PLEASE NOTE:
*
CCNet 81/2003 - 2 October 2003
DOUBTS ABOUT NASA'S 'FIREBALL' INTERPRETATION
----------------------------------------------
A schoolboy has impressed experts at American space agency Nasa
after capturing a
rare picture of a meteor burning out above his home town in south
Wales. He took
two photographs of the fiery ball before it burned out and rushed
home to show
his parents. Later, he emailed the picture to Nasa asking for an
explanation and
was amazed to discover that the space experts were so impressed
with his snap they
had published it on their website.
--BBC News Online, 1 Oct. 2003
No reports of such an event have been received by the BAA (we get
to hear
about these pretty quickly, often at the rate of once a week and
more!).
Identification of this image as a fireball seems a bit doubtful
to me, sorry!
--Neil Bone, Director, BAA Meteor
Section, 1 Oct. 2003
I don't think for a moment that there was any connection [of 2003
SW130]
with the Orissa meteorite, which, after all, fell a good week
after the
asteroid's pass. Coming to within some 160,000 km of the earth,
SW130 made
the sixth closest approach known for an asteroid. Actually, it
was then the
fifth closest approach, for we now have 2003 SQ222, which came to
a record
close distance of 90,000 km -- just a few hours after the
meteorite. But
again, I strongly doubt any connection, and SW130 and SQ222,
though both
probably smaller than 10 meters across, themselves have very
different orbits.
--Brian Marsden, Minor Planet Center, 1
Oct. 2003
(1) DOUBTS ABOUT NASA'S 'FIREBALL' INTERPRETATION
(2) THE SKY ISN'T FALLING, BUT PIECES SURE ARE
(3) SCHOOLBOY'S PHOTO AMAZES NASA
(4) COMET DEBRIS CITED AS FIREBALL METEOR SEEN MONDAY OVER THE
SOUTH BAY
(5) SEPT. 29 FIREBALL OVER NORTHERN FRANCE
(6) GSI SCIENTIST CLAIMS METEORITES "CREATED DEEP CRATERS
WHERVER THEY FELL"
(7) TWO MORE PIECES OF METEORITE FOUND IN ORISSA
(8) IS THERE AN ORISSA CONNECTION?
(9) NO CONNECTION BETWEEN ASTEROIDS AND METEORITES
(10) TIME OF 'FIREBALL' EVENT OVER SOUTH WALES
(11) PEGASUS A FALL REFERENCE POINT TO LOCATE AND VIEW COMET
ENCKE
==========
(1) DOUBTS ABOUT NASA'S 'FIREBALL' INTERPRETATION
Neil Bone <bafb4@central.susx.ac.uk>
Dear Benny,
Having been prompted to look at this by John Mason
(Assistant Director, BAA Meteor Section), I'm more thana wee bit
doubtful as to the nature of what's shown! It looks, to me, more
like a
sunlit contrail, with the setting Sun off to the right from the
frame
(hence that end is bright). In the image taken few minutes later,
the Sun
has set further and is no longer illuminating the end of the
trail. I
would be surprised if the image caught the exact end, as implied
by the
lack of any continuation of the 'residual trail' beyond its
earlier
extent, which further leads me to believe that this wasn't a
fireball.
No reports of such an event have been received by the BAA (we get
to hear
about these pretty quickly, often at the rate of once a week and
more!).
Identification of this image as a fireball seems a bit douibtful
to me,
sorry!
Neil Bone
Director, BAA Meteor Section
=========
(2) THE SKY ISN'T FALLING, BUT PIECES SURE ARE
Space.com, 1 Oct. 2003
http://www.space.com/scienceastronomy/chicken_little_031001.html
By Robert Roy Britt
A host of mostly coincidental recent events make Chicken Little
sound ever-so-slightly more credible. In the past eight days,
stuff falling from space rocked a village in India and a bathroom
in Louisiana, while lighting up the skies over the San Francisco
Bay area, Europe and Australia.
The most spectacular visitor from beyond was a meteorite
initially said to set a village afire in India and injure 20
people this past weekend. Later reports by the BBC and elsewhere
put the injuries at three.
