This presentation was made for elective course in ESL for topic Astronomy, Pluto.

1. THE HISTORY OF
PLUTO
How it all happened…

2. PLUTO
Pluto, formal designation 134340 Pluto, is
the second-most-massive known dwarf
planet in the Solar System (after Eris) and
the tenth-most-massive body observed
directly orbiting the Sun. Originally classified
as the ninth planet from the Sun, Pluto was
recategorized as a dwarf
planet and plutoid due to the discovery that it
is only one of several large bodies within
the Kuiper belt.

3. Before 1930 (when Pluto was discovered)
there were only 8 planets known. But the
great astronomer Percival Lowell was
absolutely convinced that somewhere
beyond Neptune there was an
undiscovered ninth planet, dubbed Planet
X.

4. Lowell was sure that the Planet X would
be a massive gasball (because it
influenced the orbits of Uranus and
Neptune). Unfortunately, he died in 1916
exhausted by his search. In 1930 a young
man Clyde Tombaugh spotted Pluto. He
saw that the new planet was nothing like
the massive gasball. But it was the first
American-discovered planet, and no one
was going to be distracted by the thought
that it was really just a distant icy dot.

5. The distant, ice-covered world is no longer a true
planet, according to a new definition of the term
voted on by scientists in 2006.
"Whoa! Pluto's dead," said astronomer
Mike Brown, of the California Institute of
Technology in Pasadena, as he watched a
Webcast of the vote. "There are finally,
officially, eight planets in the solar system."

6. Pluto is no longer a planet

7. What is a planet today?
According to the new definition, a full-
fledged planet is an object that orbits the
sun and is large enough to have become
round due to the force of its own gravity. In
addition, a planet has to dominate the
neighborhood around its orbit.

8. Pluto has been demoted because it
does not dominate its neighborhood.
Charon, its large "moon," is only about
half the size of Pluto, while all the true
planets are far larger than their moons.

9. Unique image taken by Hubble telescope where Pluto and its
moon Charon are seen.

10. On September 13, 2006, the IAU
(International Astronomical Union)
included Pluto in their Minor Planet
Catalogue, giving it the official minor
planet designation.

11. REACTION
Reception to the IAU decision was mixed.
While some accepted the reclassification,
others seek to overturn the decision with
online petitions urging the IAU to consider
reinstatement.
Some members of the public have also
rejected the change, citing the disagreement
within the scientific community on the issue,
or for sentimental reasons, maintaining that
they have always known Pluto as a planet
and will continue to do so regardless of the
IAU decision.

13. CREDITS:
This presentation was made with the help
of:
 Wikipedia the Free Encyclopedia
 news.nationalgeographic.com
Pluto not a planet, Astronomers rule by
Mason Inman
 Bill Bryson A short history of nearly
everything