Jan
18, 2007
The Explosive Demise of Comet Linear
(Originally posted on May 20, 2005)
When comet Linear blew apart in the summer of 2000, the event
underscored the failure of popular comet theory to anticipate the
actual attributes and behavior of comets. Linear was not the “dirty
snowball” of modern comet lore.
In September
1999, the LINEAR telescope in New Mexico detected a comet
out beyond the orbit of Jupiter, speeding toward the Sun.
Because it was the first instrument to see it, the comet
received its name from the telescope.
Linear was
estimated to be about a mile wide. As it approached its
perihelion in July 2000, many telescopes—including the
Hubble Space Telescope—had the comet in clear view. Then
strange things began to happen. On July 5, Linear brightened
by more than 50 percent in just four hours. It was throwing
off large quantities of dust—much more dust than the
expected water or other volatiles.
Next, a chunk of
the nucleus tore away and “blew” back into the tail where it
continued to disintegrate, as can be seen in the Hubble
Space Telescope images
here.
Then, on July
14, the orbiting Chandra X-ray Observatory discovered that
the “dirty snowball” was generating X-rays! (Photo above
left).
The mystery of
comet X-rays had begun only four years earlier. It had
always been supposed that these “frozen” objects would
exhibit none of the high-energy reactions necessary to
produce X-rays. But then on March 27, 1996, the ROSAT
satellite recorded X-rays on the sunlit side of Comet
Hyakutake. A NASA report on Hyakutake notes that astronomers
“were shocked by what they saw. ROSAT images revealed a
crescent-shaped region of X-ray emission around the comet
1000 times more intense than anyone had predicted!” For four
years the source of the X-rays remained a mystery, as the
ROSAT, EUVE and BeppoSAX satellites detected X-rays and
extreme ultraviolet radiation from more than half-a-dozen
comets, including Hale-Bopp.
But now, Linear
was giving astronomers some telling clues, and the
implications were electrical. Chandra viewed the
comet Linear repeatedly over a two-hour period. The
Observatory’s press release reported that the X-rays were
being produced “by collisions of ions racing away from the
sun (solar wind) with gas in the comet. In the collision the
solar ion captures an electron from a cometary atom into a
high-energy state. The solar ion then kicks out an X-ray as
the electron drops to a lower energy state”. The authors of
the news release do not appear to have known that, in the
electric model of comets, this was a
predictable reaction between the
negatively charged plasma of the comet’s coma and the
positively charged ions in the solar wind—nature’s efficient
means of X-ray production.
As seen in the
X-ray image of Linear above, and as the electric model would
anticipate, the X-ray production occurred at the interface
of the negatively charged cometary plasma with the
positively charged particles of the solar wind.
A NASA Science
News story on Linear thus reports, “When ions from the Sun
blow past a comet, their strong positive charge attracts
negatively-charged electrons from cometary atoms and
molecules. In effect, the ions try to neutralize their own
unbalanced charge by stealing electrons from the comet”. The
report states that electrons contributed by the comet, in
uniting with the positive ions from the solar wind, “emit
X-rays as they cascade from high-energy to low-energy ionic
orbits. This process, called a ‘charge exchange reaction’,
was first proposed in 1997 as a possible reason for cometary
X-rays”.
But the NASA
report assumes, in contradiction of evidence gathered for
almost twenty years, that it is neutral atoms in the
coma that contribute the electrons. More reasonable is the
contention of the electric theorists that comets are the
cathodes, or negatively charged objects, in an electrical
exchange with the Sun. In this view, excess electrons will
combine preferentially with the positive ions in the solar
wind. In fact, the excess of electrons in a cometary coma
was first noted in 1986, when the Giotto spacecraft detected
an abundance of negatively charged atoms in the inner coma
of Comet Halley.
Also, as a
matter of historical record, the NASA statement that “charge
exchange reaction” was first proposed in 1997 misses the
mark by a century. The electric comet hypothesis has been
around since the nineteenth century. Though it virtually
disappeared from official scientific discussion by 1930, the
concept received its greatest clarity from the contributions
of engineer Ralph Juergens beginning in 1972. Juergens
proposed an electric Sun model, along with the corollary
that cometary comas and tails are produced by an electrical
exchange between the Sun and the comet. Later, in the early
80’s, physicist James McCanney set forth his own version of
the electric comet. He predicted that comets would be found
to emit X-rays.
