boatingonthehudson.com HOLIDAY 2013 53
crevasses, fractures, and fissures
as this occurs. As a side note, the
famous comet Halley is believed
to have undergone such an un-
expected eruption years after it’s
1986 approach to the sun. As it
receded from the sun and became
fainter and fainter, astronomers
often observed it to calibrate their
instruments and one time in the
early 1990’s saw it increase signif-
icantly in brightness! One theory
being that it was either hit by an
object, or some form of eruption
or “burp” occurred in it’s nucleus.
As of this writing some as-
tronomers are still of the opinion
that ISON is not going to become
anything like it was hyped up to
be, as the comet is two magni-
tudes fainter than it was predicted
to be at this point in its approach.
However, there is some really
good news for the majority of us
who believe (know) that ISON is
going to be a great comet!
First of all, as the comet
has gotten closer to the sun, ongo-
ing and increasing observations
of it have become more accu-
rate. A comets nucleus rotates
as it approaches the sun, and
astronomers have been able to
determine the rotational aspects
of ISON’s nucleus by observing a
jet of material sublimating from
its surface. It is theorized that
depending upon how it is rotating
and in what direction, that this
significantly affects the growth
and appearance of a tail, as the
warmth increases over the entire
surface area of the nucleus allow-
ing more material to be sublimat-
ed. According to astronomers at
the Lowell observatory, it appears
that ISON has been rotating in a
fashion that will allow only half of
its nucleus to undergo significant
sublimation until about one week
prior to its closest approach to the
sun! As the comet gets closer to
the sun and increases its speed,
it is predicted to begin to rotate
faster and faster and in other
directions as well! This is virtually
guaranteed to produce a mag-
nificent tail or a surge of activity
around November 20th as ISON
is believed to be a pristine comet
that originated from deep within
the Oort cloud and contains lots
of material to sublimate.
Even better news, and
contrary to many doomsayers,
new measurements of the size of
comet ISON’s nucleus has shown
that it is large enough to exceed
the so called “shred limit” size of
approximately 200 meters for a
sun grazer comet when it ap-
proaches the sun. ISON’s revised
diameter of almost 2 kilometers
is large enough to easily allow it
to survive it’s close graze around
the sun when it is at it’s perihelion
distance of only approximately
680,000 miles on November 28,
2013.
Beginning at the end
of November and through the
January - February 2014 time-
frame, Comet ISON should be
easily visible in our skies, and as
a possible added treat, some are
predicting a new meteor shower
for January when the earth passes
through some of ISON’s cometary
debris. For those who are plan-
ning to observe the comet and
possible meteor shower in the
coming months it is important to
remember that you do not neces-
sarily need a telescope to do so.
Binoculars and your naked eyes
are actually the best instruments
of all to view such spectacular
sights. However, good planning
is essential to ensure the best
observing experience. Remember
that comets do not go “whoosh”
in the sky like meteors, and they
remain visible for months at a
time, but are constantly chang-
ing positions as they orbit the sun
and fly by the earth. Be sure and
consult astronomical sources of
information on the internet and in
magazines for the most accurate
positions and what to expect to
see. There are numerous sources
of information specifically relat-
ing to comet ISON already on the
internet and are updated daily.
Some of the best are:
gov,
and
Sky and Telescope and Astronomy
Magazine that have some easily
referenced locator charts for the
coming months.
By November, the comet
should have achieved naked eye
visibility and be visible in the
early morning sky near the planet
Mars and star Regulus in the
constellation Leo. But, it is wise to
remember, that even though many
astronomers, scientists, skywatch-
ers, (including myself), and other
eternal celestial optimists have
virtually assured us that the ap-
pearance of comet ISON will be
one of the most spectacular celes-
tial events in recorded history, like
all things in the universe, Mother
Nature will always have the
last say so, and She will always
reserve the right to change Her
mind. Lets hope She gives us all a
well needed holiday treat!
Wishing you all a Merry Christ-
mas and Safe, Happy, Healthy,
Holiday Season and Prosperous
New Year 2014!
Clear Skies,
Ed and Sue
Astronomy Delight! In Hyde Park,
N.Y. welcomes your questions
and comments regarding this
column and offers day and night
after-school enrichment programs,
classroom events, scouts, camps,
group lectures, individual as-
tronomy programs, and observa-
tion courses for families, parents,
and children of all ages through-
out the Tri-state area and upstate
NY FRANCHISE INQUIRYS ARE
WELCOME (845) 229-4434 www.
Astronomydelight.com
HOLIDAY 2013.indd 60
11/7/13 7:50 AM
