CCNet, 5 October 1999

    EARTH IN 2042/2050
    Benny J Peiser <>

     Steve Chesley <>

    Jacqueline Mitton <>

    Science-Week <>



From Malcolm Miller <>
Dear Benny,

The astronomy books I read as a child (a long time ago!) were full
of the name of E E Barnard, and of beautiful photographs made by
him. I've always admired him, as a really grteat observer who was
always at the cutting edge, using the best instruments to the limit
of their capabilities at that time. I was thrilled by Brian
Marsden's article describing the history of Barnard's 1904
observation. Who could not be impressed with the accuracy of his
micrometer measurements as shown by the near-perfect fit with
sophisticated observations in the 90s?


   By Malcolm Miller <>

   E E Barnard had eagle eyes; who else would catalogue*
   the things that can't be seen?  No-one can doubt
   he was the greatest observer of his time.
   The great refractors were his tools, masterpieces
   of the opticians' art whose like will not be made again.
   More than a hundred years ago he was the first
   to find a comet with new-fangled photographs,
   and scanned the Milky Way with portrait lenses,
   finding new clouds of stars and others that were dark
   and bear his name forever in the charted sky.
   Seeking a mislaid satellite - he'd found a few himself -
   he searched near Saturn and found a tiny interloper,
   measured its place with customary precision,
   and saved the precious data for posterity.
   Nearly a century has passed, and now we know
   instead of little Phoebe he'd seen the vanguard
   of the Trojans, those asteroids providing celestial
   honour guards for mighty Jupiter, following and preceding
   in his orbit the way Lagrange had forecast
   more than another century before.
   More honour to Barnard, observer without equal!


   * Barnard's Catalogue of  182 Dark Clouds in the Milky Way

       EARTH IN 2042/2050

From Benny J Peiser <>

In a low-key message posted yesterday on the Minor Planet Mailing List,
Steve Chesley announced that he and his colleagues at Pisa University have
identified a potential danger that asteroid 1999 RM45 might impact
with Earth in 2042 or 2050. According to their calculations, however,
each impact scenario has very low probabilities (less than 10^-8).

Whilst the calculated impact possibilities after six days of
observations are extremely small, we know from the recent experience
with asteroid 1999 AN10 that this picture can change at any time
given more observational data. This is why Chesley's call for
follow-up oberservations is important if we wish to rule out the
current or even more probable impact scenarios for good.

After the decisive case study of asteroid 1997 XF11 and its potential
impact date in 2040 (and other years) came asteroid 1999 AN10 with
impact possibilities in 2044 (and other years), and the weaker case
of 1998 OX4. This makes 1999 RM45 only the fourth object that has (or
has had) any potential impact danger. What is really needed, though,
is to rule out any such future danger. Brian Marsden did that with
1997 XF11 and Andrea Milani et al. with 1999 AN10 (not entirely in
this case, for it may still have problems for us in the twenty-second
century and onward). 1998 OX4, as CCNet subscribers know, is of
course lost.

Given the faintness of RM45, it would appear that the most important
need for the NEO search community is to have at its disposal a large
telescope (specifically dedicated for NEO searches) which is powerful
enough to search faint objects such as RM45 (i.e. mag 22-23-24) when
such observations are *really* needed. With a record 9 new NEOs
discovered in the last few days alone, it is clear that the need for
adequate follow-up instrumentation will become even more relevant in
the near future.

On a slightly different note it is interesting to see that the Torino
Hazard Scale has been virtually irrelevant in this latest
case of a cosmic hazard. Even in the event of an increased impact
probability of asteroid 1999 RM45, the only relevant information the
public wants to know is what future observations can tell us about the
asteroid's actual orbit. It goes without saying that this is exactly
what we want to know about asteroid 1999 RM45.

Benny J Peiser


From Steve Chesley <>
[as posted on the Minor Planet Mailing List, 4 October 1999]

I have added another potential impactor to the NEODyS Risk Page
<> and it is in critical
need of follow up. We have identified potential collision solutions
for 1999 RM45 in 2042 and 2050, each with very low probabilities
(less than 10^-8). Such a very low probability of impact means that
the risk posed by RM45 is not of serious concern to the public at
large; however, I think it is very important for the NEO community to
take all reasonable and practical steps to ensure that this PHA is
not lost, or at least to improve the orbit as much as possible before
it does become lost.

1999 RM45 was discovered by LINEAR on September 14th, and observed 38
times over the next six days. It has not been observed since
September 20th. The following table provides a crude summary of its
brightness and 3-sigma uncertainty on the sky in the coming weeks.