The fireball streaking through the sky turned night into day,
witnesses said. It was reported visible across a nearly
5,800-square-mile (15,000-square-kilometer) region. Two pieces
about 11 pounds each (5 kilograms) were said to be recovered.
On Monday, Sept. 29, a bright fireball startled residents around
San Francisco. Witnesses said it flared several times over a few
seconds before disappearing below the horizon, according to a
report in the San Jose Mercury News.
"It's by far the brightest and longest I've ever seen,''
said Jake Burkart, an amateur astronomer who said he'd been
watching shooting stars since his youth. "It was really
amazing.''
Peter Jenniskens, an astronomer with the SETI Institute and
NASA's Ames Research Center, told the newspaper that the event
had the markings of comet debris, which is more fragile than
asteroid material and therefore more likely to break apart and
generate a bright flare.
The object may have landed in the ocean, Jenniskens said.
Jenniskens said the fireball might have been part of an
unexpected shower of debris. Another bright meteor had been
spotted five hours prior from Europe, he said.
Another bright and fiery object was seen in the night sky over
Australia this past weekend, near the time of the Indian
meteorite. No connection between the two has been made. An
official in Australia said, however, that manmade space junk may
have caused the curious event spotted from south of Queensland.
Space rocks frequently strike Earth's atmosphere. They are called
meteors when streaking into the ever-denser air, where most
vaporize. While in space they might be referred to as asteroids
if they are large, or meteoroids if they are small. If they hit
the ground, they're called meteorites.
Most of the smaller pieces light up fantastically, as shooting
stars or fireballs, and never reach ground. It is not uncommon
for residents of a particular region to be surprised or even
shocked by a fireball, as space debris rains down on Earth daily.
Many visible shooting stars start out as bits no larger than a
sand grain. It only takes a pea-sized object to generate a
brilliant fireball. And even something the size of a Volkswagen
can disintegrate before reaching the surface.
One that did not fully vaporize hit Roy Fausset's recently
renovated bathroom Sept. 23 in New Orleans.
Fausset returned from work to find holes in his roof and two
floors. A space rock was in a crawl space under the house.
"The powder room door was open and it looked like an
artillery shell had hit the room," he told the Associated
Press. Tests by Tulane University researchers suggest the object
indeed came from space.
"I'm in shock," Fausset told the Associated Press.
"Oh, that's scary. I will certainly go to church this
Sunday, because the Lord was certainly sending me a
message."
There are no known deaths by meteorites. But a few people have
been injured throughout history, and a space rock killed a dog in
Egypt in 1911. Of greater concern, astronomers say, are large
asteroids that could devastate a region. None are known to be on
a collision course with Earth, but astronomers are keeping a wary
eye.
Copyright 2003, Space.com
===============
(3) SCHOOLBOY'S PHOTO AMAZES NASA
BBC News Online, 1 Oct. 2003
http://news.bbc.co.uk/2/hi/uk_news/wales/south_east/3155928.stm
A schoolboy has impressed experts at American space agency Nasa
after capturing a rare picture of a meteor burning out above his
home town in south Wales.
Jonathan Burnett, 15, was taking snaps of his friends performing
skateboarding stunts near his home in Pencoed near Bridgend when
a bright light in the sky caught his attention.
He took two photographs of the fiery ball before it burned out
and rushed home to show his parents.
Later, he emailed the picture to Nasa asking for an explanation
and was amazed to discover that the space experts were so
impressed with his snap they had published it on their website.
His father Paul explained: "He has a digital camera and was
out taking some pictures of his friends on the street.
"A little boy ran over and shouted 'look the sun has
exploded' and Jonathan turned around and managed to take two
pictures of it.
"None of us knew what it was and we thought that maybe it
was a plane that had exploded.
"We were really keen to find out what it was, and so without
us realising it, Jonathan had emailed the picture to experts at
Nasa to ask for an explanation.
"The next thing we knew that they had used the picture on
their website" he said.
Jonathan, who attends Pencoed Comprehensive School, said:
"It was such a coincidence that we happened to be in the
street at the time.
