|Why isn't Pluto a planet anymore?
|Question Date: 2007-03-30|
The reason why there was debate over whether Pluto
constitutes a planet or not is due to the fact
that in previous times, there wasn't a good
definition to what a "planet" was. Scientists
just found 9 of these objects that were large
enough to see through telescopes that orbit our
sun. And frequently the smaller things that we
couldn't see we would call "asteroids" or
something like that (much like the asteroid belt
in our solar system). However, with the advent of
better telescopes, we noticed that there were lots
of things that were bigger than Pluto that orbited
our sun as well. So instead of adding lots of new
planets, scientists finally decided to define what
"planet" was. The definition that scientists
settled on is any object that has sufficient
gravity to make it round-ish, orbits the sun, and
has cleared its specific orbit of smaller objects
(which Pluto has not done).
Pluto is not considered a planet anymore
because The International Astronomical Union (IAU)
voted on their first official definition of a
planet, and this definition does not fit for
Pluto. Scientists recognized that Pluto was really
one of many dwarf planets from the Kuiper Belt.In
terms of its or composition and its orbit, Pluto
is unlike the other planets. There is still some
controversy and disagreement amongst astronomers
about the new definition of a "planet". We will
have to wait and see whether the new definition
"sticks" or not. For now, there are three official
classes of objects in our Solar System: planets,
dwarf planets, and small solar system bodies.
Planets include the eight traditional planets from
Mercury to Neptune, but no longer Pluto. Pluto is
joined amongst the dwarf planets.
want to know more about Pluto, please go to the
Hope it helps!
I will admit I was a little surprised when
Pluto was reclassified--my bike was named Pluto!
But I think it's the right thing. It's better to
describe things the way they are than the way we
thought they were.
That's the fundamental
thing about science:
Scientists have to be
willing to admit when they were wrong, so that our
understanding of the universe can
Here's what Bill Nye the Science
Guy has to
a poem my friend wrote about the
favorite sphere they did remove
From line after
the water god.
The IAU did not approve
only orb named for a dog.
Click Here to return to the search form.
Copyright © 2020 The Regents of the University of California,
All Rights Reserved.