Date         Magnitude        Uncertainty(arcmin)
Now            19.3            +/- 0.5
Mid-Oct.       20              +/- 2
Late-Oct.      21              +/- 5
Mid-Nov.       22              +/- 8

A detailed ephemeris can be obtained from the usual suspects,
including NEODyS. One note of caution, the estimate of the brightness
has a formal uncertainty of +/- 0.7 magnitudes.

It is clear that this is a difficult target, and is already out of
reach of many amateur setups, but I expect that it still is a
reasonable target for numerous observers during the present dark run.
In November it will probably limited to very large (read
professional) observatories.

An ephemeris based on the nominal orbit indicates that this object
will not be observable at brighter than 23rd magnitude until 2008, at
which point it will already be lost by a full revolution around the
sun.  However, the orbit is so uncertain at the present time that it
may be observable much sooner than 2008, and orbital improvements now
could facilitate a recovery much earlier. Moreover, the two collision
solutions we have found are quite far from nominal, thus it is very
reasonable to expect that these impacts may be ruled out simply by
extending the arc at this apparition.

I should be clear that I am not suggesting that we need to devote an
inordinate amount of follow up resources to this target; there is
obviously a point of diminishing returns. But on the other hand, the
fact that this object may not be observable for a very long time, and
that it is a PHA with a nonzero probability of collision tells me
that this object deserves special attention. Typically it is most
efficient to simply extend the arc as long as possible with sparse
observations, but in this case that may not be enough. In such a
situation, it is valuable to have a more dense set of observations
along the available arc to minimize the effect of random errors, and
from several observatories to minimize the effect of systematic

Steve Chesley
University of Pisa


From Jacqueline Mitton <>


Date: 4 October 1999

Ref. PN 99/31
Issued by: Dr Jacqueline Mitton
RAS Press Officer
Office & home phone: Cambridge ((0)1223) 564914
FAX: Cambridge ((0)1223) 572892

RAS Web:


Recent results about the Moon, and prospects for new initiatives,
future research and exploration of our nearest neighbour in space
will be the subject of a one-day discussion meeting in London as part
of the Royal Astronomical Society's regular monthly programme.

Media representatives are welcome to attend. The meeting is in the
Lecture Theatre of the Geological Society in Burlington House,
Piccadilly, London. Most speakers are expected to be available for
interview during the lunch break, immediately after the meeting, or
by prior arrangement. (On the day of the meeting, please use
Jacqueline Mitton's mobile phone number, 0370 386133.)

An outline of the programme, summaries and contact details for
speakers (where available) are given below.


Discussion meeting at the



Organised by

Dr Sarah Dunkin (University College London, phone 0171 504 2577,


Dr Manuel Grande (Rutherford Appleton Laboratory, phone: 01235 446501,

10.00 Registration (no fee)/Coffee

10.30 Introduction by Dr Manuel Grande

10.35 Prof. Lionel Wilson (University of Lancaster, phone: 01524 593889,
secretary 01524 594200, e-mail:

          "Changing views of the origin and evolution of the Moon
            - a 30-year perspective"

Despite the passage of 30 years, interpretation of the data collected
by the Apollo and Luna missions is continuing, and we still await a
complete picture of the evolution of the Moon's interior. Combining
lunar data with information on asteroids obtained via meteorites
helps our understanding.

11.00 Vera Fernandes (Dept. of Earth Sciences, University of Manchester,
phone: 0161 275 3941, e-mail:

          "Lunar samples and their contribution to lunar geology"

This talk will review current ideas about the Moon's origin, its
geological history, volcanism and cratering. It will include the
implication of recent work done on Apollo 14 'green glass' samples
for the composition of the lunar mantle and the dating of lunar rock
and lunar meteorites.

11.15 Dr Ian Franchi (The Open University, e-mail

      "Nitrogen in lunar soils - further progress on solving the

11.35 Dr Urs Mall (Max Planck Institut für Aeronomie, Lindau, Germany)

         "Pickup Ion Spectroscopy, a probe for the lunar surface"

11.55 Dr Chris Owen (Mullard Space Science Laboratory, University
College London, Phone: 01483 274111)

          "Solar wind interaction with the Moon

12.15 Sandra Jeffers (Armagh Observatory, phone: 028 3752 2928,

        "Comparing lunar crater and small near-Earth asteroid size

12.30 Dr Sarah Dunkin (University College London, phone: 0171 504
2577, e-mail:

          "New views of the Moon Lunar Initiative:
             A report from the second workshop"

There is currently an initiative to bring together specialists on
lunar samples and lunar remote sensing scientists so each can
understand the others' work more fully. This talk will report on a
recent workshop and invite UK scientists to participate in a major
Lunar Initiative publication.

