Space Rock 2009 DD45 Buzzes Earth
Sky
and Telescope by Kelly Beatty, March 1, 2009
Late word out of the IAU's Minor
Planet Center: a small asteroid will pass close to Earth tomorrow (March
2nd) at 13:44 Universal Time. How close? The MPC's Timothy Spahr
calculates that it'll be 0.00047 astronomical unit from Earth's center.
That's only about 40,000 miles (63,500 km) up — well inside the Moon's
orbit and roughly twice the altitude of most communications satellites!
This little cosmic surprise,
designated 2009 DD45, turned up two days ago as a 19th-magnitude blip in
images taken by Rob McNaught at Siding Spring Observatory in Australia.
It was already within 1˝ million miles of Earth and closing fast.
Observers Rob McNaught (left) and Gordon Garradd strike
an unusual pose — during daylight — at Siding Spring Observatory in
Australia.
Thankfully, the news media have
become less sensationalistic when it comes to these asteroidal close
calls — especially since
one actually struck our planet last October 7th, at night, and the
impact went virtually unnoticed.
So why post this? Well, we figured
someone might want to watch it zip by at up to a half degree per minute!
Even though it's small, likely no more than 100 feet (30 meters) across,
it'll brighten to magnitude 10˝ at its closest — easily within reach of
an 8-inch backyard telescope. That's the good news.
The bad news is that the point of
closest approach occurs over the Pacific somewhere west of Tahiti, so
the most likely viewers are in Australia, Japan, and maybe Hawaii. Sure,
you could look before or afterward, but it'll be brighter than 13th
magnitude only for a few hours.
If you want to give it a try anyway,
you'll need to generate an ephemeris
of positions for your specific location, due to the wide parallax of an
object so close to Earth. And if you manage to spot it, be sure to add a
comment below to let us know.
By the way, this isn't the closest "near-miss" asteroidal fragment on
record. According to the MPC,
tiny 2004 FU162 skirted just 4,000 miles from us on March 31, 2004.
|
Another Warning Out of
the Blue—and Black
A
small asteroid, big enough to wipe out greater London, was
discovered only a couple of days before it was due give us a celestial
bullet burn on March the 2nd 2009. While 64 000 km may sound
like a sizeable distance here on Earth, an object travelling in
excess
of 12 km per second, could cover that gap in about an hour and a half.
The space rock, innocuously dubbed the 2009 DD45, with a diameter of
about 115 feet (30meters) was roughly the same size as the
Tunguska event of 1908 which hit with the force equivalent of 1000
Hiroshima bombs. This new observation was the latest in series of
incidents involving meteors. On February 15 in broad blue daylight, a
streaking fireball was caught on camera over Texas, creating a sonic
boom, and that was thought to be only a meter wide.
 In Canada on the 21st of November 2008 another pyrotechnic
display was captured on video scaring the Dickens out of witnesses; and
last October 7th a meteorite was tracked and exploded in the
atmosphere with the force of a nuclear device over the Sudan. So how
many warnings do we need before this threat is taken seriously enough to
be given a red flag priority as a clear and present danger?
Funding for asteroid research perpetually takes a back seat because of
more obvious, and perpetual down to Earth crisis. Do we have to wait
until disaster strikes, like we did with the 2004 Asian Tsunami, when
for comparatively little cost in preventative measures we could have
saved tens of thousands of lives?
Governments cannot justify precedence in searching for long-odds
space boulders with tax payer money with so many home grown issues to
deal with, and astronomers need help from the private sector if we are
to find these meteors in time to do something about them.
Another factor which is misleading to the general public is that when
these large ‘shooting stars’ occur, they are often reported as
once-in-a-lifetime
celestial fireworks. Eyewitnesses are deemed lucky to have seen the
event and few appreciate that they were lucky the meteorite wasn’t just
a few meters wider.
But forget the doom and gloom of this prediction for a minute because,
unlike earthquakes, volcanoes and hurricanes, this in fact is the one
and only natural phenomena we can
actually prevent—
providing we have the foresight and time to act.
|
