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Is Pluto a Planet?
Dr John K. Davies
&
Dr Suzie Ramsay Howat
UK Astronomy Technology Centre,
Royal Observatory, Edinburgh, Scotland
The classical solar system
Planet Uranus imaged from Voyager 2.
Planet Neptune from Voyager 2.
Percival Lowell
Lowell’s Tomb, shaped like Planet Saturn
Clyde Tombaugh and
the Pluto Telescope.
Discovery of Pluto, 1930
Orbits of Pluto and Neptune.
Nucleus of Halley’s Comet
Pluto is Shrinking
Pluto is covered with ice.
Pluto and Charon (Gemini Observatory)
Pluto should have vanished by now!
Mercury and Venus: Planets without Moons
9064 Johndavies. A minor planet
• Discovered 1993
• Status: Main belt
asteroid
• Diameter: about 6km
• Brightness: V=17-18
• Composition: Rocky
• Dist from Sun 2.1-2.7
AU
243 Ida and Dactyl
Ida: Size about 56 km long. Dactyl: Size about 1.5 km.
45 Eugenia and its moon.
Eugenia size ~215km Satellite size ~13 km
Period ~4.7 days
Eugenia, The Movie
Pluto has an atmosphere
Pluto Express Mission. 2020?
Comets in the Oort Cloud
Comet Hale-Bopp
Interstellar comet (never seen)
Long Period Comet,
like Hale-Bopp
Short Period Comet.
Comet Orbits
Gerard Kuiper 1905-1973
Kenneth Edgeworth. 1880-1973
Jane Luu and Dave Jewitt
University of Hawaii 2.2m Telescope
Discovery of 1992 QB1
The Classical Kuiper Belt
The Plutinos
1998 WW31 a Kuiper Belt Object with a satellite
Some of the the largest known Kuiper Belt
Objects
Stop Press – ‘Sedna’
Sedna: EKO or Oort Cloud Object?
Sedna. Planet10?
Orbital Elements and Stable Regions
Comet Ring as predicted by Fred Whipple in 1964,
virtually what we today call the Kuiper Belt
According to ‘First Steps to Astronomy and Geography’,
Hatchard & Son, London, 1828 there are 11 planets.
Mercury, Venus, Earth, Mars, Vesta, Juno, Ceres,
Pallas, Jupiter, Saturn and Herschel (Uranus)
Sun
Ceres
Venus
Pallas
Earth
Juno
Mars
Vesta
But 4 of these are no longer in
lists of planets published today
Tradition in Astronomy
Constellations
Lunar Sea!
What makes a planet?
• It goes around a star.
Io and the Moon are not planets
because they don’t go around a star.
What makes a planet?
• It goes around a star.
• It does not generate heat internally.
Jupiter is a planet.
since it is not heated by nuclear reactions.
What makes a planet?
• It goes around a star.
• It does not make heat by nuclear reactions.
• It is spherical.
So MOST asteroids are not planets
since they have not collapsed to spherical shapes.
What makes a planet?
• It goes around a star.
• It does not make heat by nuclear reactions
• It is (more-or-less) spherical.
• It is bigger than 1000km in diameter
Is Pluto a Planet?
Please raise hands for yes
Or not?
Please raise hands for NO
Pluto is a small icy planet
Like Neptune’s moon Triton
Pluto
..and a member of the Kuiper Belt
Pluto could have dual status.
1000 Piazzi
2000 Herschel
3000 Leonardo
4000 Hipparcus
5000 IAU
6000 United Nations
7000 Curie
8000 Isaac Newton
9000 HAL
10000 Pluto?
ATC Clapometer
Clap
Cheer
Standby Mode: Quiet Please
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Clap for Yes, Pluto is a Planet
Yes
No
Cheer for No, Pluto is NOT a planet
Thanks very
much!
Bye for now,
Drive safely.
Is Pluto a Planet?
• Presented by: John Davies and Suzie Ramsay Howat.
• Written by: John Davies
• Thanks to: Jason Cowan, Chad Trujillo, Lowell
Observatory archives , NASA, Yerkes Observatory, Dave
Jewitt, Jane Luu, Martin Duncan and John Spencer
For more information.
Published by CUP, get it from Amazon.
Mutual Eclipses of Pluto and Charon