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(meteorobs) RE: meteorobs-digest V1 #457
Please delete my name from this distribution list.
Thank-you
----------
From: owner-meteorobs-digest@latrade.com
Sent: Thursday, May 29, 1997 6:00 AM
To: meteorobs-digest@latrade.com
Subject: meteorobs-digest V1 #457
meteorobs-digest Thursday, 29 May 1997 Volume 01 : Number
457
----------------------------------------------------------------------
From: donwon1@juno.com (Conrad W Humphrey)
Date: Sun, 25 May 1997 16:25:45 EDT
Subject: (meteorobs) Meteorite value...
Hi again,
I would like to know how much a planeterium would pay for a
meteorite. It`s not like I have one but I just wanted to know. Also, I
read in a book that during a major meteor shower you should put a pan on
your roof wrapped with aluminum foil. Then pick it up after it rains
because of the dust from the meteors can land in the pan. Then with a
magnet sweep the bottom of the pan with the magnet so you can pick up the
dust particles from the meteors since some meteors are made of iron. Then
dry the pan over a fire and look for the stony pieces. When you`re done
the book say`s rub a nail with the magnet and pick up the iron pieces and
then you can a sample of a meteorite. Is this true?
Conrad (Amatuer Astronomer)
Donwon1@juno.com
41 N
69 E
P.S.. Have any of you found a meteorite and did you sell it or keep it.
------------------------------
From: NTZT04A@prodigy.com ( THOMAS T WOJACK)
Date: Wed, 28 May 1997 10:53:36, -0500
Subject: (meteorobs) Meteorite value...
>...I would like to know how much a planeterium would pay for a
meteorite. It`s not like I have one but I just wanted to know....>
You don't have what? A planetarium or a meteorite?
Jonathan
------------------------------
From: tpcooper@ilink.nis.za
Date: Wed, 28 May 1997 17:50:45 +0200 (SAT)
Subject: (meteorobs) Sagittarids
Some feedback from meteorobs digest no.456 (the first I've received in
over
a week - is everyone hibernating up there?).
Mark wrote:
>The majority of these will be the various ecliptic showers
>radiating from the Scorpius - Sagittarius region. The IMO has combined
all
>of these minor radiants into one broad shower...the Sagittarids. NAMN
>members are encouraged to follow suit.
Hi Mark, I'll be out continuing my plotting program started a few years
ago
on the Scorpio/Sagittarids. Last year I found around 5 active radiants.
I'll do the same this year and report each active radiant rather than
lump
them all as Sagittarids. the radiants are up all night here and pass
overhead around local midnight. I suppose that is different to your
situation. I'd be happy to confirm any activity you guys observe from up
north. That's if the weather clears in time. We have had rain since the
weekend, and today it snowed briefly here in Johannesburg (hey Cathy, the
Great White South??)
KevTK@aol.com wrote:
><<Has anyone recieved the July issue of _ASTRONOMY_?
>It has a new design that I think is a lot better!>>
>
>
>Someone please tell me what any of this has to do w/ Observing Meteors?
Beats me. Come on guys, PLEEEEEZE can we limit the non-meteor waffle on
meteorobs.
Bye
Tim
------------------------------
From: rhawkes@mtadot ca (Robert Hawkes)
Date: Wed, 28 May 1997 13:11:13 -0300
Subject: (meteorobs) Activity May 27/28, 1997?? and Interstellar
Meteorites??
This note contains two UNRELATED points.....
(a) Last night (May 27/28) we (myself and 4 undergraduate honours
student
researchers working in our lab) were testing out some equipment
modifications to our image intensified detection systems + a prototype
wide
field fireball detection system, when we noticed an apparent high rate of
meteor activity on our image intensified video detection equipment. With
a
system which usually detects about 8-20 sporadic meteors per hour we were
detecting apparent shower activity at a rate of about a meteor per
minute.
