Is Pluto a Planet?
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Transcript of Is Pluto a Planet?
Is Pluto a Planet?
Dr John K. Davies
UK Astronomy Technology Centre, Royal Observatory, Edinburgh, Scotland
Executive Summary
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
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
Pluto has an atmosphere
New Horizons Mission-Pluto Flyby, July 2015.
Comet Hale-Bopp
Comet Orbits
Long Period Comet,like Hale-Bopp
Short Period Comet.
Interstellar comet (never seen)
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
Orbital Elements and Stable Regions
Some of the the largest known Kuiper Belt Objects
Late 2000 Varuna Discovered
November 2003 Sedna Announced
Sedna: EKO or Oort Cloud Object?
Sedna. Planet10?
The Discoveries Continue
• June 2002. Quaour discovered.
• Late 2004. Orcus (2004 DW4) announced• July 2005. Ortiz et al announce ‘discovery’
of 2003 EL61
• July 2005. Brown et al announce, via press release, existence of 2003 UB313 amidst allegations of ‘hacking’ by Ortiz et al
2003 EL61
• Irregular, rocky object with a glazing of ice.
• Rotates every 4 hours.
• Has two satellites.
2003 UB313 aka ‘Xena’
2003 UB313 aka Xena
2003 UB313 aka ‘Xena’
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
IAU Committees 2003-5: First attempts at planet definition split
community almost equally so new panel formed.
2006: Committee Meets in Paris to draft proposal for
Prague IAU meeting in August
Sunday 13th: Draft IAU resolution sent to press. Allows 12 planets and potential for
many more.
3 New Planets
Lots of Potential New Planets
Thursday 17th: Draft proposal slammed by Div III dynamicists
Tuesday 22nd lunchtime: Further Modified Draft Presented
New proposal slammed even harder!
Tuesday 22nd 1800hr: Further modifications seem to be getting closer
to consensus
Wednesday 23rd
• More modifications and coffee break debates over whether a dwarf-planet is the same thing as a “dwarf planet”.
Wednesday 23rd
• More modifications and coffee break debates over whether a dwarf-planet is the same thing as a “dwarf planet”.
and….
• If a dwarf planet is a kind of planet or a whole different thing.
Thursday 24th : The final Countdown
• 5A. A Planet is round, goes around the Sun and dominates its local space. A dwarf planet is round, goes around the Sun, has not cleared its local space and is not a satellite. Everything else is a small solar-system body
• 5B Change Planet to Classical Planet
Thursday 24th: The final Countdown
• 6A Pluto is a dwarf planet by the above definition and is recognised as the prototype of a new class of trans-Neptunian Objects.
• 6B This class of dwarf planets will be called Plutonids
Thursday 24th: History is Made
• 5A. A Planet is round, goes around the Sun and dominates its local space.
Thursday 24th: History is Made
• 5A. A Planet is round, goes around the Sun and dominates its local space.
• 5B Change Planet to Classical Planet
Thursday 24th: History is Made
• 5A. A Planet is round, goes around the Sun and dominates its local space.
• 5B Change Planet to Classical Planet
• 6A Pluto is a “dwarf planet” and the prototype of a new class of TNO’s
Thursday 24th: History is Made
• 5A. A Planet is round, goes around the Sun and dominates its local space.
• 5B Change Planet to Classical Planet
• 6A Pluto is a “dwarf planet” and the prototype of a new class of TNO’s
• 6B This class of dwarf planets will be called Plutonoids
Mike Brown’s Reaction
Some Other Astronomer Reactions
The People’s Reaction
The Astrologer Reaction.
• “Scorpio’s can be extremely explosive, and very direct, and this may be the trigger that makes them explode”
Milton Black, Australian Astrologer
• “This is a moment I’ve been waiting for, people are finally talking about Charon”
Eric Francis , Minor Planet Astrologer
Pluto is a small icy dwarf planet
Like Neptune’s moon Triton
..and a member of the Kuiper Belt
Pluto
Is Pluto a Planet?What do you think?
Clap for Yes, Pluto is a Planet
Cheer for No, Pluto is NOT a planet
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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
Comet Ring as predicted by Fred Whipple in 1964, virtually what we today call the Kuiper Belt
But 4 of these are no longer in lists of planets published today
Ceres
Vesta
Pallas
Juno
Sun
Venus
Earth
Mars
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)
Tradition in Astronomy
Constellations Lunar Sea!