Comet Linear had
more evidence to present. As the comet neared its perihelion
or closest approach to the Sun—about 114 million kilometers
(70 million miles) from the Sun, or three quarters of the
distance from the Sun to Earth—astronomer Mark Kidger was
observing Linear with the Jacobus Kapteyn Telescope at La
Palma in the Canary Islands. He noted something strange. The
normal teardrop shape of the coma was undergoing an
unexpected metamorphosis. Over several nights he watched the
comet elongate into a "cigar" shape. Kidger soon realized
that the nucleus of Linear was breaking apart—and
catastrophically. This was not merely a fragmentation of the
comet into separate visible pieces. The comet was dissolving
in front of his eyes.
“Comet LINEAR
seems to be dissolving into an amorphous haze of gas and
dust”, exclaimed a NASA Express Science News release. “The
break-up of Comet Linear as it swept past the sun last week
has shocked astronomers into rethinking theories of the
origins of such rocky ice balls”, reported Space.com on
August 4, 2000.
How did this
happen? A NASA release of July 31, 2000, reports that,
“Intense solar heating apparently triggered a massive
disruption of the comet's fragile icy core when it passed
close to the Sun”. Kidger suggested the same thing, invoking
“intense heating” and “thermal stresses” on the comet. But
it is not reasonable to assume that a mile-size ice chunk
would explode in space under something as mild as solar
radiation millions of miles from the Sun. As an icy body
sublimates in the Sun, it cannot even convey heat a few
inches into its interior. An explosion due to heating,
involving extreme forces deep within a body, is unthinkable.
Many comet
watchers began to consider seriously whether comets are
actually loosely aggregated collections of "mini-comets",
permitting them to fly apart when disturbed. Some began to
speak of Linear as an aggregation of cosmic fluff—a “wimpy
fluff ball”, as astronomer Donald Yeomans put it.
But prior
picture of the comets Halley and Borrelly—and most recently
of comet
Wild 2—make clear that comet nuclei are solid
objects. It was the Stardust mission to Wild 2 that produced
the best pictures ever of a comet nucleus. It showed a
well-defined and cratered surface with no indications of
separate objects held in a flimsy aggregation.
More details on
comet nuclei will be forthcoming soon, when the
Deep
Impact mission fires a 370 kilogram copper
projectile into the nucleus of Comet Tempel 1. The event is
scheduled for July 4.
In the electric
model of comets, there is nothing unexpected in an explosive
demise. As a comet moves through the radial electric field
of the Sun, approaching perihelion, the nucleus suffers the
maximum electrical stress. This usually results in an
increase in brightness of the nucleus due to a larger number
of cathode arcs operating simultaneously, explosively
removing solid material from the nucleus and accelerating it
into space to form the dust tail. Both of these conditions
were noted in the case of Comet Linear, suggesting that the
comet was progressing toward an internal discharge.
A comet nucleus
can be compared to the insulating material in a capacitor.
As charge is exchanged from the comet’s surface to the solar
wind, electrical energy is stored in the nucleus in the form
of charge polarization. This can easily build up intense
mechanical stress in the comet nucleus, which may be
released catastrophically, as in a capacitor when its
insulation suffers rapid breakdown. The comet will explode!
As suggested by
electrical theorist Wallace Thornhill, “comets break up not
because they are chunks of ice ‘warming’ in the Sun, and not
because they are aggregations of smaller bodies, but because
of electrical discharge within the nucleus itself”.
There were more
surprises. Perhaps the greatest shock came from analysis of
the debris left by the comet’s dissolution. According to Hal
Weaver, an astronomer at Johns Hopkins University in
Baltimore (as reported in an AP story on May 18, 2001),
researchers were “surprised at the ratio of ice to dust and
rock in Linear”. Analysis showed that Linear “had about 100
times more solid rock and dust than ice”.
But the problem
of missing water on the nucleus of comets is as old as the
Giotto probe of Comet Halley, which could not find any
definitive evidence of water but did find evidence
against the presence of water. No water could be found
on the nucleus of comet Borrelly. When comet
Shoemaker-Levy 9 broke apart, astronomers
reasoned that the fractured nucleus would expose fresh ices
that would sublimate furiously. So several ground-based
telescopes and the Hubble Space Telescope trained their
spectroscopes on the tails of the fragments of SL-9, looking
for traces of volatile gases. None of the gases was found.
Events and
observations surrounding the breakup of Comet Linear thus
offer many pointers to the true electrical nature of
cometary intruders. Comets may or may not possess volatiles,
and we can be confident that comets exhibit much more than
sublimating ices. Only electric discharge will account for
the full range of new data on comets.
_______________________
Please check out Professor Don Scott's
new book The Electric Sky.
NOTE TO
READERS: Wallace Thornhill, David Talbott, and Anthony
Peratt will share the stage with other investigators of
planetary catastrophe at the British Society for
Interdisciplinary Studies “Conference 2007” August
31-September 2.
GET INFO