13 July 1994
By Todd E. Van Hoosear
EAST LANSING, MI This weekend will host a long awaited day for astro-
nomers world-wide as the remnants of a shattered comet, back from a two-
year hiatus in other regions of the solar system, returns to the Jovian
giant that scientists presume was the cause of its original demise.
The comet Shoemaker-Levy 9 will begin colliding with Saturn this
Saturday, July 16. Scientists are hoping that this collision will shed
light on the habits and charateristics of comets, the composition and
distribution of Jupiter's atmosphere, and how a planet reacts to such an
impact.
It was just such an impact that many scientists believe wiped the
dinosaurs off the face of the Earth 65 million years ago.
It was just such an impact, although on a smaller scale, that likely
caused the 1908 destruction of over 800 square miles of forest land in
Siberia and reportedly enabled Europeans to read their newspapers
outside at midnight from the glow of the resulting fires.
An event similar to the Jupiter collision, which was evaluated in an
article in today's The State News (Michigan State University's student
newspaper) to be equivalent to "one Hiroshima-sized bomb detonated for
every living person" on this planet, would most likely end our tenure
on Earth were it to happen here. Fortunately denizens of Terra have
nothing to worry about: the comet is quite firmly in the gravitational
grasp of the gas-giant and Earth is sufficiently distant from the blast
(the closest we ever get to Jupiter is around 792 million miles).
Unfortunately, the first impact will begin at 3:45 p.m., a time that
places the collision out of direct sight from Earth-based observatories.
Scientists will have to wait approximately 15 minutes for the site to
come into direct view from the Earth. Fortunately the spacecraft
Galileo will be an intimate 143 million miles away from Jupiter, and
astronomers will have front-row seats for the event thanks to the
impressive array of imaging sensors that will be recording the event.
Other space probes, including Voyager 2, Ulysses and Clementine, will
also be witnessing the event and relaying information to the Earth.
Voyager 2, which is close to departing the solar system, will transmit
radiation data on the collision. And the Hubble Space Telescope will
also be pointing its newly renovated lens in Jupiter's direction.
Fortunately again, this time for the backyard astronomers, the
secondary collisions will begin around 10:54 p.m., a prime time to aim
the telescopes skyward. Although again the direct impact will not be
visible, the site of the impact should rotate into view 10 to 20
minutes later, and there is a slight chance that some visible changes
may be seen from the Earth. The attack on Jupiter will continue
through the week until 12:33 a.m. Friday, July 22, when the last
fragments are expected to reach the planet's atmosphere.
The remains of the comet, which were discovered on March 24, 1993--one
year after its initial destructive meeting with Jupiter's gravitational
forces--number in the twenties and range in size from mountains to
molehills and smaller.
Many eyes will be on the shock waves generated by the impact of these
fragments. These waves will reveal much about the interior of the
planet. Scientists hope to gather information on the chemical and
physical composition of the atmosphere, including the amount of water
around the planet and the location of Jupiter's liquid hydrogen
interior.
Just what other impact might this collision have in the scientific
community? If scientists don't find enough water in the atmosphere,
they may have to take another look at the leading hypothesis that the
solar system was formed from one single could of dust and gas, as that
hypothesis would predict higher levels of water that we have currently
found. The comet itself is under question; scientists are hoping that
the fragments will be big enough to have an impact on the planet.
But hopes are up for this event. I will be unable to look skyward that
first evening due to the wedding of my friend Mike Runge, but there
will be plenty of other eyes tuned to that portion of the sky, and I'm
sure we'll all hear something about this once-in-a-lifetime event.
Keep your necks in good shape!
- Todd
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- T o d d E. V a n H o o s e a r -
``''' vanhoose@lalaland.cl.msu.edu - vanhoose@msu.edu - vanhoose@roundtable.msu.edu
(._.) Michigan State University - East Lansing, MI USA
(_) Computer Laboratory - Department of Communication
`---' http://lalaland.cl.msu.edu/~vanhoose
"Words are, of course, the most powerful drug used by mankind." - Kipling
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~