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Halfway Around the World for 5 Minutes of data . Learning about the atmosphere of Pluto. Jeff Regester Greensboro Day School. Outline. History of Pluto and Outer Solar System science Occultations New Horizons . Pluto’s Discovery. Discovered by accident, on purpose

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Halfway around the world for 5 minutes of data

Halfway Around the World for 5 Minutes of data

Learning about the atmosphere of Pluto

Jeff RegesterGreensboro Day School


Outline
Outline

  • History of Pluto and Outer Solar System science

  • Occultations

  • New Horizons


Pluto s discovery
Pluto’s Discovery

Discovered by accident, on purpose

by Clyde Tombaugh, Lowell Observatory, 1930




Moons
Moons

Charon, discovered in 1978

by Jim Christie, USNO

 MPluto = MMercury/20


Moons1
Moons

Nix and Hydra, discovered in 2005 by Alan Stern et al, using HST



Occultation an eclipse of a star
Occultationan eclipse of a star


1992 discovery of kbos
1992 Discovery of KBOs

Jewitt & Luu

1992 QB1


In 2004
In 2004...

A comparison of the size of Sedna, the largest known KBO in 2004, to various planets and moons. (NACO Team, 8.2-meter VLT (Yepun), ESO, apod040827)



Halfway around the world for 5 minutes of data

HST

Keck


Kepler s third law
Kepler’s Third Law

Dysnomia’s orbit P=16d  MEris= 1.27 MPluto Houston, we have a problem!



2006 the iau acts
2006, The IAU acts

  • RESOLUTION 5AThe IAU therefore resolves that "planets" and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:(1) A "planet"1 is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.(2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2 , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.(3) All other objects3 except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies". 1 The eight "planets" are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.2 An IAU process will be established to assign borderline objects into either dwarf planet and other categories.3 These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

goodbye “minor planets”


Halfway around the world for 5 minutes of data

RESOLUTION 6AThe IAU further resolves:Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.


Occultation overview
Occultation Overview

Temperature Pressure

Extinction

Flux

Position in shadow

Bending

angle

=>

=>

Refractivity

=>



Lower atmosphere inversion ref elliot person and qu 2003
Lower Atmosphere Inversion(Ref: Elliot, Person and Qu 2003)

  • Small Planet Case

  • No Ray Crossing

  • Geometric Optics

  • Clear Atmosphere


12 june 2006 occultation reconstructed shadow path
12 June 2006 Occultation:Reconstructed Shadow Path

Predicting Occultations Ain’t Easy!



Occultations
Occultations

12Jun2006

18Mar2007

31Jul2007




Conclusions from 2006 data
Conclusions from 2006 data

  • Pluto's bulk atmosphere (geometry):

    • 1988 to 2006, pressure has increased by 0.98 ± 0.09 µbar, a factor of 2.17±0.21

    • For N2 surface vapor pressure equilibrium, this implies an increase in surface temperature of 1.2-1.7 K.

    • Pressures consistant between 2002 and 2006

  • Pluto’s upper atmosphere (model fit):

    • Non-isothermal. dT/dr = -0.127±0.028 K/km

    • Average (103.9±3.2 K) same as 2002 (104±2 K, isothermal fit), and 1988 (104.0±7.3 K).

    • 99.4±3.1 K (ingress, 30.0 S, summer), 105.5±3.5 K (egress, 53.2 N, winter) despite ~1500 less insolation averaged over the winter latitude, so not tied to insolation (in a straightforward way)

  • Pluto’s lower atm, clear assumption (inversion):

    • As in 1988 & 2002, not isothermal.

    • Temperature inversion around 1210 - 1220 km.

    • Ingress & Egress are qualitatively similar, but the density perturbations differ in detail.

  • Pluto’s lower atm, haze assumption (inversion, removing haze from model fit)

    • Top of haze poorly constrained.

    • Temperature perturbations qualitatively similar to those seen on Earth, Jupiter, Titan


Observations mt john blue channel l 627 nm
Observations - Mt. John(Blue channel; l < ~627 nm)


Observations mt john red channel l 627 nm
Observations - Mt. John(Red channel ; l > ~627 nm)




New horizons on its way
New Horizons on its way


Halfway around the world for 5 minutes of data

July 13th, 2015