Is Pluto a Planet?

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

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

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

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!

What makes a planet?

• It goes around a star.

Io and the Moon are not planets

because they don’t go around a star.



• It does not generate heat internally.

Jupiter is a planet.

since it is not heated by nuclear reactions.



• 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.



• 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

..and a member of the Kuiper Belt

Pluto

Pluto could have dual status.1000 Piazzi2000 Herschel3000 Leonardo4000 Hipparcus5000 IAU6000 United Nations7000 Curie8000 Isaac Newton9000 HAL10000 Pluto?

ATC Clapometer

Clap Cheer

Standby Mode: Quiet Please

Clap for Yes, Pluto is a Planet

Cheer for No, Pluto is NOT a planet

Yes No



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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

Documents

Is Pluto a Planet?