After some scrambling we got a recording system going while the activity
was still moderately high. We have not yet had time to digitize and
analyze these "meteors" - I use the quotation because although they
certainly appeared to be meteors (we routinely get bugs, birds, bats,
planes and satellites - all of which are usually easily distinguished by
nonlinear or nonuniform velocity trails) we have not yet absolutely ruled
out migratory, high flying birds in very straight, very regular flight.
We've not yet computed a radiant, but it was low in the south to sout
south
west sky during 10:30 to 12:30 pm local daylight time. The rate had
dropped sharply by 12:30 ADT (03:30 UT) and we packed up about 04:00 UT.
The rate seemed highest from about 01:15 to 02:15 UT. Although a few
visible meteors were seen, this shower (if they do turn out to be
meteors)
seemed largely restricted to the magnitude range from +3 to +8 magnitude.
DON'T REGARD ANYTHING IN THIS NOTE AS DEFINITIVE - WE MAY DECIDE THEY ARE
NOT SHOWER METEORS WHEN WE GET THE DIGITIZATION AND ANALYSIS DONE. I DID
WANT TO ALERT PEOPLE IN CASE OTHERS HAVE OBSERVED UNUSUAL RATES OF FAINT
METOERS OR WANT TO SEARCH TONIGHT IN CASE THERE IS A REPEAT.
(b) Thanks to Cathy Hall for recently posting a good summary of our
"interstellar meteorite?" paper from JRASC. If anyone has questions or
comments, don't hesitate to ask/tell (rhawkes@mtadot ca). Also, I would add
that we now have two definitive optically detected interstellar origin
meteors (note I say meteors - these were around mass of 10^-8 kg -
certainly not meteorite producing). We have a detailed paper on this
which
has been submitted to Monthly Notices and is currently being refereed
(also
a short announcement submitted to JRASC). I will post to this list a
brief
rundown once we have heard from the referees. It is our opinion that the
fraction of interstellar origin meteors goes up sharply with decreasing
mass. We are currently hoping to extend our detection capability
somewhat,
and working on models for production of such meteors.
Bob Hawkes
Mt. Allison Meteor Group
Mount Allison University
Sackville, NB, Canada
MAMG
------------------------------
From: GeoZay@aol.com
Date: Sun, 25 May 1997 14:07:49 -0400 (EDT)
Subject: (meteorobs) Florida Fireball May 24
this was posted on the astronomy mailing list this morning...anybody in
florida have any reportings? Sounds like it could be a re-entering
satellite
of some kind to me?
George Zay
- ---------------
<< From: steves@flinet.com (steve sanacore)
Hi all;
I just observed a large biggest fireball that must have gone at least 90
degrees across the zenith from North to South at aprox. 11:40pm Sat. May
24, 1997. I am in South Florida. Did anyone else see this? A few
questions came to mind after witnessing such a bright show. It was
clearly a red fireball with a trail of sparks and smoke that lasted a
few seconds. The sky was fairly light with the moon rising in the East.
Just how large would such a meteor have to be to create such a sight? It
did clearly go dark well above the horizon, so does that mean that it
probably disintegrated well before reaching the surface? ...Steve<<
------------------------------
From: Lew Gramer <dedalus>
Date: Wed, 28 May 97 12:52:02 -0400
Subject: (meteorobs) List problems!
Sorry to all subscribers for any inconvenience: below is a message from
the
systems administrator at "latrade.com", explaining. Welcome back all! :)
Lew
- ------- Forwarded Message
From: Cliff Krieger <ckrieger>
Subject: mail
To: everyone
Date: Wed, 28 May 1997 09:20:53 -0400 (EDT)
If you haven't noticed by now, mail has not been getting in for several
days. It seems that the mail daemon on gatekeeper died. It looks like
it happened on Friday some time just after I left. I swear, you take
one little extra day off, and it all goes to hell in a hand basket!
Anyway, mail should start flooding in over the next 6 or so hours. If
you are a member of a particluarly picky mailing list, you may have to
resubscribe.
