Kuiper Belt (Pluto),
and Comets
LACC: §12.3, 12.4, 13.3
• Understand the non-planet bodies in our outer
solar system: Kuiper Belt, Oort Cloud of
comets.
• Comets tell us about our solar system:
composition and history.
• Know the two dwarf planets: Pluto, Eris.
An attempt to answer the “big questions”: what is
out there? Are we alone?
Monday, October 26, 2009 1

Kuiper Belt Objects (KBOs)
The Moon is
obviously
Eris is not a KBO.
technically a It is shown
Scattered here only for
Disc Object Eris
size
(SDO) comparison.
http://www.tng.iac.es/news/2006/01/16/2005fy9/
Monday, October 26, 2009 2

Kuiper Belt
http://lasp.colorado.edu/~bagenal/1010/SESSIONS/17.PlutoCharon.html
Monday, October 26, 2009 3

Trans-Neptunian Objects
While wikipedia is not as reliable as a .gov or .edu site, this illustration was too good to pass up.
http://en.wikipedia.org/wiki/Trans-Neptunian_object
Monday, October 26, 2009 4

Centaur: Chiron
The appearance of a coma may be real.
The largest of [the
Centaurs] is Chiron which
is about 170 km in
diameter, 20 times larger
than Halley. If it ever is
perturbed into an orbit
that approaches the Sun
it will be a truly
spectacular comet.
http://www.ifa.hawaii.edu/~meech/rot.html http://www.nineplanets.org/kboc.html
Monday, October 26, 2009 5

KBO: Pluto -- Dwarf Planet
http://apod.nasa.gov/apod/ap010319.html
Monday, October 26, 2009 6

KBOs: Pluto and Its 3 Moons
Little is known about Pluto's
atmosphere, but it probably consists
primarily of nitrogen with some
carbon monoxide and methane. It is
extremely tenuous, the surface
pressure being only a few microbars.
Pluto's atmosphere may exist as a
gas only when Pluto is near its
perihelion; for the majority of Pluto's
long year, the atmospheric gases are
frozen into ice. Near perihelion, it is
likely that some of the atmosphere
escapes to space perhaps even
interacting with Charon. NASA
mission planners want to arrive at
Pluto while the atmosphere is still
unfrozen.
http://www.solarviews.com/eng/pluto.htm
Monday, October 26, 2009 7

Pluto and Charon: A binary
planetary system?
This model system has been artificially lit and reoriented so that its equator lies in a
horizontal plane. The scale of time has been altered so that 2 days of simulated time
pass in 1 second of real time.
http://www.planetsalive.com/?planet=Pluto&tab=E
Monday, October 26, 2009 8

Currently, the largest
KBO / SDO: Eris known dwarf planet is
(136199) Eris. Eris is
just slightly larger
than Pluto, but orbits
as far as twice Pluto's
distance from the
Sun. Eris is shown
above in an image
taken by a 10-meter
Keck Telescope from
Hawaii, USA. Like
Pluto, Eris has a
moon, which has
been officially named
by the International
Astronomical Union
as (136199) Eris I
(Dysnomia). Eris was
discovered in 2003,
and is likely
composed of frozen
water-ice and
methane. Currently,
the only other
officially designated
"dwarf planet" is (1)
http://apod.nasa.gov/apod/ap060918.html Ceres.
Monday, October 26, 2009 9

Dwarf Planets on Parade
http://www.windows.ucar.edu/tour/link=/our_solar_system/dwarf_planets/
dwarf_planets.html
Monday, October 26, 2009 10

Dwarf Planets to Scale
http://www.windows.ucar.edu/tour/link=/our_solar_system/dwarf_planets/images/
dwarf_planet_sizes_big_jpg_image.html&edu=high
Monday, October 26, 2009 11

Dwarf Planets to Scale
The three known dwarf planets along
side some well known moons. (There
are other moons within this size range
that are not shown.)
Eris
http://astro.berkeley.edu/~basri/defineplanet/
Monday, October 26, 2009 12