"I was trying out my new camera to take pictures of my
friend who was doing a skateboarding trick.
Meteor facts
Meteors are caused by debris from a comet burning up in our
atmosphere
When comets pass through space, they leave behind a trail of dust
and ice
These comet fragments will burn up in our atmosphere if the Earth
enters the trail.
From the ground, they look like jets of bright light, shooting
across the sky
"I took the first picture and then about two minutes later I
took the second one before it burned out.
"One of our first thoughts was that it was the sun
reflecting off the clouds.
"Everyone in school is amazed - most of my friends believe
me but there are some who said they don't believe me.
"I am really interested in photography - but I don't think I
will ever manage to take another picture like that," he
added.
On its website Nasa described the teenager's picture as a
"sofa-sized rock came hurtling into the nearby atmosphere of
planet Earth and disintegrated".
"By diverting his camera, he was able to document this rare
sky event and capture one of the more spectacular meteor images
yet recorded. Roughly one minute later, he took another picture
of the dispersing meteor trial.
Bright fireballs occur over someplace on Earth nearly every day.
"A separate bolide, likely even more dramatic, struck India
only a few days ago."
Copyright 2003, BBC
===========
(4) COMET DEBRIS CITED AS FIREBALL METEOR SEEN MONDAY OVER THE
SOUTH BAY
San Jose Mercury News, 1 Oct. 2003
A bright fireball that streaked over the South Bay on Monday
evening may have been debris from a comet, according to an
astronomer.
The meteor -- commonly called a shooting star -- traveled east to
west at 7:57 p.m. Observers said it flared several times from
three to 10 seconds before disappearing over the horizon.
"It's by far the brightest and longest I've ever seen,"
said Jake Burkart, 29, of San Jose, an amateur astronomer who has
been watching shooting stars since he was a child. "It was
really amazing."
Meteors are streaks of light left by bits of space dust as they
enter the upper atmosphere and evaporate. The dust may come from
a rocky asteroid or from a comet, which is a loose conglomeration
of rock and ice.
Peter Jenniskens, an astronomer with the SETI Institute at
NASA/Ames Research Center, said the meteor's appearance is
typical of comet dust, which is more fragile than the dust from
an asteroid and more likely to break up and flare.
Five hours earlier, he said, another bright meteor was seen over
Europe, where it reportedly glowed green or blue, broke into
fragments and left a persistent, shining trail.
"So maybe we have a bit of a shower of bright fireballs
going on at the moment, which is interesting," Jenniskens
said.
Although showers of meteors periodically light up the skies as
the Earth passes through a thick patch of cometary dust, no such
shower was expected on Monday night, he said. The next one,
called the Draconids shower, is supposed to arrive Oct. 9.
Jenniskens said whatever caused Monday's fireball appears to have
landed in the ocean
Copyright 2003, San Jose Mercury News
============
(5) SEPT. 29 FIREBALL OVER NORTHERN FRANCE
Marco Langbroek <marco.langbroek@wanadoo.nl>
posted on IMO-news
Hello all,
From the observations with indications of sky directions I have
so far
(sightings from Leuven in Belgium, Saarland in Germany, Almelo in
the
Netherlands and Loon op Zand in the Netherlands) for the 29
september 21:11
UTC fireball, it appears that it must have been over Northern
France in the
vicinity of Verdun. The reported directions of the endpoint are
reasonably
in agreement with regard to this position. There is one
additional possible
sighting from Tongeren in Belgium, which however nowhere matches
with the
other observations. Perhaps this was another meteor.
With regard to the trajectory direction and entry angle, things
remain a bit
too uncertain although it would appear that the entry angle was
steep as
both observers east of the meteor, north of it and northeast of
it report
steep angles with the horizon.
Two observers report fragmentation near the end, green or blue
colors are
mentioned, and at least one observer reports a persistent train
of long
duration.
