Download Pluto Evidence

Name: ___________________________________
Date: ______________
Per._________
Pluto Evidence
Model A: Pluto is a planet
Evidence 1:
Model B: Pluto is not a planet
Supports Model _____________
Pluto should be called a planet for cultural and historical
reasons. We have been calling it a planet for decades, and this
means that it is a planet. When something has been called a
planet for many, many years, it would be wrong to suddenly say
that it is not a planet any more.
Evidence 2:
Supports Model _____________
Years ago, my astronomy professor told me a planet has two
properties.
First, a planet is a non-self-luminous round object. A self-luminous
object is an object that produces its own light, like the sun. So a
non-self-luminous object is an object like the earth that does not
produce light. Pluto is a non-self-luminous object.
Second, a planet is an object that orbits a star. Pluto orbits the sun, which is a star.
Therefore, Pluto is a planet.
Evidence 3:
Supports Model _____________
Pluto is not a planet because it has not cleared out its local neighborhood. When a
planet has cleared its local neighborhood, there are no other objects flying where it
orbits. Any object that passes near the planet either gets
pulled into the planet or gets flung away by the planet.
Because the planet’s gravity is so strong, it either pulls in
small objects (causing the planet itself to get larger) or it
slingshots the smaller object away, sending it far away.
That is why big planets in our Solar System do not have anything near them except for
moons. Pluto does not meet the important criteria of clearing its neighborhood and
therefore is not a planet. There are lots of objects that pass by Pluto’s orbit. Lots of
objects in the Kuiper Belt pass near Pluto. Pluto’s gravity is not strong enough either to
pull these objects in or fling them away.
Evidence 4:
Supports Model _____________
Re-naming Pluto to a dwarf planet is a very bad decision that makes people less
interested in astronomy. Now everyone is disappointed with scientists, because people
feel cheated that Pluto is not a planet anymore. Adding new planets would excite the
public. Taking planets away is bad for science.
Evidence 5:
Supports Model _____________
The new definition says that Pluto is not a planet
because it has not cleared its neighborhood of
smaller objects (except moons). In other words,
there are many smaller objects that move around
in the same area as Pluto.
But there are at least three other planets that
have not cleared their neighborhoods of smaller objects.
Saturn has rings made of many, many small objects. Saturn has not cleared these out
of its orbit yet.
Jupiter also has rings. Jupiter has thus not
cleared its orbit.
Pluto regularly crosses Neptune’s orbit.
Therefore, Neptune has not cleared its
orbit, either.
But it makes no sense to say that Jupiter,
Saturn, and Neptune are not planets! So
we should allow Pluto to be a planet, too.
Evidence 6:
Supports Model _____________
The demotion of Pluto was done in a political way, not a scientific way. The definition
adopted was done so on the last day of the IAU's two-week conference by 4% of its
members, most of whom are astronomers who do not specialize in planets. No
electronic voting was allowed, so the 96% of IAU members not present in the room had
no vote. Immediately after the vote to classify
Pluto as a “dwarf planet,” over 300 professional
astronomers signed a petition saying they will not
use the new definition. The vote to classify Pluto
as a dwarf planet was not a legitimate vote. Pluto
is still a planet.
Evidence 7:
Supports Model _____________
They say that Pluto is a dwarf planet, not a planet. But saying that a
dwarf planet is not a planet is silly. It is like saying that a grizzly bear is
not a bear. Pluto is a planet.
Evidence 8:
Supports Model _____________
Pluto is composed mostly of frozen nitrogen. If Pluto were orbiting near the sun, it would
quickly vaporize. There would be nothing left! The other small planets (Mercury, Venus,
Earth, Mars) are rocky. They would not be vaporized by the sun, even if they orbited
close to the sun. (And Mercury does orbit close to the
sun.)
Comets are also made of substances that are vaporized
by the sun. Pluto is more like comets than planets. Pluto
should not be counted as a planet.