- -cliff
- ------- End of Forwarded Message
------------------------------
From: tmcewan@kersland.u-net.com (Tom McEwan) (by way of Lew Gramer
<tmcewan@kersland.u-net.com>)
Date: Wed, 28 May 1997 14:41:28 -0400
Subject: ARCHIVE RESEND: (meteorobs) Noctilucent Clouds
Hello everyone!
Please remember that the Noctilucent Cloud (NLC) season is now
underway. As in 1996, my web site will be accepting and posting NLC
reports via the Internet. I'd be glad to hear from anyone who feels
able to contribute to this.
Further information is available from the URL in my sig.
Tom
- ------------------------------------------------------------------
Tom McEwan tmcewan@kersland.u-net.com
NLC Info: http://www.personal.u-net.com/~kersland/nlc/nlchome.htm
- ------------------------------------------------------------------
------------------------------
From: RMetz11126@aol.com
Date: Wed, 28 May 1997 18:00:13 -0400 (EDT)
Subject: (meteorobs) I new to this.
Hello everyone,
I just recently got into this meteor thing. While I've been watching the
skies for years, I never really took an interest in astronomy, except in
passing. You know, the occasional NOVA episode or a program on The
Discovery
Channel or The Learning Channel. I'm so out of it that I couldn't even
spot
a constellation if I tried, except for Ursa Major, Ursa Minor, and Orion,
but
they're pretty obvious. The thing is, back on the night of March
12/13th, I
spotted a large fireball, which exploded over Ontario. I wanted to
report it
and did, but in the process I discovered how little I knew. It was hard
for
me to describe, except in very loose terms what I saw. I couldn't give a
magnitude; I couldn't describe ,with any accuracy, what part of the sky
my
sight of the object originated from; the duration of the sighting; the
length
of the trail; or the part of the sky where the fireball exploded. I
wanted
to report it, but my lack of knowledge made my report, nearly worthless.
In the process of trying to find a place on the web to report the
fireball, I
discovered this maillist and subscribed to it, hoping that I could learn
from
it and be better prepared in the future. Now, I find that my vacation is
fast approaching. A time when I will be able to get out of the city and
be
in the country where light pollution will not be a detriment to my sky
gazing. My vacation begins on June 4th and lasts for one week. From
reading
the list, I find that there is going to be this shower going on during
that
time: the Saggitarids. Can anyone give me pointers, because, weather
permitting, I'm going to be out there looking every night.
Bob
Metzger
P.S. I live in Western New York.
------------------------------
From: wayne.t.hally@bangate1.TEK.COM
Date: Wed, 28 May 97 12:23:42 EDT
Subject: re: (meteorobs) I new to this.
Welcome, Bob
Since you're leaving so soon, let me throw out my 2 cents. The
Sagittarids appear to radiate from the constellation Sagittarius, the
archer. Since you don't know how to find it, I'll try and describe what
to
look for. You will find it low on the eastern Horizon after midnight. The
brightest object by far over there is Jupiter, which rises after SAG (I'm
going to abbreviate Sagittarius as SAG, since it's too much to type.)
If you can see it, then SAG is above and to the right. It's often
described
as a teapot, I'll try and draw a picture below. Further to the right and
above is Scorpio, which has a bright red star. (Jupiter is much brighter,
and white). The SAG meteors come from a wide area, so if you can trace
the
meteors path backwards, past where it started to glow, and that path
crosses the general area, it may well be one. These are medium slow
meteors,
but of course, until you've seen a lot of meteors, fast and slow, that
doesn't mean much.
At best, unfortunatly you might see 3 or 4 SAG's an hour, since this is
a
weak shower. The Perseids in August are much more fun to watch, but if
you
can get out there to look, why not watch for a while. Tell us what you
see,
and we'll help you learn! I assume you're from Ontario, since that's
where
you saw the meteor (PS did you hear a Boom several minutes later ?),
perhaps our protector of the Great White North, Cathy, can get you to
join
a meteor watch later in the summer.
