Planets Redefined

1
Planets Redefined
What the heck happened to Pluto!!!!
2
Planets the old definition.

• Originated by the Ancient Greek work Planetai
• Referred to the seven wanderers. Objects that
  were not fixed to the celestial sphere.
• Remember the names of those wonderers?
  ___________________

3
Finding the Planets

• Planetai includes Sun and Moon.. Which are not
  planets.
• Uranus was added by William Herschel in 1781 by
  using a telescope.
• Neptune was first observed by Galle and d'Arrest
  on 1846 though first observed by Galileo when
  observing Jupiter.

4
Finding the Planets Continued

• Ceres was discovered in 1801 by Giuseppe Piazzi
  and was classified as a planet for half a century
  before it lost its status as a planet.
• Pluto was finally added in 1930 by Clyde W.
  Tombaugh at Lowell Observatory in Arizona.

5
All is good

• Since the 1930s it has been widely accepted that
  there were nine planets.
• 1990 began to change this popular line of
  thinking.
• Technology like the Hubble Space Telescope,
  computer imagining, and more numerous and
  advanced telescopes began to detect objects on
  the outer fringe of the solar system.

6
Lets blame Mike Brown

• In 2003 Caltech astronomer discovers an object
  (later called Sedna) in what is called the Oort
  cloud.
• Sedna was larger then a comet yet smaller then
  Pluto.
• Oort cloud a cloud of icy debris that surrounds
  the solar system
• Kuiper Belt a denser area of icy material
  within the Oort Cloud where large chunks of ice
  can be found (like comets, and.. Pluto!)

7
Oort Cloud
8
Lets blame Mike Brown(cont.)

• During the late 1900s and Early 2000s several
  other trans-Neptunian objects were found. None
  larger then Pluto!
• Mike did it again later in 2003, this time what
  he would find would rock the scientific
  community
• A trans-Neptunian object located in the Kuiper
  Belt that was larger then Pluto.
• And it had a moon!!!!!!!!

9
Trans-Neptunian Objects
10
Too Much For Astronomers

• Many astronomers were already expressing that
  Pluto was not a planet.
• Now this new object (later named Eris) was too
  much. It was too small, it had a very odd orbit,
  and it did not lie on a flat plane as the other
  planets (like Pluto)
• Problem is there was never a scientific
  definition for Planet!!!

11
Eris the goddess of Strife and discord.
12
August 24, 2006

• A meeting of the IAU (International Astronomers
  Union) finally agreed on the definition of a
  planet.

13
Definition of a Planet

• A planet in the solar system is a celestial body
  that

14
Definition of a planet

• 1. Is in orbit around the sun.

15
Definition of a Planet

• 2. has sufficient mass so that it assumes a
  hydrostatic equilibrium (nearly round) shape.
• In other words, the gravity is so great in all
  directions, the only shape it can be is round.

16
Definition of a Planet

• 3. And, has "cleared the neighborhood" around its
  orbit.
• Here is the catch There should be no space
  debris in its orbit.
• This part of the definition is what ruled out
  Eris as a Planet, and expelled Pluto from the
  definition.

17
The New (old) Planets
18
So what do we do with Pluto?

• It is now classified as a Dwarf Planet along
  with Eris and Ceres (the asteroid).

19
What is a Dwarf Planet?

• A dwarf planet is a planet in our solar system
  that.

20
Definition of Dwarf Planet

• 1. Is in orbit around the sun

21
Definition of Dwarf Planet

• 2. has sufficient mass for its self-gravity to
  overcome rigid body forces so that it assumes a
  hydrostatic equilibrium (nearly round) shape

22
Definition of Dwarf Planet

• 3. has not cleared the neighborhood around its
  orbit.

23
Definition of Dwarf Planet

• 4. is not a satellite (in other words, it is not
  a moon of another planet).

24
12 Dwarfs Where is Snow White?
Above are 12 more objects that may be classified
as Dwarf Planets soon.
25
Houston We Have a Problem.

• Hold on Mr. Lee may have to rewrite this power
  point in the near future!
• Scientist are not all in agreement with this new
  definition of Planet

26
Is Earth A Planet?

• There are about 1000 known asteroids in the
  Earths Orbit (called NEAs or Near Earth
  Asteroids).
• Some as large as 32 miles across!
• By definition, the Earth is not a planet either,
  because it has not cleared it path around the
  sun!

27
Jupiter is even worse

• Jupiter travels through 100,000 Trojan and Greek
  asteroids as it travels around the sun!
• Mars does as well.

28
Lets get rid of Neptune too!

• Though Neptune has only 4 KNOWN Trojan asteroids
• Keep in mind that about every 75 years Pluto
  crosses the path of Neptune to be closer to the
  sun for about 20 years.
• Although they can not collide, there is a
  gravitational attraction between the two, so
  Neptune has not cleared its path because of Pluto!

29
So what would make me happy?

• On a personal note!
• Throw out the part about clearing it path.
• They are all planets but there are three types
• Terrestrial, Jovian, and Dwarf.

30
Why Express My Opinion?

• Discovery is important.
• A probe to Pluto was sent January 2006. It
  should arrive in 2015. Was already having
  financial support problems, would have gone under
  if definition happened earlier.
• Why study invest in the outer solar system if
  there is nothing exciting to find out there?!?

31
More Information can be found at..

• All images and facts were aquired from the
  following sites
• http//en.wikipedia.org
• http//www.nineplanets.org/