- Marco
----------
Marco Langbroek
marco.langbroek@wanadoo.nl
meteorites@dmsweb.org
http://home.wanadoo.nl/marco.langbroek
===========
(6) GSI SCIENTIST CLAIMS METEORITES "CREATED DEEP CRATERS
WHERVER THEY FELL"
Press Trust of India, 1 Oct. 2003
http://www.rediff.com/news/2003/oct/01oris.htm
Orissa villagers, still dazed at the rare sight of a flaming
meteor screaming across the night sky of September 27, stumbled
upon more debris even as the Geological Survey of India said the
rock-like materials found in Kendrapara district were
extra-terrestrial objects.
Unusual looking objects were recovered from two villages of the
district, Sanamarichapalli under Rajnagar police station and
Subarnapur under Pattamundai police station, on Tuesday morning,
official sources said.
The objects are solid and rock-hard, have a black exterior while
broken pieces are grey in colour. They were found in unmanned
areas and the two largest weighed over three kg each.
Villagers of Paschima Suniti and Benakanda villages had found
such objects in paddy fields within hours of sighting the
fireball shooting across the sky dazzling at least 11 Orissa
districts.
Dr K C Sahu, senior GSI scientist who had arrived in Kendrapara
on Monday, said the rocks had created deep craters wherever they
fell.
The villagers are depositing the debris with the police at
Rajnagar and Pattamundai. The latter have been instructed by the
district authorities to hand the debris over to the emergency
wing of the collectorate.
According to Dr Sahu, the objects would be taken to the GSI's
well-equipped laboratory in Bhubaneswar on Wednesday and later to
the organisation's headquarters in Kolkata for scientific study.
Sahu revealed that remains of meteorites found elsewhere in the
nation were kept in Kolkata's National Museum.
© Copyright 2003 PTI. All rights reserved.
===========
(7) TWO MORE PIECES OF METEORITE FOUND IN ORISSA
The Times of India, 2 Oct. 2003
http://timesofindia.indiatimes.com/cms.dll/html/uncomp/articleshow?msid=212496
KENDRAPADA: Two more pieces of meteorite were found on Monday in
Kendrapada district by the villagers of Sanamarichi of Rajanagar
block and Subarnapur village of Pattamun-dai block.
On Sunday, the seaside villagers of Pashimasuniti and Barakanda
under Mahakalapada block, too, had re-trieved two pieces of
meteorite.
All the four pieces of rare objects from space are now kept in
the office of the Kendrapada district collector.
Scientists of the Geological Survey of India visited all the four
places and collected soil samples from the spots. The meteorite
may have fallen from Mars and the GSI scientists will examine
those in Kolkata, stated senior geologist Monoranjan Mohanty. He
added that for the first time a meteor-ite had fallen in Orissa.
Though around 90 per cent of the meteorite get lost in the sea or
in re-mote places, villagers were alert enough to retrieve the
four pieces of the rare object in the coastal district of
Kendrapada this time.
The GSI scientists have also collected soil samples from places
where the pieces of meteorite had fallen.
Many villagers have even stolen some small pieces of the
meteorite for which the district administration has directed the
police to recover those pieces from them.
Moreover, with people from the district and other places scouting
around for some pieces of the meteorite, the police are not
allowing these people to visit these areas, said
inspectorin-charge of Pattamundai police station Bauribandhu
Behera.
State museum official Umakanta Mohanty has also visited the
spots. He told TNN that the museum must pre-serve the rare
objects.
He further stated that as the GSI will take away the meteorite
from the state, the people of Orissa will be deprived. Mohanty
though claimed that GSI was the only legal custodian of the
meteorite and the museum officials had no right on these pieces.
He emphasised that science will certainly prevail over people's
sentiments.
Dictrict collector Hemant Sharma stated that it will give away
the four pieces of meteorite to a government agency once the
state government gives the go-ahead.
(Ashis Senapati)
Copyright 2003, The Times of India
=========== LETTERS ============
(8) IS THERE AN ORISSA CONNECTION?
Andy Smith <astrosafe22000@yahoo.com>
Hello Benny and CCNet,
In our search for possibly related events to the
Orissa (India) impact on 27 September, we noticed the
discovery of NEO 2003SW130 by SPACEWATCH (SW). Arianna
Gleason first noticed it on the 20th and she and Tom
Gehrels then followed it for several nights and
obtained additional measurements from the Klet and the
VLT. Brian MArsden and the MPC team were working with
them, all the way. What terrific teamwork and
cooperation. Just the spirit we are all looking for.
