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Mr. Reynes' Fun
Science |
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Hooray
for Pluto!
Have
you ever read The Search for Delicious by Natalie
Babbitt? Long ago in a place far away, DeCree, the
Prime Minister was working on a new dictionary.
Everything was going well until he got to the D’s.
“Delicious is fried fish,” he wrote. “No,” said the
queen. “Delicious is a Christmas pudding.” “Nonsense,”
said the king. “Everyone knows that the most delicious
thing is an apple.” Soon the entire kingdom was in an
uproar. Everyone had a different definition for
delicious, and the kingdom was on the verge of civil
war.
Astronomers have been arguing over the definition for
the word “planet.” Recently, the International
Astronomical Union (IAU), a group of astronomers
(scientists who study outer space) wrote their first
“official” definition for the word planet. And like
DeCree’s definition, their new definition has caused an
uproar. Unfortunately, according to the new definition,
Pluto is not considered a true planet. Pluto is now
classified as one of several “dwarf planets” that can be
found in the outer regions of our solar system.
The
thought of Pluto being demoted to a “Dwarf Planet” has
upset a great many people. People are buying tee shirts
and bumper stickers to show their support. One tee shirt
for sale on the Internet reads, “Pluto is a Planet!”
Another shirt urges, “Vote for Pluto!” Bumper stickers
exclaim, “Honk if Pluto is still a Planet.” It is
important to remember that nothing we do on Earth will
actually change Pluto. Pluto will always be cold, icy,
and distant.
I
would be the first to object if Grumpy was yanked from
Disney’s Snow White and the Seven Dwarfs and
replaced with Pluto, the dog. But science isn’t
filmmaking, and when confronted with new information,
scientists must change their ideas. Science is a
systematic process of understanding our world, and
scientific ideas change over time as new information is
obtained. While Pluto’s demotion may come as a surprise
to many, those who are interested in astronomy have been
thinking that Pluto really does not fit with the other
planets.
The
word planet comes from the Greek. It means “wanderer.”
While stars keep their relative positions in the sky,
planets do not. They appear to move or wander among the
stars. When Pluto was discovered on February 18, 1930,
Clyde W Tombaugh was comparing photographs of the stars
that were taken one to two weeks apart. He was looking
for anything that might have shifted against the
background of stars. Sure enough, he found a wanderer,
a planet. Pluto!
Since
Pluto’s discovery more than 75 years ago, astronomers
have learned a great deal about our solar system. Here
are a few reasons not to include Pluto in the list of
planets:
-
In
the 1990s, a number of large asteroids were found in
the same region of the solar system.
-
Pluto is very small. It is about half the size of
our own moon. In fact, seven moons in our solar
system are larger than Pluto.
-
The orbit (its path around the Sun) of Pluto is more
eccentric (think elliptical) than the other planets.
-
Pluto’s orbit is inclined to the plane of the solar
system. It does not line up with the Sun’s equator.
Even
though Pluto is no longer listed as a planet in our
Solar System, I am still a fan of the little guy. And I
am excited that so many people are talking about the
science.
See
you at school!
Fun
Facts
Pluto
is a really cool planet. In fact, it’s so cool, it’s
freezing. A warm day on Pluto is about 210o C
below zero!
Pluto
is nearly 6 billion miles from the sun. A spacecraft
called “New Horizons” was launched in January 2006. It
will reach Pluto in 2015.
If the
Sun were a ball with a diameter of 1 meter (39.37
inches), then Pluto would be about as big around as the
lead in your pencil and would be over 2-1/2 miles away.
Want to
Learn More about Pluto and Our Solar System?
On
the Web
If you
would like to learn more about our solar system, check
out these websites:
http://kids.nineplanets.org/
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Pluto
http://starchild.gsfc.nasa.gov/docs/StarChild/solar_system_level1/pluto.html
Chabot Space and
Science Center
10000
Skyline Blvd., Oakland, CA; 510-336-7300;
www.chabotspace.org
This
is a terrific place to learn about Pluto and astronomy. On Friday nights, visitors can look through
Center’s giant telescopes and talk with the Center staff
and other stargazers.