12.45 - 13.25 Lunch break

13.45 David Heather (University College London, phone: 0171 504 2577,

          "The Clementine Mission & Results"

A review of the primary results so far obtained through analysis of
the data returned by the Clementine spacecraft. The mission provided
the first global datasets of the Moon, including multispectral,
topographic, crustal thickness, and gravity information. It also
carried the radar that first hinted of the presence of water at the
lunar poles.

14.00 Dr Sylvestre Maurice (Observatoire Midi-Pyrenees, Toulouse, France)

           "Water and geology: New results from Lunar Prospector"

14.25 Dr Bernard Foing (ESTEC, The Netherlands, e-mail

          "The ESA SMART-1 Mission to the Moon"

14.50 Dr Manuel Grande (Rutherford Appleton Laboratory, phone: 01235
446501, e-mail:

           "D-CIXS, and X-ray spectrometer for the SMART-1 mission"

This UK-led instrument is likely to be included in the payload of
ESA's prospective lunar mission SMART-1.

15.10 Prof. Carl Murray (Queen Mary and Westfield College London,
phone: 0171 975-5456, e-mail:

            "Cassini's flyby of the Moon: latest results"

This talk will cover the recent lunar flyby of the Cassini-Huygens
mission to Saturn, the reasons for acquiring the calibration images
(138 in total) and the on-going work that Queen Mary and Westfield
College is doing on software for the Imaging Science Subsystem (ISS)
calibration. When calibration is complete, the lunar images are
expected to yield useful lunar science. Forthcoming Cassini
activities (i.e. hopefully a distant flyby of an asteroid in January
2000 and the Jupiter flyby in December 2000) will also be mentioned.

15.30 End of meeting


From Science-Week <>


Lewis Wolpert (University College London, UK), in a "commentary"
article, considers the classic question whether science is dangerous,
the author making the following points:

1) The idea that knowledge is dangerous is deeply embedded in our
culture. Indeed, Western literature is filled with images of
scientists meddling with nature with disastrous results. Scientists
are portrayed as a soulless group, unconcerned with ethical issues.

2) The social obligations that scientists have, as distinct from
those responsibilities they share with all citizens, come from
scientists having access to specialized knowledge of how the world
works, knowledge that is not easily accessible to others. The
obligation of scientists is to make public any social implications of
their work and its technological applications, and to give some
assessment of the reliability of their work. In most areas of
science, it matters little whether a particular theory is right or
wrong, but in some areas, such as human and plant genetics, it
matters a great deal.

3) The most clear case of immorality in scientific research was the
eugenics movement. The scientific assumptions behind this movement
were crucial: that most human attributes (desirable and undesirable)
are inherited. The scientists concerned completely failed to give an
assessment of the reliability of their ideas or sufficiently to
consider the implications of their ideas. On the contrary, and even
more blameworthy, their conclusions seem to have been driven by what
they saw as desirable social implications. In contrast, the Allied
scientists who built the atomic bomb behaved morally, and fulfilled
their social obligations by informing their governments about the
implications of atomic theory. The decision to build the bomb was
taken by politicians, not scientists.

4) The very term "genetic engineering" conjures up the image of
Frankenstein and his monster. The media are aware of this and often
report what can be regarded as genetic pornography -- reports dressed
up to titillate and frighten. Newspapers print sensational and
unjustifiable headlines such as the "Frankenstein foods" idiocy
surrounding genetically modified organisms in the UK..

5) Bioethics is a growth industry that purports to address questions
concerning the dangers to society posed by biological science. But
one should regard this field with caution, as bioethicists have a
vested interest in finding difficulties.

6) Are there areas of research that are so socially sensitive that
they should be avoided, even proscribed? Once one begins to censor
the acquisition of objective knowledge, one is on the most slippery
edge of all. Scientists cannot easily predict the social and
technological implications of research, as is demonstrated by
numerous examples in the history of science and technology.

7) The author concludes: "National and international councils that
can assess the ethical issues relating to the applications of science
and promote public debate are no doubt valuable. But one wonders what
such a committee would have said if the public had been offered a
convenient form of transport, but at the cost, in the United Kingdom
alone, of more than 3000 lives per year, a quarter of a million
injured and the untold damage of pollution. Where are the
Lewis Wolpert: Is science dangerous?
(Nature 25 Mar 99 398:281)
QY: Lewis Wolpert []
Copyright (c) 1999 ScienceWeek
All Rights Reserved



In 1833, people woke to a sky that seemed ablaze. The hubbub was over
the Leonid meteor shower, set for a possibly grand encore Nov. 17.