Comets
http://cometography.com/lcomets/2006p1.html
Monday, October 26, 2009 13

Comet Halley
http://lpmpjogja.diknas.go.id/kc/c/comet/comet.htm
Monday, October 26, 2009 14

Oort Cloud: Morphology
http://www.nature.com/nature/journal/v424/n6949/fig_tab/nature01725_ft.html
Monday, October 26, 2009 15

Kuiper Belt vs. Oort Cloud
http://www.nature.com/nature/journal/v424/n6949/fig_tab/nature01725_ft.html
Monday, October 26, 2009 16

The Parts of a Comet
http://www.galaxyexplorers.org/newsletter/comet_fun_facts.asp
Monday, October 26, 2009 17

A Sun Grazing Comt
...Comet SOHO-6, one
of numerous sungrazing
comets...as its head
enters the equatorial
solar wind region. It
eventually plunged into
the Sun. ...
23 December 1996....
The field of view of this
coronagraph
encompasses 8.4 million
kilometers (5.25 million
miles) of the inner
heliosphere.
http://sohowww.nascom.nasa.gov/gallery/images/xmascomet.html
Monday, October 26, 2009 18

Comet Tails
http://www.nasa.gov/lb/audience/forkids/home/CS_Ten_Facts_About_Comets.html
Monday, October 26, 2009 19

Comets: Composition
Conventional wisdom is that “Comets are ... dirty snowballs or
"icy mudballs". They are a mixture of ices (both water and frozen
gases) and dust that for some reason didn't get incorporated into
planets when the solar system was formed. This makes them very
interesting as samples of the early history of the solar
system.” (http://www.nineplanets.org/comets.html)
However, data from the Startdust mission “...implies that while the
comets contain ices that formed at the edge of the solar system,
the rocky materials that actually make up the bulk of a comet's
mass actually formed in the hottest possible conditions. The inner
solar system can be thought of as a factory producing rocky
materials that were distributed outwards to all the bodies and
regions of the solar system.” (http://stardust.jpl.nasa.gov/news/
news113.html)
Monday, October 26, 2009 20

Comets: Composition
One of the most remarkable particles found in
the Stardust collection is a particle named
after the Inca Sun God Inti. Inti is collection of
rock fragments that are all related in
mineralogical, isotopic and chemical
composition to rare components in
meteorites called "Calcium Aluminum
Inclusions" or CAI's for short. CAI's are the
oldest materials that formed in the solar
system and they contain a remarkable set of
minerals that form at extremely high
temperature. In addition to these same
minerals, Inti also has tiny inclusions that may
have been the first generation of solids to
condense from hot gas in the early solar
system. These include compounds of titanium,
vanadium and nitrogen (TiN and VN) as well as
tiny nuggets of platinum, osmium, ruthenium,
tungsten and molybdenum. In certain chemical
environments and at high enough temperature
in the early solar system these exotic
materials were the only solid materials that
could survive without being vaporized.
http://stardust.jpl.nasa.gov/news/news113.html
Monday, October 26, 2009 21

Comets on Parade
Temple 1
9 km
0.6 gm/cm3
http://www.sciencenews.org/articles/20050910/bob9.asp
Borrelly
8 km
Wild 2
5 km
0.36 gm/cm3
http://www.aas.org/publications/baas/v36n4/dps2004/317.htm
http://sse.jpl.nasa.gov/planets/profile.cfm?
Object=Comets&Display=Gallery
Monday, October 26, 2009 22

Comet Halley
The nucleus of Comet Halley is approximately 16x8x8 kilometers.
The density of Halley's nucleus is very low: about 0.1 gm/cm3
indicating that it is probably porous, perhaps because it is largely
dust remaining after the ices have sublimed away. (http://
www.nineplanets.org/halley.html)
http://apod.nasa.gov/apod/ap961210.html
Monday, October 26, 2009 23

