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2022-08-26
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****************************
* *
* - THE COMET COMETH - *
* *
* Halley's Solar Sojourn *
* *
* by Greg Malone *
* *
****************************
This month we take a look at Comet
Halley's travels through our solar
system over the last 76 years since
the last visit in 1910. We will also
make a close examination of the
relationship of Halley's orbit and the
orbit of the Earth during this visit.
Around the Sun in 76 Years
--------------------------
If you will select the sojourn menu
option titled 'Around the Sun in 76
Years', you will observe the
elliptical path of Comet Halley
through the solar system during the
last 76 years. Halley's orbit is seen
in relationship to the orbits of the
other major planets.
An examination of the dates along
Halley's path will reveal that the
comet was travelling very fast as it
made its retreat away from the Sun. By
1915, only 5 years after swinging
around the Sun, Halley was already
midway between the orbits of Saturn
and Uranus. However, Halley can be
seen to decelerate rapidly inasmuch
as it took another 33 years for it to
reach aphelion, its farthest point
away from the Sun. As the comet made
the turn at aphelion in 1948, it
began to pick up speed again, due to
the gravitational pull of the Sun.
In another 32 years, Halley would be
making the fast solar flyby again in
1986.
Concerning Fast Snowballs
-------------------------
A comet's speed is always at its
maximum when it is close to the Sun.
This becomes evident if you'll
consider that in late 1985 Halley is
out near the orbit of Mars, just
becoming visible to the naked eye on
Earth. And yet, just a few months
later in February of 1986, Halley is
making its swing aroung the Sun and a
few months after that it has already
zipped past the Earth and become
invisible to the naked eye again!
One fast snowball! What an edge you'd
have in a snowball fight with one of
those buggers!
Close Encounters
----------------
The 'Close Encounters' option in
the menu will provide you with an
animated display of the relative
orbits of Comet Halley and the Earth.
Use the function keys (f1 and f7) to
step forward and backward in time.
The dates displayed include the time
between September 10 of 1985 and May
24, 1986, approximately 8 1/2 months.
Time progresses in roughly 2 week
increments with each step.
How to be in the Wrong Place at the
Worst Time
----------
From this display we learn that the
Earth will actually experience 2
flybys of the comet. The first, in
early December of 1985, and the
second, and closest, in early April
of 1986. Neither of these flybys,
however, will occur at the time when
Halley will be at its brightest,
early in February, 1986. Notice that
when Halley is closest to the Sun,
and therefore at its brightest, the
Earth will be on the exact opposite
side of the Sun, missing the
celestial light show during its full
glory!
The Show Must Go On!
--------------------
This is not to say that we won't
still have a nice showing of the
comet. Armed with a pair of
binoculars and/or a 35mm camera, we
will still be able to see Halley on
its way out back into the cold depths
of the solar system. We encourage you
to follow the comet as it makes its
solar sojourn. Such an experience,
when understood, should give us all a
fresh perspective regarding ourselves
and our place in this universe.
Send Us Those Photos!
---------------------
We will be making and collecting
amateur photos of Comet Halley and
running digitized reproductions of the
best ones in the months during and
following Halley's visit. If you have
access to a 35mm camera, take several
pictures of the comet, using brief
time exposures of 30 seconds to a
minute or two. If you get one or two
that you're especially proud of, send
us duplicate prints. We will share
your treasures with the other
readers.
Notice: All pictures and prints
sent to Loadstar become the property
of Loadstar. No photos will be
returned.
*** Happy Comet Hunting! ***
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