By Wil Milan for

The Earth may be about to witness the greatest show ever visible in
our skies, a very rare event which, if it comes off, will be the
headline of every newspaper, cause many people to panic, and leave
everyone in awe. But to understand what is happening, let’s first
talk about bees:

Bees on the windshield

Imagine that you are driving at 60 miles per hour down a rural 
highway. Unbeknownst to you, a swarm of bees is crossing the highway
just ahead of you. In the blink of an eye your vehicle plows right
through the middle of the swarm, and in that instant dozens of bees
are splattered over the front of your car.

Had you arrived at that point on the highway only seconds later, you
would have encountered only the trailing portion of the swarm and
struck only a few bees. Had you been even later than that you might
only have hit one or two stragglers and missed the main swarm

Bigger and faster "bees"

Striking a few bees with your car is not a big deal, and we wouldn’t
give it much thought. But much the same thing happens on much larger
scale, not with your car, but with the entire Earth. The Earth
travels around the Sun at a tremendous speed, over 100,000 kilometers
per hour (about 67,000 miles per hour or about 18 miles per second).

The space through which the Earth travels is largely empty, so there
is not much for the Earth to hit as it speeds along. But it is not
totally empty; there are scattered bits of dust and the occasional
little rock, and when the Earth collides with one the dust grain or
small rock plows into the atmosphere at a combined speed sometimes
reaching hundreds of kilometers per second.

At that speed the friction of the object passing through the
atmosphere is so intense that the tiny object is instantly heated to
many thousands of degrees. The heat is so intense that the tiny
grains of dust are completely burned up in a fraction of a second,
leaving only a momentary bright streak and a bit of vaporized ash
floating in the air. If it were night and had you been looking in the
sky at that moment you would have seen what is sometimes called a
"shooting star," the flash of a meteor burning itself out in the
upper atmosphere. On any given night under dark skies you can see a
dozen or more bright meteors, heaven’s reward for having your eyes on
the sky.

Bigger swarms

But sometimes the Earth encounters not just random bits of dust, but
a more concentrated swarm. In those cases many more than a dozen
meteors will be seen, and the rate at which meteors are seen may rise
to 30, 50, even over 100 per hour. These are called meteor showers,
and they are recurring events that take place at the same time each
year. Thus the Lyrids meteor shower occurs in April 21-22 of each
year, the Perseids on August 11-12, the Leonids take place the night
of Nov. 17 each year, the Geminids on December 13-14, and so on.

(The names "Lyrids," "Perseids," etc. refer to the constellation from
which the meteors appear to originate. The Lyrids appear to come
from the constellation Lyra, the Perseids from Perseus, etc. They
don’t really come from the constellation, of course; it’s only an
optical illusion due to the combined directions of travel of the
meteors and the Earth.)

The reason that the dates of meteor showers remain the same from year
to year is that on those dates the Earth reaches points in its orbit
where there are known concentrations of space dust and debris. These
bits of dust and debris are not stationary – nothing in space is
truly stationary -- but they are in orbit about the Sun in a
racetrack pattern, just as the Earth follows its own "racetrack"
around the Sun. But because the two "racetracks" cross each other,
each year when the Earth reaches the point where the orbits of the
Earth and the dust swarm cross each other, the Earth plows through
the thin trail of dust and for a few hours we see more meteors in the

The source of the swarms

What causes these "racetrack" trails of dust is comets. Comets are
clumps of dust and ice a few miles across and they are very loosely
held together. As they travel in their orbits about the Sun they are
continually scattering dust and debris in their wake, and over time
the path of their orbits become one continuous trail of thin dust and
debris. The orbits of most comets don’t cross the Earth’s orbit, but
when one does then the Earth, in subsequent years, will cross the dust
trail of the comet and a meteor shower will occur at that point each

Thus it is that every meteor shower is believed to be associated with
a comet. In some cases the parent comet of a meteor shower can be
clearly identified: The Perseids appear to be associated with comet
Swift-Tuttle, the Leonids with comet Tempel-Tuttle, and both the
Orionids and Eta Aquarids meteor showers appear to be associated with
Comet Halley (because the Earth crosses Halley’s orbit in two
places). In some cases the parent comet is unknown and believed to be
long extinct, but the dust trail remains to mark its former orbit.

A near miss

So what would happen if the Earth did not cross the comet’s trail far
back from the comet, but rather very close behind the comet? In other
words, what if we crossed the comet’s orbit right after the comet had
just passed? Obviously we would be passing fairly close to the comet,
and there would be more comet dust and debris to encounter.