If you want to learn about meteors just by lurking here that would be
fine....if you'd like more information, such as the NAMN Guide, just let
us
know, and Mark will be happy to send it to you.
Feel free to ask any meteor questions here, and you can e-mail me
directly
as well if you wish.
Good luck! and here's my ascii map of Sagittarius: Can you see a
teapot???
:->
*
* *
* *
*
* *
Wayne
------------------------------
From: Lew Gramer <lewkaren@tiacdot net>
Date: Wed, 28 May 1997 18:51:23 -0400
Subject: Re: (meteorobs) no messages ? and perception.
At 11:01 AM 5/28/97 +1000, you wrote:
>One question to you all though, observers perception, I don't have alot
>of info on it and I was wondering the best way to work it out for
>observers in our group.
>Adam Marsh, ASV
Hey, Adam, thanks for the message. This sounded like a real good
question,
but I was wondering what specifically you were referring to? Are you
talking about the "perception coefficient" that can be applied when
analyzing meteor data, or something else? Please write back, as I was
intrigued!
Clear skies,
Lew
------------------------------
From: wayne.t.hally@bangate1.TEK.COM
Date: Wed, 28 May 97 12:59:13 EDT
Subject: re: (meteorobs) I new to this.
HHmmmmm
I didn't like my drawing at all, it came out way too flat, so I'll try
again
*
* *
* *
*
* *
So try this, or get a constellation book or planishere to see what it
really looks like :-)
I tried
Wayne
------------------------------
From: richardson@digitalexp.com (Richardson, James)
Date: Wed, 28 May 1997 18:35:49
Subject: (meteorobs) Forwarded News: Arecibo and Micrometeors
Forwarded news release:
Date: Wed, 28 May 1997 18:27:13 GMT
From: Ron Baalke <BAALKE@kelvin.jpl.nasadot gov>
To: meteorite-list@meteoritecentral.com
Subject: Elusive Micrometeorites May Come From Dawn of Solar System
The Pennsylvania State University
Contact:
A'ndrea Elyse Messer (814) 865-9481 (office) (814) 867-1774 (home)
aem1@psudot edu
Vicki Fong 814-865-9481 (o) 814-238-1221 (h) vyf1@psudot edu
5-27-97
Elusive Micrometeorites May Come From Dawn of Solar System
Baltimore, Md. -- Millions of incredibly old, minute, previously
undetected invaders enter the Earth's atmosphere every day and
until recently, no one has been able to track, count or
investigate them, according to a Penn State researcher.
These micrometeorites are so small that even when they
disintegrate in the atmosphere, they are presently only recordable
at high-resolution using the very sensitive 430 megahertz radar
system at Arecibo Observatory in Puerto Rico.
"Radio and radar telescopes have always seen meteors and generally
considered them noise," says Dr. John D. Mathews, professor of
electrical engineering and director of Penn State's Communications
and Space Sciences Laboratory. "It has only been with recent
technology that we can observe these micrometeorites at extremely
high velocity resolution."
Another reason to look at meteors is the expected peak in November
1999 of the Leonid Meteor Shower. Both the U.S. Air Force and NASA
are concerned with an increase in potential damage to their
satellites and spacecraft. Historical pictures of the Leonids
shows a sky painted with multiple meteor trails, indicating that
the visible meteors were numerous.
While Mathews and his collaborators observed the Leonid Shower
from Arecibo in 1995 and 1996 and plan to observe the Leonids
every year until 2001, observations suggest that these
micrometeorites are not associated with the cometary debris
streams that cause meteor showers, but are entering the earth's
atmosphere all the time and from all directions accessible from
Arecibo.
"We can track the micrometeorites' orbits back through time, and
most of these tiny rocks appear to originate on the edges of our
solar system and not in the trails left by comets," Mathews told
attendees today (May 27) at the spring meeting of the American
Geophysical Union in Baltimore. "We think that the material in
much of the micrometeorites that we see is left over from the
formation of the solar system.
