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Re: (meteorobs) Excerpts from "CCNet 123/2001 - 22 November 2001"
Hi Robert,
The nswer to your riddle is simple, the moon has no atmosphere and so
relatively small particles hit at very high speeds, the earth has a thick
atmosphere (thank goodness) and a much larger partcle is required to survive
the heating which friction with the atmosphere generates, and reach the
earth's surface.
Hope this helps
Cheers
Peter D
----- Original Message -----
From: "Robert Hayden" <rhayden@carr-ferrell.com>
To: <meteorobs@atmob.org>
Sent: Thursday, December 06, 2001 7:22 AM
Subject: RE: (meteorobs) Excerpts from "CCNet 123/2001 - 22 November 2001"
> Riddle me this. If all meteors from comets are very fragile dust grains,
> explain the flashes on the moon. If, on one hand we readily accept that
the
> dust trails include chucks that are large enough to generate a flash on
the
> moon visable from Earth, isn't it plausible that similarly sized chunks
hit
> Indiana? Not that I would uncritically accept the story of the Yurans
> (presumably from the planet Yura), but the out-of-hand dismissal by
> astronomer Hammergren seems rash in view of the lunar observations.
>
> -Robert Hayden
>
> -----Original Message-----
> From: owner-meteorobs@atmob.org [mailto:owner-meteorobs@atmob.org]On
> Behalf Of Lew Gramer
> Sent: Wednesday, December 05, 2001 9:41 AM
> To: Meteor Observing Mailing List
> Subject: (meteorobs) Excerpts from "CCNet 123/2001 - 22 November 2001"
>
>
>
> ------- Forwarded Message
>
> From: Peiser Benny <B.J.Peiser@livjm.acdot uk>
> To: cambridge-conference <cambridge-conference@livjm.acdot uk>
> Subject: CCNet 123/2001 - 22 November 2001
> Date: Thu, 22 Nov 2001 10:31:08 -0000
>
> CCNet 123/2001 - 22 November 2001
> =================================
>
> "The chances these pieces are from the Leonid meteor shower are
> essentially zero," said Adler Planetarium astronomer Mark Hammergren
> Tuesday... Several factors make it unlikely that the rocks the Yurans
> found are meteorites, said Hammergren. "Meteors that come from comets are
> composed of very fragile dust," he said and the rocks found by the Yurans
> are far too large to have come from a comet. "Further," he said, "no
> meteorites have ever been recovered from a meteor shower, ever, and no
> meteorites have ever been tied to comets as their point of origin."
> --Chicago Tribune, 21 November 2001
>
>
> (1) ANOTHER FALSE ALARM? SPECTATORS NEARLY HIT BY METEOR SHOWER
> The Associated Press, 20 November 2001
>
> (2) SPACE ROCKS SLAM INTO INDIANA
> Chicago Sun Times, 21 November 2001
>
> (3) METEORITE CLAIM CALLED ROCKY: EXPERTS DISPUTE FIND IN INDIANA
> Chicago Tribune, 21 November 2001
>
> [...]
>
> (7) NASA PROBE TO BLAST INTO COMET
> Discovery News, 20 November 2001
>
> [...]
>
> (9) METEORITE CLAIM FROM LEONIDS?
> Phil Plait <badastro@badastronomy.com>
>
> [...]
>
> ==================
> (1) ANOTHER FALSE ALARM? SPECTATORS NEARLY HIT BY METEOR SHOWER
>
> >From The Associated Press, 20 November 2001
>
http://www.orlandosentinel.com/news/nationworld/sns-meteor.story?coll=sns%2D
> newsnation%2Dheadlines
>
> HIGHLAND, Ind. -- Laura Yuran and her son Jonathon got a closer look at
the
> Leonid meteor shower than they bargained for. Yuran and her 11-year-old
son
> believe they were nearly hit by chunks of the space rocks early Sunday
> morning.
>
> The two were watching the meteor shower outside their northwestern Indiana
> home about 4 a.m. when hail-like objects began pelting them, The Times of
> Munster reported today.
>
> As Laura walked toward the house to get her husband, Tom, a chunk of rock
> slammed to the ground near where she had been standing just moments
before.
>
> "It went, 'Boom!' and I screamed," Laura said. "Part of it hit the
driveway
> and the second part was embedded in the ground. I was afraid to touch it."