Shoemaker-Levy 9 struck
Jupiter in 1994
http://apod.nasa.gov/apod/ap001105.html
Monday, October 26, 2009 24

Meteor Showers are Caused
by Comets
When Earth’s orbit passes
through a trail of comet debris,
there are many meteors visible
in a single night--a meteor
shower. The Earth passes
through the meteoroids from
the comet in the same place
each year as it goes around the
Sun, so meteor showers occur
annually. For example, every
August we can see the beautiful
Perseid meteor shower, caused
by the dusty trail that Comet
Swift-Tuttle left behind.
http://cse.ssl.berkeley.edu/SegwayEd/lessons/cometstale/com2place.html
Monday, October 26, 2009 25

Meteor Showers
http://csep10.phys.utk.edu/astr161/lect/meteors/showers.html
More extensive listings of meteor showers can be found, e.g.
http://csep10.phys.utk.edu/astr161/lect/meteors/shower_list.html
Monday, October 26, 2009 26

Review for the Test 3 of 5:
The Outer Solar System
[10 pts] Identify objects from a picture. [10 pts] Asteroids, Comets, etc.
• Jupiter. Saturn, Uranus, Neptune • Location: asteroids--asteroid belt, Trojan asteroids
• Io, Europa, Ganymede, Callisto, Titan, Triton (some meteorites came from the moon or Mars);
• asteroids, comets (parts: nucleus, coma, dust tail, trans-neptunian objects--Centaurs (between
ion tail), Pluto (w/ Charon, Nix, and Hydra) Jupiter and Neptune), Kuiper belt (50 - 100 AU,
outside the orbit of Neptune), Oort Comet Cloud
[10 pts] Jupiter, Saturn, Uranus, Neptune (random elliptical orbits out to 100,000 AU
• Physical properties: mass, size, composition, ring • Composition: asteroids--C, S, and M type;
systems meteorites--iron, stoney iron, stoney (includes
• Orbital properties: axial tilt (Uranus is on its side), carbonaceous chondrites)); comets--parts
length of day, length of year, distance from the sun (nucleus, coma, tail (ion and dust))
• Atmospheres: composition (H, He, etc.), clouds • Notable: Minor Planets--Ceres, Pluto (w/ moons),
(H2O, (NH4)SH, NH3, CH4) depending on the Eris; Centaurs--Chiron; Ida w/ moon Dactyl;
different molecules’ condensation temperatures comet Shoemaker-Levy 9
[10 pts] Moons of Jupiter: Io, Europa, Ganymede, Callisto, [10 pts] Solar System Evolution
Saturn: Titan; and Neptune Triton. • Ring Systems: composition (ices, rocky material),
• Physical and orbital properties: mass, size, origin (moons wander inside Roche limit, debris
composition (Europa and Ganymede may have from meteor impacts on small moons), evolution
significant water oceans under their crust), (shepherd moons keep them tidy, orbital
distance from their planet, Triton orbits resonances with major moons), bright vs dark
backwards, Rhea might have rings (young & icy vs old & dusty)
• Surface features: craters (esp. Callisto), volcanic • Outer planet’s moons (differentiation?), KBOs,
activity (Io, Triton, Enceladus), what causes these comets: icy because they formed outside frost line
moons to be geologically active (tidal forces, • Undifferentiated asteroids are the oldest objects
erupting substances may not be not lava) known (over 4.5 billion years old); differentiated
• Titan’s atmosphere: composition (N2, 1.6 bars), asteroids may be parts of early planetesimals;
methane (CH4) seas and rain? asteroids and comets are samples of the early solar
system containing organic compounds like amino
acids--the building blocks of life
Monday, October 26, 2009 27

LACC HW: Franknoi, Morrison, and
Wolff, Voyages Through the Universe,
3rd ed.
• Ch 12, pp. 286: 4.
Due at the beginning of next class period.
Test covering chapters 10-13 next class period.
Be working your Solar System project.
Monday, October 26, 2009 28