Transcript Pluto - Hofstra

The “Not-Quite-Planet” Pluto …and Friends!
Pluto’s Orbital Eccentricity
(Elliptical Orbit, ~30-50 AU from Sun)
How to Survive a Neptune-Crossing Orbit:
 A 3:2 Resonance between Neptune and Pluto
(& various other “Plutinos”!)
Pluto’s Orbital Inclination out of the Ecliptic Plane
Charon: Ferryman of the dead
over the River Styx, into Hades…
The Five (currently) known Moons of Pluto…!
Pluto is Not as Big as we first thought!
Pluto is Cold! (=< 40 K ~ -387o F!)
Gorgeous Pluto! The dwarf planet has sent a love note back to Earth via our New Horizons spacecraft, which has traveled
more than 9 years and 3+ billion miles. This is the last and most detailed image of Pluto sent to Earth before the moment
of closest approach, which was at 7:49 a.m. EDT Tuesday - about 7,750 miles above the surface -- roughly the same
distance from New York to Mumbai, India - making it the first-ever space mission to explore a world so far from Earth.
This stunning image of the dwarf planet was captured from New Horizons at about 4 p.m. EDT on July 13, 2015, about 16
hours before the moment of closest approach. The spacecraft was 476,000 miles (766,000 kilometers) from the surface.
Images from closest approach are expected to be released on Wednesday, July 15.
Image Credit: NASA
#nasa #pluto #plutoflyby #newhorizons#solarsystem #nasabeyond #science312k likes11.8k comments
Pluto’s Friends…
The “Kuiper” (or “Edgeworth-Kuiper”) Belt:
Hypothesized for decades after Pluto’s Discovery in 1930…
…not discovered until 1992 (“1992 QB1”) by David Jewitt & Jane Luu!
New Kuiper Belt Object (“K.B.O.”) discovered by Trujillo & Brown
in 2002: “Quaoar”! (…named after the Tongva creator god…)
Then in 1993, Brown, Trujillo,
& Rabinowitz discovered Sedna!
(…named after the Inuit goddess of the sea,
living at the bottom of the frigid Arctic Ocean…)
 Because Sedna then became
“the coldest most distant place
known in the Solar System”!
Q: Why is Pluto no longer defined as a “Planet”?
The Currently Official
Definition of a Planet:
(…after many different ideas
proposed, criticized, & rejected!)
But this condition
can be ambiguous;
why even bother with it…?
(…what’s the key motivation for
deliberately demoting Pluto?)
Pluto Demotion Vote
by the International
Astronomical Union (IAU)
on August 24, 2006!
 If Pluto Stays a “Planet”, then How Many More Solar System Objects
will have to Become “Planets”? (esp. Newly-Discovered Objects!)
The “final straw” for Pluto’s Planet Status: Eris Discovered in Jan. 2005!
Eris: Was the first known Kuiper Belt Object Larger than Pluto!
Time for a
Planetary
Comeback…?
Until: The New Horizons mission images in July 2015 upgraded
Pluto’s diameter to 2,370 km… 34 km Bigger than Eris!
IAU (Mythological) Naming:
Eris: Greek Goddess of
Chaos, Strife, & Discord!
(and daughter of Nyx)
(…and Eris’ moon…):
Dysnomia: Eris’ daughtEr,
Greek goddess of Lawlessness!
Provisional Naming: Eris & Dysnomia were first
(unofficially) known as “Xena” & “Gabrielle”…
Should we have kept Pluto a “Planet” out of Historical Tradition?
Counting the Planets… According to History…
In Antiquity:
(Geocentric
Universe!)
Copernicus (1543): Herschel (1781):
(Heliocentric
Solar System)
1) Sun
1) Mercury
1) Mercury
2) Venus
1) Mercury
2) Moon
2) Venus
2) Venus
3) Earth
2) Venus
3) Mercury
3) Earth
3) Earth
4) Mars
3) Earth
4) Venus
4) Mars
4) Mars
5) Ceres
5) Mars
5) Jupiter
5) Jupiter
6) Jupiter
6) Saturn
6) Saturn
7) Saturn
________
7) Uranus
9) Jupiter
7) Uranus
________
10) Saturn
8) Neptune
11) Uranus
________
________
7
6
7
Piazzi (1801):
(Asteroids!)
1) Mercury
6) Pallas
7) Juno
8) Vesta
Adams &
LeVerrier
(1846):
4) Mars
5) Jupiter
6) Saturn
________
11
8
Counting the Planets According to History (continued…)
Adams &
LeVerrier
(1846):
1) Mercury
2) Venus
3) Earth
4) Mars
5) Jupiter
6) Saturn
7) Uranus
8) Neptune
________
8
Tombaugh
(1930):
IAU
(8/16/2006):
IAU
(8/24/2006):
1) Mercury
1) Mercury
2) Venus
3) Earth
4) Mars
5) Ceres
6) Jupiter
7) Saturn
8) Uranus
9) Neptune
10) Pluto &
11) Charon
12) Eris…
________
1) Mercury
2) Venus
3) Earth
4) Mars
5) Jupiter
6) Saturn
7) Uranus
8) Neptune
9) Pluto
________
9
12+
2) Venus
3) Earth
4) Mars
5) Jupiter
6) Saturn
7) Uranus
8) Neptune
Pluto
________
8
“Even though I lost Eris
as the tenth planet,
I suddenly realized
that I had an opportunity
to actually make a
scientific definition of the
word ‘planet’ that
described the
solar system correctly.”
-- Mike Brown,
co-Discoverer
Of Eris
The dwarf planet Pluto is
recognised as an important
prototype of a new class of
Trans-Neptunian Objects...
“plutoids”
-- IAU, 6/11/2008