"We do have one candidate that might prove to come from outside
the solar system," Mathews added. "It moved too fast not to be
interstellar in origin."
The researchers have not accurately traced its possible stellar
origins yet because that requires a complex back tracking of both
the micrometeorites and the solar system as it moves through
space.
While micrometeorites disintegrate at about 60 miles above the
earth and weigh only about one microgram, they carry the energy of
a 22-caliber bullet.
"Spacecraft always become pitted, and it is attributed to dust or
space junk, these micrometeorites are probably the dust that pits
the surface of satellites," says Mathews. "They are also fairly
abundant. An object the size of the new Space Station would be
struck by one of these micrometeorites about once every orbit."
At Arecibo, one micrometeorites crosses through the 990-diameter
radar beam every minute. These events are not rare, just small and
illusive.
Mathews and his collaborators, Professor D.D. Meisel, Department
of Physics and Astronomy, State University of New York Geneseo,
and Qihou Zhou, staff scientist, Arecibo Observatory and a 1991
Penn State doctoral recipient, are also interested in these
micrometeorites because of the way they interact with the upper
atmosphere and the way they appear on radar.
"Regardless of the radar wavelength we use, we get the same
signature," says Mathews. "This appears to mean that we see a
shell of free electrons just surrounding the meteor, not the
meteorite itself."
The researchers don't know how the micrometeorites generate these
electrons. The particles are so small that when they enter the
upper atmosphere, they travel between air molecules.
"The interaction between the particles and the air before the
particles burn up or disintegrate is very interesting and not
understood," says Mathews. "Air molecules numbering only one
percent of the molecules in the particles are apparently
sufficient to destroy the micrometeorites."
**aem**
EDITORS: Dr. Mathews may be reached at (814) 865-2354 or
JDMathews@psudot edu
End of forwarded message.
James Richardson
Graceville, Florida
richardson@digitalexp.com
Operations Manager / Radiometeor Project Coordinator
American Meteor Society (AMS)
http://www.serve.com/meteors
------------------------------
From: Jim Bedient <wh6ef@pixi.com>
Date: Wed, 28 May 1997 14:15:27 -1000
Subject: (meteorobs) Hawaii Jobs
Several people wanted to know more about the following, so what follows
are
EXCERPTS and contact points for these positions:
FACILITIES TECHNICIAN
National Astronomical Observatory of Japan. Responsible for maintenance
of
facilities on the summit of Mauna Kea and support facilities in Hilo.
Requires: H.S. Diploma, formal tech. training, 5 years exp. in a large
facility. Journeyman-level skills in electrical work, knowledge of
computers, plumbing, HVAC, waste management & safety. Ability to operate
a
crane & crane carrying truck. Min salary $2592/mo.
Send resume with ID# (this is #171) salary history, names and phones of 3
work references, and copies of certificates to:
Dir. of Human Resources
Research Corporation of the University of Hawaii
2530 Dole St., Sakamaki Hall D-100
Honolulu, HI 96822
Inquiries: Tetsuo Nishimura, 808-934-5085 Closes 6/2/97.
-
--------------------------------------------------------------------------
----
ELECTRONICS TECHNICIAN
The Canada-France-Hawaii Telescope Corporation which operates a 3.6 meter
astronomical telescope on Mauna Kea, has an opening for an electronics
technician experienced in the operation, maintenance and design of
electronic and electro-mechanical systems. Duties include: design,
construction, installation, testing, calibration, troubleshooting and
maintenance, and user support of electro-mechanical systems. The same
for
the networked PC system controlling all this. Requires: BSEE, four years
experience, proficient with test equipment, experience providing system
manager and repair services to networked PCs. Desirable: knowledge of
closed-loop servo control and programming for control of
electro-mechanical
devices; CAD; astronomical instrumentation.
Salary commensurate with qualifications.