>
> Tom Yuran recovered two rocks, one of which he had to pull out of the
> ground, the newspaper said. The rocks, which are rust-colored on one side
> and silvery on the other, weigh a total of about two ounces.
>
> Jim Seevers, an astronomer from Chicago's Adler Planetarium, said the
rocks
> are likely meteorites from the Leonids. The rust color is "the fusion
> crust," he said, which results when the rock is seared by the earth's
> atmosphere.
>
> "The rock probably chipped off and the shiny silver they see is the
inside,"
> Seevers told The Times. "It's most likely iron and nickel."
>
> The Yurans contacted Chicago's Field Museum of Natural History, whose
> curator, Dr. Menache Wadhwa, asked them to bring one of the rocks for
> geologists to examine.
>
> "She said we're the only ones anywhere who have reported falling
meteorites
> from the Leonid meteor shower," Tom said.
>
> After the scientists are done examining the possible meteorites, Laura
said
> she hopes to put them in a display case and give it to her son for his
rock
> collection.
>
> Copyright 2001 Associated Press
>
> ==============
> (2) SPACE ROCKS SLAM INTO INDIANA
>
> >From Chicago Sun Times, 21 November 2001
> http://www.suntimes.com/output/news/cst-nws-meteor21.html
>
> BY ART GOLAB, STAFF REPORTER
>
> Watching the Leonid meteor shower early Sunday, Laura and Tom Yuran got a
> big surprise: Chunks of space rocks nearly hit them.
>
> "Go get your dad--it's hitting us!" Laura Yuran shouted to her 11-year-old
> son, Jonathan, as she ran for cover. Then a small chunk of rock slammed
into
> the driveway near where she'd been standing.
>
> ''It went, 'Boom!' and I screamed,'' the Highland, Ind., woman said.
''Part
> of it hit the driveway, and the second part was embedded in the ground. I
> was afraid to touch it.''
>
> Tom Yuran found his wife and son huddled under an awning on the steps of
the
> back porch. He gingerly approached the larger of the two objects.
>
> "I touched it with my finger, thinking it was going to be hot," he said.
"It
> was actually cold."
>
> One piece seemed to have broken off from the other. Both pieces were a
rusty
> brownish-orange on the outside, and silvery on the inside, where they had
> apparently split.
>
> The Yurans have an appointment today with Meenakshi Wadhwa, a Field Museum
> expert who will examine one of the objects. Wadhwa, curator of meteorites
in
> the museum's geology department, said the rust color could be the "fusion
> crust," which results when the atmosphere sears the rock.
>
> But she added that if it is a meteorite, it's unlikely to be associated
with
> the Leonid shower, which occurs once a year when the earth passes through
> the orbit of the comet Tempel-Tuttle. Despite the term "meteor shower,"
> Wadhwa said no actual meteorites have ever been found in conjunction with
a
> shower caused by a comet.
>
> "It could, however, be a coincidental meteor fall," she said. "Meteors
fall
> everywhere at random. . . . Every day, 50 tons of meteor fragments hit the
> earth, though most never make it to the surface."
>
> But some do. And collectors pay up to $25 a gram for meteorites, but the
> Yuran family doesn't plan on selling theirs. "I don't know if it has any
> monetary value," said Tom Yuran, 51. "But, for me, it definitely has a lot
> of sentimental value."
>
> Copyright 2001, Chicago Sun Times
>
> =============
> (3) METEORITE CLAIM CALLED ROCKY: EXPERTS DISPUTE FIND IN INDIANA
>
> >From Chicago Tribune, 21 November 2001
>
http://www.chicagotribune.com/news/printedition/chi-0111210078nov21.story?co
> ll=chi%2Dprintmetro%2Dhed
>
> By William Mullen
> Tribune staff reporter
>
> Two rocks that Highland, Ind., family members said fell into their yard
> early Sunday as they watched the spectacular Leonid meteor shower will be
> examined by meteorite experts Wednesday at the Field Museum.
>
> Tom and Laura Yuran are convinced the rocks are meteorites that rained
down
> on their yard from outer space during the meteor shower. Chicago area
> astronomers and geologists, however, are not convinced, at all.