Bravo.
This happens to be the smallest NEO ever detected by
the SW and designated by the MPC (see item 6, CCNet 26
September)....and it is an Aten (mag. 29.1)! The
orbit and details are now on file.
The closest approach of this little jewel was on the
19th of September (about 162,000 km away and less than
half the distance to the moon). It was tricky, but
they found it...using the 1.8 meter that Tom and his
team worked so hard to build. We salute the entire SW
team for this accomplishment and for their long and
dedicated support of planetary protection. They
pioneered CCD asteroid hunting...and they have paved
the way for the rapid growth of our critical
data-base....and LINEAR and NEAT and LONEOS and others
have joined, in a great way, in this important
mission.
Orissa Connection
As they were observing this new object, for 3 nights,
they noticed that the trail had decreased to about 1/4
its original size. We noticed 130, at the head of the
MPC Aten list, as we were searching for possible
companions of or parents to Orissa (and possibly
others).
We again ask the "big boys and girls", in the NEO
hunting community (and others with large telescopes)
to keep an eye out for other "little ones", over the
next week or two. Also, it would be nice to know if
the dots can possibly be connected...between 130 and
Orissa.
Cheers,
Andy Smith/IPPA
astrosafe22000@yahoo.com
============
(9) NO CONNECTION BETWEEN ASTEROIDS AND METEORITES
Brian Marsden <brian@cfaps5.cfa.harvard.edu>
Dear Benny,
While I appreciate Andy Smith's
kind comments about the cooperation that
allowed a rather good orbit determination to be made for 2003
SW130, I don't
think for a moment that there was any connection with the Orissa
meteorite,
which, after all, fell a good week after the asteroid's
pass. Coming to
within some 160,000 km of the earth, SW130 made the sixth closest
approach
known for an asteroid. Actually, it was then the fifth
closest approach,
for we now have 2003 SQ222, which came to a record close distance
of 90,000 km
--just a few hours after the meteorite. But again, I
strongly doubt any
connection, and SW130 and SQ222, though both probably smaller
than 10 meters
across, themselves have very different orbits. And not
entirely by chance,
SQ222 also represented an excellent case of cooperation, for
Peter Birtwhistle
succeeded in securing images of it from his observatory in Great
Shefford,
Berkshire, between the sets made by the LONEOS survey in Arizona
on Sept. 28
and 29.
While the information about the
trajectories of the recent meteorites and
fireballs is more spotty than that about the two asteroids, there
is again no
reason to relate them. On Monday, the same day I read in
CCNet about the
Orissa meteorite, I had a visit from a high-school student who
had done some
research on 1999 AN10 a couple of years ago and was here to
participate in the
early-applicant process for Harvard University, which he would
like to attend
a year from now. He was not himself aware of the Orissa
meteorite at the time,
but in the course of our discussion he happened to mention that
his mother
came from Cuttack, one of the towns in Orissa from which I had
read of
sightings of the meteorite. Cuttack, Orissa, is not a
geographical location
that generally comes to my mind even once a day.
Regards
Brian
=======
(10) TIME OF 'FIREBALL' EVENT OVER SOUTH WALES
Jon Burnett< Burnskatejon@aol.com>
Hi
This is Jon Burnett. I took the photo last wednesday, the 24th
03, around 6 to half past
in the evening.
Jon Burnett
============
(11) PEGASUS A FALL REFERENCE POINT TO LOCATE AND VIEW COMET
ENCKE
John Michael <john.michael@morien-institute.org>
Dear Benny,
It seems that later this month on October 25th the Earth will be
in just the right place, and with a much desired moonless night,
for skywatchers with a good pair of binoculars or a small
telescope to see Comet Encke as it passes by the M31 Andromeda
Galaxy. More details from:
The Oregonian - October 1st 2003
http://www.oregonlive.com/science/oregonian/index.ssf?/base/science/1065009370244190.xml
"Pegasus a fall reference point to locate, view Comet
Encke"
When it comes to finding interesting objects in the sky, one
thing often leads to another.
