PLEASE NOTE:


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Date sent: Thu, 05 Jun 1997 14:12:10 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: NOW IT'S A NEW MINI-PLANET
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL

BELIEVE IT OR NOT: ASTRONOMERS CLAIM TO HAVE FOUND NEW MINI-PLANET
AND PREDICT THAT THERE ARE 6000 OTHERS IN OUR SOLAR SYSTEM

There is just nothing like it (... well, almost, if you know what I
mean). Not even the excellent performance of the English soccer
team yesterday evening against Italy (the first win in 20 years;
apologies to our Italian list members) can compare to the speed
and excitement with which new astronomical discoveries continue to
challenge our dearly held world view. The storm over the recent
NASA story about newly discovered mini-comets has hardly calmed
down, there is another claim for a new discovery which - it is
suggested - could lead to revisions of astronomy textbooks. This
time, though, we are told that a new mini-planet has been
discovered in our solar system, a new object of a category of which
there might be as many as ~6500 other - none of which has ever been
detected yet.

Benny J Peiser
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from: THE TIMES, 5 June 1997

AN OBJECT ONE 25th THE SIZE OF THE EARTH MAY FORCE ASTRONOMERS TO
RETHINK HISTORY OF OUR SOLAR SYSTEM

SCIENTISTS FIND NEW PLANET BEYOND ORBIT OF NEPTUNE

By Nigel Hawkes, Science Editor

Astronomers have discovered a mini-planet at the edge of the solar
system which may change our thinking on how the planets evolved.
More than 300 miles in diameter, the planetesimal is the brightest
object to be found beyond the orbit of Neptune since the discovery
of Pluto in 1930.

Given the designation 1996TL66, the new object is probably one of
many, according to its discoverers, Jane Luu of the
Harvard-Smithsonian Center for Astrophysics in Cambridge,
Massachusetts, and colleagues. They say it is the first example of
a new class of objects scattered throughout the outer solar system,
whose total mass is between two and eight times greater than the
mass of those in the Kuiper Belt, a swarm of bodies moving around
the Sun in orbits beyond Neptune.

If so, the finding has implications for the history of the solar
system because it suggests that the primordial mass of material
spinning around the Sun, from which the planets condensed, must
have been much more extensive than previously assumed.

The mini-planet takes 800 years to revolve around the Sun and its
highly elliptical orbit means that it spends most of its time way
beyond the outer limits of the solar system, where it is too small
to be visible. It can be seen only during the part of its orbit
when it is nearest to the Sun - for 100 years in every 800. At its
closest approach it is 35 times as far from the Sun as the Earth,
placing it between Neptune and Pluto. It is roughly one 25th the
size of Earth.

The object was found using a sensitive detector mounted on a
telescope at the University of Hawaii, and a computer program to
examine successive images of the same region and detect moving
objects. It was found after scanning only a very small area,
suggesting, the team says in NATURE magazine, that "unless we are
improbably lucky, it is merely the first detected of a larger
population of similar bodies".

There are likely to be at least 800 such objects and perhaps as
many as 6,400, the team calculates, most of which will be too small
to be visible.

The origin of the object appears to have been the Kuiper Belt.
David Hewitt and Dr Luu, who are both involved in the discovery,
found the first of the Kuiper objects in 1992. But that object, and
about another three dozen that have been found subsequently, occupy
near-circular orbits around the Sun.

Even further out, beyond the limits of the solar system, there is a
second belt of objects, the Oort cloud, from which comets
originate.

This new planetesimal belongs to neither of these two classes. The
team speculates that it may originally have been in the Kuiper
Belt, but was perturbed by a close pass by Neptune or by another
planetesimal, and placed in its present eccentric orbit.

The new object will be given a name, chosen by the discoverers,
once it has been clearly established that it is new, and not merely
a new sighting of a previously identified object. The names are
judged by a nine-person panel of professional astronomers called
the Small Bodies Names Committee of the International Astronomical
Union.

While many discoverers choose to name minor planets after
themselves or figures from literature or mythology, other more
exotic names are not frowned upon. A minor planet found in 1972 is
called Pele, for example, while others are called Nefertiti, Don
Quixote, Magellan and Pocahontas. A dozen have been named after pop
stars: all The Beatles are included, as well as Eric Clapton and
Frank Zappa.



CCCMENU CCC for 1997

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