>
> Laura Yuran said the larger of the two rocks, measuring about 2 by 1 1/2
> inches, slammed into a sidewalk about 4:30 a.m. Sunday. Later they found
> another, similar rock, with a crusty, rust-colored exterior and shiny
> metallic interior, measuring about 1 3/4 by 1 inches, in their lawn.
>
> "The chances these pieces are from the Leonid meteor shower are
essentially
> zero," said Adler Planetarium astronomer Mark Hammergren Tuesday.
>
> The Leonid meteor shower is a predictable phenomenon in which the Earth
> plows through trails of tiny debris left behind by the comet
Tempel-Tuttle,
> which passes near the Earth every 33 years.
>
> The debris, usually no larger than a grain of sand, burns intensely when
it
> strikes the atmosphere 60 to 70 miles above Earth, streaking visibly
across
> the night sky as shooting stars.
>
> Meteorites are meteors so big that they do not burn up entirely in the
> atmosphere and fall to earth.
>
> Laura Yuran said her son, Jonathon, 11, woke her up at 4 a.m. Sunday to go
> outside with him to watch the well-publicized meteor shower.
>
> "The sky looked like a beautiful light show festival," she said, "with
> beautiful streaks of light. It sounded like little pebbles were hitting
the
> ground all around us, like a hail storm.
>
> "I started walking to the house to get my husband to come out and look
when
> this thing fell like, Boom! It hit the sidewalk right by where I had just
> been standing. I screamed and my husband came running with a flashlight."
>
> The family soon found the two pieces of rock.
>
> "They are silver and gold and a rusted color," said Laura Yuran, a school
> maintenance worker, "that shine real prettylike, turned in a certain way,
> like little diamonds."
>
> Several factors make it unlikely that the rocks the Yurans found are
> meteorites, said Hammergren.
>
> "Meteors that come from comets are composed of very fragile dust," he said
> and the rocks found by the Yurans are far too large to have come from a
> comet.
>
> "Further," he said, "no meteorites have ever been recovered from a meteor
> shower, ever, and no meteorites have ever been tied to comets as their
point
> of origin."
>
> Most meteorites are pieces of asteroids crashing through the Earth's
> atmosphere, he said. A very rare few are pieces of rock that exploded off
> the surface of Mars or the moon from the impact of striking asteroids,
> sending them flying to Earth.
>
> Meenakshi Wadhwa, a Field Museum geologist who has recovered Mars
meteorites
> from expeditions to snowfields in Antarctica, said she will examine the
> Yurans' rocks when they bring them to her laboratory at the museum
> Wednesday.
>
> "It seems improbable that they could be meteorites," she said, "but it is
> impossible to say until I can see them.
>
> "Certainly it seems impossible that they could be associated with the
Leonid
> meteors. The chance that they are meteorites that fell coincidentally from
> another source during the meteor shower seems very unlikely too."
>
> As word of the falling rocks spread Tuesday, the Yurans said they were
> inundated by requests for media interviews, including scheduled
appearances
> Wednesday via remote hookups with three national morning television news
> shows.
>
> "Some people have asked if we were being hoaxed by some jokers throwing
> rocks into our yard," said Laura Yuran, "but that couldn't be. We got up
on
> the spur of the moment, so nobody could have known we were going to be
> there.
>
> "My God, if one of those things had hit one of us in the head, we wouldn't
> be here now."
>
> Copyright ) 2001, Chicago Tribune
>
> =============
> (7) NASA PROBE TO BLAST INTO COMET
>
> >From Discovery News, 20 November 2001
> http://dsc.discovery.com/news/briefs/20011119/asteroid.html
>
> By Irene Brown, Discovery News
>
> Nov. 20 - Robotic probes have flown by asteroids and comets, collected
> samples for return to Earth and even landed on one of the small primordial
> worlds, but a new mission under development by NASA takes solar system
> exploration a step farther: into a comet's heart.
>
> Called Deep Impact, the spacecraft is designed to slam into the surface of
> comet Tempel 1, creating a crater larger than a football field and deeper
> than a seven-story building. Its primary scientific theme is to understand
> the differences between the interior of a comet's nucleus and its surface.
>
> Comets are interesting to scientists because they contain material, often
> ice and dust, from the original formation of the solar system. As comets
> near the sun, the ice melts and releases dust particles: the comet's tail.