This month, the most prominent constellation of the fall will
lead skywatchers to views beyond our Milky Way galaxy and later
in the month right to a passing comet.
Look to the southeast as darkness falls and you will see four
bright stars forming a large square. This is the Square of
Pegasus, the easy-to-spot feature or "asterism" of the
constellation Pegasus. When you look in this direction, you are
looking perpendicular to the spiral arms of the Milky Way galaxy
that covers the sky in summer. The Square of Pegasus serves as a
window into deep space.
From a city location, this window seems empty, framed only by the
bright four, relatively nearby stars. A clear night from a dark
location will reveal more -- dimmer and more distant stars inside
the window. Grab your binoculars and you will see many more stars
that lie even deeper in space. A small telescope will reveal
stars at the very edge of our galaxy, and if you know where to
look, you can spot distant galaxies that are island universes of
stars millions of light-years away.
Observing distant galaxies is challenging for telescope owners
under very dark skies, but one galaxy can be found easily without
optical aid from a dark location and with binoculars from
anywhere. The Andromeda galaxy, also known as M-31, is a giant
companion to the Milky Way galaxy. At more than 2 million
light-years distance, it is the farthest object visible with the
unaided eye. It lies very near Pegasus.
First find the not-very-conspicuous stars of Andromeda, connected
to the Great Square. Look for a long lazy "V" of stars
extending to the left from the northeast corner of the square.
North of the V is M-31, which appears as an elongated hazy patch
of light. It covers more sky than the full moon and won't fit in
the field of view of most telescopes. Binoculars offer the best
view. Although comprised of billions of suns, the galaxy is so
distant no telescope on Earth can reveal individual stars without
taking a long exposure photograph.
If you can find M-31, you can find Comet Encke just as it first
comes into view. Comet Encke was the second comet, after Halley,
to have its orbit around the sun defined. Although Encke appears
every 3.3 years, the Earth has to be in just the right place, as
it is this year, for us to have a good view. A moonless night is
a must for viewing this comet, and just such a night occurs Oct.
25 when Encke moves past what should now be the familiar
Andromeda galaxy.
The comet becomes bright enough to be seen in good binoculars or
a small telescope at this time. Look two finger-widths above the
galaxy. It will appear as a hazy patch with a bright center. Once
you have found Comet Encke, keep track of it as it crosses the
sky and grows to maximum, naked-eye brightness toward the end of
November.
Planets shine Mars continues to attract attention during October.
Although slowly fading, the Red Planet still appears larger in
telescopes than it will be until 2018, and it will remain in the
night sky not only throughout fall, but for months to come.
Jupiter shines brilliantly above the eastern horizon before
sunrise, and fleet Mercury joins it at the beginning of the
month. The tiny planet disappears in morning twilight by the end
of the first week of the month.
Regards to all on the CCNet,
John Michael
-----------
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*
CCNet 82/2003 - 2 October 2003
------------------------------
Small meteorites are not hot when they hit the ground
(they are only heated briefly as they pass through the
atmosphere, and generally have some minutes to cool when
they reach terminal velocity after the huge deceleration
phase of their fall). The Orissa event caused fires, so
I am very curious about whether there are indeed some cases
of small meteorites hitting while still hot, or if this
is perhaps not a true meteorite.
--Phil Plait, 2 October 2003
(1) CLOSEST ASTEROID YET FLIES PAST EARTH
(2) ORISSA EVENT RAISES QUESTIONS
(3) DID COMETS MAKE LIFE ON EARTH POSSIBLE?
==========
(1) CLOSEST ASTEROID YET FLIES PAST EARTH
New Scientist, 2 October 2003
http://www.newscientist.com/news/news.jsp?id=ns99994228
An asteroid about the size of a small house passed just 88,000
kilometres from the Earth by on Saturday 27 September - the
closest approach of a natural object ever recorded. Geostationary
communication satellites circle the Earth 42,000km from the
planet's
centre.