What happens in those cases is that the meteor shower that would
normally take place becomes much more intense. The meteor rate may
increase from one or two a minute to tens or hundreds of meteors per
minute, and there have been instances when hundreds of meteors per
second have been seen for short periods of time.

Those very rare cases where the rate reaches dozens or hundreds per
minute are known as "meteor storms," and the meteor storm that is
credited with launching the modern study of meteors occurred during
the Leonids meteor shower on the night of Nov. 12-13, 1833. Meteor
storms had been observed before, and just the year before the Leonids
had put on a spectacular show, with one observer in Boston counting
over 8,000 meteors in only 15 minutes.

But what occurred when the Leonids returned in 1833 was far beyond
what anyone had ever seen or even imagined possible. For several
hours over the United States there was a continual blaze of thousands
and thousands of meteors at a time. One estimate was that over
240,000 meteors fell during that period, so many meteors in the sky
at a time that many people were woken from their beds and stared at
the sky in panic, believing the sky to be on fire. Many feared that
it was the end of the world and dreaded what they would see at

At daybreak, of course, everything was back to normal. Hollywood
movies notwithstanding, meteors typically vaporize in the atmosphere,
a few drop harmlessly to the ground, and there is only one known
incident in history when a meteor struck someone (and she only got a
bruise from it). The only living thing ever known to have been killed
by a meteor was a very unlucky dog in Egypt many years ago. You
are more likely to be struck by lightning seven times in a row than to
be hit by a meteor.

The show returns

When the Leonids returned in 1834 it was again a good meteor show,
but nothing like the sky-on-fire spectacle of 1833. The great meteor
storm was back 33 years later in 1866. Astronomers predicted that
the meteor storm would return every 33 years, but it failed to
materialize in 1899 or 1933.

Astronomers began to think that perhaps the great meteor storms would
not be repeated, but right on time in 1966 the great meteor storm was
back, particularly over the western United States. During a peak
period which lasted less than an hour there were hundreds of meteors
in the sky at once, and rates as high as 40 per second were observed.

Orbital observations by then had pinpointed the source of the meteor
storm as Comet Tempel-Tuttle, which has a 33-year orbit. Those
occasions when the meteor storm occurred were linked with times when
the Earth had passed close behind the comet in its orbit. But the
theory is not fully worked out; though there clearly is a link with
the comet’s position, there is no good explanation why there was no
meteor shower when we passed close to the comet in 1899 and 1933.

33 years later …

You’ve probably already done the math: The last Leonids meteor storm
was in 1966, it appears to take place at 33-year intervals, and 33
years later is this year, 1999. And so it is that astronomers
everywhere are eagerly awaiting the night of Nov. 17/18 of this year.
If the pattern holds, on that night we may again witness perhaps the
grandest spectacle in the sky, a great meteor storm that for a few
minutes to a few hours sets the sky on fire with thousands of meteors
and fireballs.

There is already some evidence of a build-up in Leonids. Though
nowhere near the rate of a true meteor storm, last year’s Leonids
meteor shower was much stronger than usual, with rates several times
the norm. Several locations around the world reported rates of
several hundred meteors per hour. At my location in Arizona several
of us were treated a great show; as daybreak approached the rate
was increasing and we could often seen several meteors in the air at
once. Still not a meteor storm, but a great harbinger of a great event in

How to see the show

The Leonids meteor show will be visible the night of Nov. 17 through
the early hours of the morning of Nov. 18, and to see the event you
need only one thing: dark skies. Bright city skies make it impossible
to see most meteors, so you’ll need to head out to the country where
the skies are clear and dark. No equipment of any kind is required,
and in fact telescopes and binoculars only hinder the view. Bring
warm clothes, a comfortable chair, then sit back and enjoy the show,
but do be prepared to stay awake past midnight. There is usually
little activity in the early evening, but after midnight (when the
part of the Earth where you are located is on the "front" of the
Earth as it travels around the Sun) the activity will pick up and
often accelerate as daybreak approaches.

There is no guarantee that the 1999 Leonids will be a spectacular
meteor storm as in 1966 and 1833, but if the pattern holds, this is
the year it is most likely to occur. Even if the great meteor storm
doesn’t develop, some kind of meteor shower is guaranteed to occur,
and that alone is worth the watching. Any night under the stars is a
great experience, and enjoying a meteor shower with a few friends and
warm drinks under a clear sky is one of the finest ways to spend a
few hours. A meteor shower is a fireworks show that Man can never
match, and if the great meteor storm does develop, for most people it
will be the most memorable event they have ever seen.

Enjoy the show, and don’t forget to bring the hot chocolate.

Copyright 1999,

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