hubble space telescope max mutchler space telescope science institute friends school collection...
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Hubble Space Telescope
Max MutchlerSpace Telescope Science Institute
Friends School CollectionFebruary 6, 2007
Overview
• Hubble mission background• Discovery of Pluto (1930) and moon Charon (1978)• Hubble observations of Pluto: discovery of moons Nix
and Hydra (2005)• Planet vote of 2006: planets and “dwarf planets”• History: how many planets are there?• The “problem” of being first: Ceres & Pluto• Hubble observations of Ceres, another dwarf planet• New Horizons and Dawn missions: follow the data, not
the voting• Inspiring students, and “teachable moments”
Hubble was launched into orbit by the Space Shuttle in 1990
Hubble is serviced in orbit by astronauts
19931997199920022008?
Installed during Hubble Servicing Mission 3B March 2002
Advanced Camera Advanced Camera for Surveys (ACS)for Surveys (ACS)
Space Telescope Science Institute (STScI) on the campus of Johns Hopkins University in Baltimore
The “Home of Hubble”
Hubble observations of Ceres and PlutoHubble observations of Ceres and Pluto
What is a planet ?
Eris a
nd D
ysno
mia
The discovery of Pluto in 1930
ClydeTombaugh
Blink-comparator that Tombaugh used to compare two images,and discover Pluto by it’s motion
The discovery of Pluto’s moon Charon in 1978
James Christy & Robert Harrington
U.S. Naval ObservatoryWashington, D.C.
The discovery of two new moons of Pluto
Weaver, Stern, Mutchler, Steffl, Merline, Buie, Spencer, Young, Young, 2006, Nature, 439
15 May 2005, frame 1
Notice the star trails, cosmic rays, chip gap…
15 May 2005, frame 2
Notice the star trails, cosmic rays, chip gap…
15 May 2005, frame 3
Dithering across the chip gap now…see anything?
15 May 2005, frame 4
Dithering across the chip gap now…see anything?
15 May 2005, sum 4 frames
Looking for real objects among all the artifacts…
Hubble ACS image on 15 May 2005
Pluto
Charon
Hydra
Nix
Pluto
Charon
Hydra
Nix
Hubble ACS image on 18 May 2005
15 and 18 May 2005, median 8 frames
Hydra (P1)
Charon
Nix (P2)
New moons are roughly 3-4x farther out than Charon, andco-planar with possible 6:4:1 orbital resonances
What does a “quadruple planet” look like?What does a “quadruple planet” look like?http://www.stsci.edu/~mutchler/pluto_50.html
Animations produced with
Celestia
NixNix
HydraHydra
~100 km~100 km
Relative sizes of Pluto, Charon, and new moons
2300 km 1200 km2300 km 1200 km
The new moons are roughly 12x smaller and 600x fainter than Charon, and 4000x fainter than Pluto
Common origin of Pluto and all 3 moons: a giant impact ~4 billion years ago
Similar to Earth-Moon formation?
The planet vote of 2006…and the reaction
The 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” 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) shape, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.
http://www.iau2006.org
Final Resolution 5 for GA-XXVI: Definition of a Planet24 August 2006
Is Charon a satellite,
or part of a binary
dwarf planet ?
Nix
Hydra
…and Ceres are “dwarf planets”?
Y Y YY Y Y
Y ? ?Y ? ?
Eris
Dysnomia
Historical perspective:how many planets are there?
• Antiquity -- 7 planets in geocentric model (Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn)
• 1550 – 6 planets in heliocentric model (add Earth, remove Moon and Sun); the reaction was truly Medieval!
• 1781 – 7 planets (add Uranus) • 1807 – 11 planets (add Ceres, Pallas, Juno, Vesta) • 1845 – 12 planets (add Astraea) • 1846 – 13 planets (add Neptune) • 1851 – 8 planets (too many objects in Asteroid Belt to include them
all – feeling any déjà vu yet?) • 1930 – 9 planets (add Pluto)• 1992 – Discovery of 1992 QB1…the Kuiper Belt! • 2005 – Discovery of Eris (UB313)• 2006 – 8 planets (remove Pluto; don’t add Ceres, Charon, Eris or
other “dwarf planets”)
Ceres
Asteroid Belt Kuiper Belt Discovered 1801-1851 Discovered in 1992…or 1930?
Ceres and Pluto: The “ugly duckling”problem of being the first of an entire class
Inferring planets from extra-solar Kuiper Belt’s (vice versa): where planetary meets stellar astronomy
Will our planet definition
work for the other 6 billion planets
in our galaxy ?
Ground-based Hubble Hubble undithered dithered
High resolution images of Ceres reveal roundness, surface features, and colors
Ground-based Hubble Hubble undithered dithered
High resolution images of Ceres reveal roundness, surface features, and colors
Three different faces of Ceres
Three different faces of Ceres
Why does roundness matter ?
Differentiation of the asteroid Ceres as revealed by its shape Thomas, Parker, McFadden, Russell, Stern, Sykes, Young, 2005, Nature Letters, Vol 437
Jim Christy
Annette and Patsy TombaughAnnette and Patsy Tombaugh
Jim Christy Jim Christy
New HorizonsNew Horizons launch launch19 January 200619 January 2006
http://www.dawn-mission.org http://pluto.jhuapl.edu
Dawn New Horizons
Pluto 2015
Vesta2011
Ceres2015
A “teachable moment”
• Pluto has not changed at all • Classification is an important tool in science;
imperfect, but allows us to move forward• Progress is sometimes messy, the truth often
seems counterintuitive at first – not determined by a vote
• Science is not a static body of facts, it is an ongoing process of discovery and debate
I’m delighted when Hubble inspires kids…I’m delighted when Hubble inspires kids…
……because I because I was inspiredwas inspired