Inquiries, or detailed resume to:
CFHT Corp.,
Attn. Electronics Tecnician
P.O. Box 1597
Kamuela, HI 96743
Closes: 2 June.
-
--------------------------------------------------------------------------
----
One more that I overlooked:
UH HALEAKALA HIGH ALTITUDE SITE SUPERINTENDANT
Located at Kula, Maui. Responsible for the overall management of
activities
within the Institute for Astronomy's Haleakala High Altitude Site,
support
facilities in Kula, the Kihei High Tech Park on the island of Maui, and
reserach facilities at the Haleakala Observatory...
Requires: 4 year degree in engineering and 8 years of progressively
responsible experience in managing a technical observatory installation,
or
equivalent.
Pay Range: P15, $4682/mo.
Inquiries and application form: Michele Tom, 808-956-7593. Closes 6/24
-
--------------------------------------------------------------------------
----
NOTE: I take no responsibility for ANY of the above. I'm just relaying
a
little of what I saw in the Sunday paper in response to some requests.
Though I am a part-time employee of RCUH, I have no inside knowledge of
the
RCUH position above, and I wouldn't even know who to ask.
Aloha,
Jim Bedient
American Meteor Society
Honolulu, Hawaii
------------------------------
From: Mark Davis <MeteorObs@Charlestondot net>
Date: Wed, 28 May 1997 20:35:58 -0400
Subject: (meteorobs) Bolide Sighted From California on May 26
Passing on the following from the meteorite list just in case....
- -Mark
>There has been a couple of reports of a bright bolide sighted from
>Santa Barbara and Los Angeles on the evening of May 26. If anyone
>may have witnessed this bolide, please contact me.
>
>Ron Baalke
>baalke@kelvin.jpl.nasadot gov
>
>
------------------------------
From: Adam Marsh <riker@alphalink.com.au>
Date: Thu, 29 May 1997 10:54:20 +1000
Subject: (meteorobs) Observer perception (Lew)
Hi Lew, Hi all
Its a little bit of a story.
In our group, we've noticed that between our different observers, after
we averaged our hourly rates out for each observer that two of our group
had very low rates overall (when observing on the same night and
location as the others) and that one of our members had higher rates
than the rest. I belive i've read somewhere that every person has a
different sensitivity to a quick flash of light such as in the case of a
meteor. So when observing if a person has a lower 'perception' they
will see less meteors. I was wonndering if there is any way to
calculate this for each observer in a group ?
I've herd a little about 'perception coefficient' could somebody explain
how this is worked out and applied
Thanks and Clear skies
Adam
------------------------------
From: Cathy Hall <72732.3246@CompuServe.COM>
Date: 29 May 97 01:38:51 EDT
Subject: (meteorobs) Test message...
Hi guys -
Just a test message. Got home about half an hour ago, and had 100
messages in
my in basket. Our RASC list has had a major bounce problem tonight, and
as a
result (and my in basket limit), I think I <might> have caused some
meteor mail
bouncing....
Apologies if this has happened.... I have unsubscribed from our RASC
list with
hopes they'll get it fixed soon..
- - Cathy Hall(y)... ;)
------------------------------
From: Sirko Molau <Sirko.Molau@dlrdot de>
Date: Thu, 29 May 1997 11:57:40 +0200 (MET DST)
Subject: (meteorobs) Polar Spacecraft Images Support Theory of
Interplanetary Snowballs (fwd)
From owner-press-release-other4@lists.hq.nasadot gov Wed May 28 17:03:34
1997
Date: Wed, 28 May 1997 10:43:20 -0400 (EDT)
From: NASANews@hq.nasadot gov
Subject: Polar Spacecraft Images Support Theory of Interplanetary
Snowballs
Spraying Earth's Upper Atmosphere
To: undisclosed-recipients:;@lists.hq.nasadot gov
Douglas Isbell
Headquarters, Washington, DC May 28, 1997
(Phone: 202/358-1753)
William A. Steigerwald
Goddard Space Flight Center, Greenbelt, MD
(Phone: 301/286-8955)
RELEASE: 97-112
POLAR SPACECRAFT IMAGES SUPPORT THEORY OF INTERPLANETARY
SNOWBALLS SPRAYING EARTH'S UPPER ATMOSPHERE
Images from NASA's Polar spacecraft provide new evidence
that Earth's upper atmosphere is being sprayed by a steady
stream of water-bearing objects comparable to small comets.