The asteroid, designated 2003 SQ222, came from inside the Earth's
orbit and so was only spotted after it had whizzed by. The first
sighting was on Sunday 28 by the Lowell Observatory Near-Earth
Object Search program in Arizona, US.
Amateur astronomer Peter Birtwhistle of Great Shefford,
Berkshire,
UK, then photographed it on Monday 29. This provided data that
helped Brian Marsden, of the Harvard-Smithsonian Center for
Astrophysics, to calculate its orbit.
The asteroid's 1.85-year orbit is quite eccentric, indicating it
cannot be a man-made object, Marsden says. He estimates the
asteroid measured less than 10 metres. This is too small to have
posed a danger to Earth, although it would have made a
spectacular
fireball had it entered the atmosphere.
House fires
The passage came at about 2300 GMT, only 10 hours after a bright
fireball streaked over the Orissa region of India. Indian
villagers
have found pieces of the meteorite, which reportedly cause two
house
fires. However, this event was not connected to the fly past of
2003
SQ222, says Marsden.
The previous record for closest approach of an asteroid -
108,000km
measured from the centre of the Earth - was set in 1994 by
another
10m object named 1994 XM1.
But the third-closest approach - at 120,000km - was object 2002
MN,
which was about 80m in diameter. If on target, that could have
exploded in the Earth's lower atmosphere and devastated a couple
of thousand square kilometres on the ground.
Another small asteroid, 2003 SW130, missed the Earth by 160,000km
on
19 September, making it a busy month for asteroid watchers.
Jeff Hecht
Copyright 2003, New Scientist
=============
(2) ORISSA EVENT RAISES QUESTIONS
Phil Plait <badastro@badastronomy.com>
Hi Benny!
I am following the news from Orissa with keen interest, as I
imagine
many of your readers are. I'm suspicious though; as I've written
before, small meteorites are not hot when they hit the ground
(they
are only heated briefly as they pass through the atmosphere, and
generally have some minutes to cool when they reach terminal
velocity
after the huge deceleration phase of their fall). The Orissa
event
caused fires, so I am very curious about whether there are indeed
some cases of small meteorites hitting while still hot, or if
this
is perhaps not a true meteorite. For example, space debris (spent
rocket
engines, for example) can still be hot upon impact. We have seen
many
claims of meteorite impacts that have turned out to be other,
more
mundane objects such as fireworks. While the Orissa object was
clearly not fireworks, I am not yet convinced we know it was a
meteorite.
Please keep us up-to-date with the latest findings! I will be
very
interested in reading about what the experts determine about this
event.
-Phil
* * *
* * The Bad
Astronomer *
* * *
Phil
Plait
badastro@badastronomy.com
The Bad Astronomy Web Page: http://www.badastronomy.com
============
(3) DID COMETS MAKE LIFE ON EARTH POSSIBLE?
National Geographic News, 2 October 2003
http://news.nationalgeographic.com/news/2003/10/1002_031002_cometstudy.html
Stefan Lovgren
An ambitious new NASA research project aims to answer perhaps the
most vexing and profound of scientific mysteries: How did life on
Earth begin?
The multimillion-dollar undertaking, led by the NASA Goddard
Space Flight Center in Greenbelt, Maryland, brings together an
interdisciplinary team of scientists from around the world to
study how organic molecules are created in interstellar clouds
and delivered to planets as they form.
The research will focus on the role of comets. Many scientists
believe there is increasing evidence that comets supplied at
least part of the raw material for the origin of life on Earth.
The theory is changing the way scientists think about life in the
universe and raises the possibility of alien worlds.
"Our mission is to gain a greater understanding of the
origin and evolution of organic material on Earth," said
Michael Mumma, a comet expert and director of the Goddard Center
for Astrobiology, NASA Astrobiology Institute, who is leading the
research. "The key question is: Were water and organic
molecules delivered to Earth by cometary impact and does [that
process] extend to planets elsewhere?"
Dirty Snowballs
Astronomers believe that stars, planets, and comets form in a
massive chain reaction that begins when a cloud of interstellar
material collapses under its own gravity. Some of the material
forms the star-like our sun-and some of it gets spread out in a
disk around the nascent star.
