That's pretty close to Earth and us living things down here on terra firma.

According to SpaceWeather.com, the closest approach of Asteroid 2009 DD45 to
Earth is at 5:40 a.m. Pacific Standard Time (PST), or 1340 Universal Time (UT),
on March 2, 2009.

But, that means ... oops, it?s already past us.

It's already passed us out there in outer space because astronomers only learned
about this newly discovered asteroid a couple of days ago.

So, it has already flown by Earth at its closest approach.

Any danger that may have occurred because of the closeness of the asteroid to
Earth has also already passed. And, astronomers confirm there wasn't any danger
to Earth and its residents.

However, even after that day,the asteroid will be visible with telescopes used
by amateur and professional astronomers.

The distance between Earth and Asteroid 2009 DD45 was estimated from between
72,000 to 63,500 kilometers (about 40,000 miles), or well inside the orbit of
the Moon to Earth.

Astronomers call this distance about 0.00047 AU (astronomical unit), or a very
small fraction of the average distance between the Sun and the Earth.

SpaceWeather.com says, ?That?s only twice the height of a geostationary
communications satellite.?

In other words, that?s pretty close for a ?near-miss? of an asteroid to the
Earth.

Whew! As secret agent man (and part-time astronomer) Maxwell Smart would say,
?Missed it by that much!?

Scotish-Australian astronomer Rob H. McNaught (from the Research School of
Astronomy and Astrophysics, Australian National University)?while searching the
sky from inside the Siding Spring Observatory in Australia?found the asteroid
only a few days ago.

At that time, McNaught discovered the asteroid while it was only about 1.5
million miles from the Earth and shining like a 19th magnitude star. [Sky and
Telescope: ?Space Rock 2009 DD45 Buzzes Earth?]

The asteroid is about 30 to 40 meters (about 100 feet) in diameter, which is
about the same size as the Tunguska object (comet, asteroid, or meteor) that
impacted the Soviet Union?s Siberia near the Podkamennaya Tunguska River in
1908.

The Science at NASA article ?The Tunguska Event--100 Years Later? states, ?It is
estimated the asteroid entered Earth's atmosphere traveling at a speed of about
33,500 miles per hour. During its quick plunge, the 220-million-pound space rock
heated the air surrounding it to 44,500 degrees Fahrenheit.?

Then, ?At 7:17 a.m. (local Siberia time), at a height of about 28,000 feet, the
combination of pressure and heat caused the asteroid to fragment and annihilate
itself, producing a fireball and releasing energy equivalent to about 185
Hiroshima bombs.?

Again, the size of Asteroid 2009 MM45, as with the Tunguska object, has the
potential to produce devastating effects here on Earth.

It?s happened once, it can happen again.

However, amateur astronomers will be able to see and photograph Asteroid 2009
DD45 as it travels through the constellations Hydra and Virgo.

They will need at least an eight-inch backyard telescope to see it as it zips
past at up to 0.5 degree per minute.

At its peak brightness, which will only last a few hours, the asteroid will
shine similar to a 13th magnitude star, but immediately afterwards it will be
about a 10.5 to 11th magnitude star.

Its closest point to the surface of Earth was predicted to be over the Pacific
Ocean near Tahiti.

Thus, skygazers near Tahiti, such as in Australia, eastern Asia, Hawaii, Japan,
and New Zealand, will get the best chance to see the asteroid flying across the
sky.

Check out the orbital parameters of Asteroid 2009 DD45 on the NASA Jet
Propulsion Laboratory?s Small-Body Database: ?(2009 DD45).?

The Earth has several near-earth asteroid tracking systems. One of them is at
NASA?s Jet Propulsion Laboratory, in Pasadena, California. It is called NEAT,
for Near Earth Asteroid Tracking.

If we only learned about Asteroid 2009 DD45 a few days ago and it could have
smashed into Earth (if its flight path was only different by a little bit),
wouldn?t this be a good reason for us Earthlings to beef up, just a wee little
more, our tracking systems for asteroids and other near-Earth objects.

It seems that this might be the prudent thing to do!

What do you think?
Received on Mon 02 Mar 2009 11:56:51 AM PST