> Many comets far from the sun are hard to tell apart from asteroids, which
> are made of rock, and there's currently no way to properly identify the
> imposters.
>
> The information is important for several reasons, including the practical
> though improbable scenario that at some time in the future, we will need
to
> deflect a comet or asteroid on a collision course with Earth. Knowing
what's
> inside the threatening comet or asteroid will be crucial to developing
> technologies to alter its path.
>
> The idea to probe beneath a comet's icy surface dates back more than 20
> years. Data from a European probe dispatched to Halley's Comet revealed a
> mysterious black core, which puzzled researchers.
>
> "We became increasingly curious as to just how this black layer
> accumulated," said Alan Delamere, who is overseeing development of Deep
> Impact's instruments and systems for Ball Aerospace and Technologies
Corp.,
> which is building the spacecraft for NASA. "We suspect that as the comet's
> ice dissipates, dust is left, which becomes a loose, outer crust
insulating
> the trapped, inner comet."
>
> The probe is scheduled for launch in January 2004 and hit the comet on
July
> 4, 2005. With a variety of science instruments and imagers, the spacecraft
> will study how the crater is formed and what lies beneath its outer
surface.
>
>
> "The mission is completely different, " said astronomer Michael A'Hearn,
> with the University of Maryland. "It is a real experiment in which we do
> something to another body in the solar system and see how it reacts."
>
> NASA approved the $280 million mission in May following an 18-month
> preliminary design review.
>
> Deep Impact will be equipped with a 770-pound copper impactor that will
> separate from the spacecraft a day before pounding into the comet. A
camera
> on the impactor is expected to relay close-up images of the comet's
surface
> until the crash. Cameras on the mother ship itself will then record the
> impact and image the interior of the comet.
>
> "The biggest challenge of the mission is making sure we have a very stable
> flyby spacecraft that is able to track the event as the impactor reaches
the
> comet," said Delamere.
>
> "We'll have 800 seconds or so to gather images and data. All this makes
the
> flyby spacecraft critical because it will be traveling through a hazardous
> area filled with cometary material - and fragments that could destroy the
> spacecraft."
>
> NASA's last close encounter with a comet was Deep Space 1's flyby of Comet
> Borrelly in September. In February, the NEAR science probe successfully
> landed on an asteroid.
>
> In addition to Deep Impact, NASA is planning to launch the Contour mission
> to study at least two comets close-up, while the European Space Agency is
> gearing up for its Rosetta mission to land on a comet and scratch its
> surface. Already en route to a comet is NASA's Stardust mission, which is
to
> pluck samples of comet dust and return them to Earth.
>
> Copyright ) 2001 Discovery Communications Inc.
>
> ============================
> * LETTERS TO THE MODERATOR *
> ============================
>
> (9) METEORITE CLAIM FROM LEONIDS?
>
> >From Phil Plait <badastro@badastronomy.com>
>
> Benny-
>
> While watching TV this morning, I caught the tail end of a report on NBC's
> Today Show about a family who think some meteorites hit their house the
> night of the Leonids peak. They even had samples they showed briefly
(which
> looked to me like sedimentary rocks, and not meteorites). They were from
> Illinois, and said scientists from the Field museum would be looking at
> their samples. I have not been able to find any more info on this, even on
> the Today Show website. I was hoping
> some of the people who read CCNet may know more. I suspect this will turn
> out just like the case of a New Hampshire couple who thought they got hit
> last December. That turned out to be fireworks or something similar. If
> anyone has more info, please email me at badastro@badastronomy.com.
Thanks!
>
> -Phil Plait
>
> * * * * * The Bad Astronomer * * * *
>
> Phil Plait badastro@badastronomy.com
> The Bad Astronomy Web Page: http://www.badastronomy.com
>
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> If you are interested in complete links on the 2001 LEONIDS, see:
> http://www.meteorobs.org/storms.html
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> The archive and Web site for our list is at http://www.meteorobs.org
> If you are interested in complete links on the 2001 LEONIDS, see:
> http://www.meteorobs.org/storms.html
> To stop getting email from the 'meteorobs' list, use the Web form at:
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The archive and Web site for our list is at http://www.meteorobs.org
If you are interested in complete links on the 2001 LEONIDS, see:
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