Some material in this disk later aggregates and forms planets.
Close to the sun, where it's warm, leftover debris (rocky
material) turns into asteroids. In the outer regions, where it's
cold, icy chunks of rock and dust turn into comets.
It is generally believed that organic molecules, which contain
carbon atoms and are present in all life forms known to science,
are trapped in large amounts in both interstellar clouds and
comets.
"We have extremely definite evidence from our radio
observations that there's quite an array of organic molecules in
interstellar space," said Bill Irvine, a professor of
astronomy at the University of Massachusetts in Amherst, who is
measuring radio waves from celestial objects as part of the
research effort.
There's other evidence that comets contain organic material. When
European spacecraft analyzed dust particles from the Halley comet
in 1986, it turned out to be some of the most organic-rich
material measured in the solar system. Meteorites that have hit
Earth contain a whole suite of molecules, including amino acids,
which play an important role in terrestrial biology.
"If such material exists in meteorites, which come from a
class of asteroids, there's every reason to think it must also
exist in comets," Irvine said.
Panspermia Goes Primordial
Most scientists have long believed that life on Earth began as a
"primordial soup" in a lake or pond some four billion
years ago. According to this theory, chemicals from the
atmosphere combined with some form of energy necessary to make
amino acids-the building blocks of proteins-to create the first
primitive organisms, kicking off the evolution of Earth's
species.
But the primordial soup theory is being increasingly disputed.
Many geophysicists now say the Earth did not have enough gases,
like ammonia and methane, from which organic material like amino
acids could be produced.
Instead, a growing cadre of scientists believes the organic
material needed to create life may not have been produced on
Earth, but was instead brought here by comets. The newly formed
Earth was likely subjected to a fierce bombardment of comets four
billion years ago. These comets may have brought with them the
organic compounds that later evolved into living matter.
According to the most radical theory, known as
"panspermia," life in a ready-made form is ubiquitous
in the galaxy and is brought by comets to new planets. Few
scientists subscribe to this hypothesis, however.
Perhaps the main question is whether organic molecules can
survive space travel or if they break up and contribute the atoms
that are necessary to ultimately make biological material and
water?
"Our museums contain examples of primitive meteorites that
likely are very similar to the material delivered by
comets," said Mumma. "The key point is that small
bodies deliver their organics intact to Earth's surface. This
must have been a common event on the early Earth."
Many scientists are now leaning toward a combination of the comet
impact theory and the primordial soup thesis. Some chemical
building blocks may have come from comets, but the assembly into
life took place on Earth.
"The comet impact theory fits in with the primordial soup
theory," Mumma said. "They can be complimentary."
Drilling Into Comets
Scientists will measure the molecular make-up of comets to better
understand what chemical reactions formed them. This may provide
clues to the evolution of carbon-based chemistry on Earth in its
early history.
The new research will combine laboratory experiments,
observations with telescopes and spacecraft, and missions to
sample comet and asteroid material. A European mission not
associated with NASA is even going to land on a comet and drill
into it as the comet journeys toward the sun.
An important part of the project will focus on water, which is
seen as an essential ingredient of life. Scientists want to know
if the Earth's water was incorporated into the Earth as the
planet formed or if the water arrived on Earth as a result of
cometary impacts after the Earth was already formed.
"Earth's new oceans were filthy, and should have been full
of organic molecules and dust particles carried to our planet by
comets and primitive meteorites," said Mumma. "We want
to learn how significant their contribution was to the genesis of
life on Earth."
The comet research could have a tremendous impact on the quest to
find life on other planets. After all, comets have slammed into
many other planets. If they supplied the raw material to form
life on Earth, what is to say the same thing hasn't happened on
other planets?
One thing is for sure, however. Finding out exactly how life on
Earth began, and if it extends elsewhere, will take some time.
The first stage of the NASA project will last five years, but
Mumma thinks it could take as much as 25 years before scientists
have a definite answer about the origin of life on Earth.
Copyright 2003, National Geographic News
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