Using Polar's Visible Imaging System (VIS), a research
team led by Dr. Louis A. Frank of the University of Iowa in
Iowa City has detected objects that streak toward Earth,
disintegrate at high altitudes and deposit large clouds of
water vapor in the upper atmosphere. Frank's research is being
reported in a news briefing at 10 a.m. today at the spring
meeting of the American Geophysical Union at the Convention
Center in Baltimore, MD.
The incoming objects, which Frank estimates to be the size
of a small house, pose no threat to people on Earth, nor to
astronauts in orbit. "They break up and are destroyed at 600 to
15,000 miles above the Earth," Frank noted. "In fact, this
relatively gentle 'cosmic rain' -- which possibly contains
simple organic compounds -- may well have nurtured the
development of life on our planet."
"This is an intriguing result that requires further scientific
investigation," said Dr. George Withbroe, science director for the
Sun-Earth
Connection program in NASA's Office of Space Science. "We need
to look closely at measurements from other sensors to find out
if they see related signatures in the atmosphere, now that we
have learned more about what to look for."
The Polar cameras have imaged trails of light in both
ultraviolet and visible wavelengths as the objects disintegrate
above the atmosphere. Using a filter that detects visible
light emitted only by fragments of water molecules, Frank has
shown that the objects consist primarily of water.
"The Polar results definitely demonstrate that there are
objects entering the Earth's upper atmosphere that contain a
lot of water," commented Dr. Thomas M. Donahue, a noted
atmospheric physicist and professor at the University of
Michigan in Ann Arbor.
"The images show that we have a large population of
objects in the Earth's vicinity that have not been detected
before," said Frank, who designed the VIS instrument. "We
detect these objects at a rate that suggest Earth is being
bombarded by five to 30 small comets per minute, or thousands
per day." Comets are known to contain frozen water and are
sometimes called "dirty snowballs".
Frank's new observations are consistent with a
controversial theory he proposed in 1986 to explain the
existence of dark spots, which he termed "atmospheric holes",
in images of the sunlit atmosphere of the Earth. He first
detected these holes while analyzing data from an ultraviolet
imager flown on NASA's Dynamics Explorer 1 spacecraft. He
theorized that the holes were caused by the disintegration of
small icy comets in the upper atmosphere. The water vapor they
produce momentarily absorbs the ultraviolet solar radiation
scattered from oxygen atoms in the upper atmosphere, preventing
it from reaching his camera and resulting in a dark spot on the
image. These holes have diameters of 15 to 25 miles.
His theory of a new class of objects in the Solar System
ignited a wide-ranging controversy. Many colleagues discounted
the appearance of the holes as an instrumental problem. But
the new images from Polar also include observations of
atmospheric holes in much greater detail than before,
suggesting that they are real. "These results certainly
vindicate Lou Frank's earlier observations", said Donahue.
"These remarkable images cap a great first year for
Polar," added Dr. Robert Hoffman, Project Scientist for Polar,
which is operated and managed by NASA's Goddard Space Flight
Center, Greenbelt, MD. "I am pleased that Polar's instruments
were able to actually detect these objects streaking towards
the Earth and disintegrating into clouds of water vapor. They
give scientists a fascinating new and important phenomenon to
take into account in theories of Solar System evolution."
Images of the comets and the atmospheric holes can be
found on the World Wide Web at the following URL:
http://pao.gsfc.nasadot gov/gsfc/newsroom/flash/flash.htm
-end-
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End of meteorobs-digest V1 #457
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