Pluto– Planet or Largest Kuiper Belt Object? • Life in...
17
Mar 18, 2005 Astronomy 210 Spring 2005 Astronomy 210 Section 1– MWF 1500-1550 134 Astronomy Building This Class (Lecture 25): Debris Next Class: Birth of the Solar System Music: Amy Hit the Atmosphere – Counting Crows 2 nd Hour Exam in 2 weeks! Mar 18, 2005 Astronomy 210 Spring 2005 Outline • Pluto– Planet or Largest Kuiper Belt Object? • Life in our Solar System? • Comets– You Dirty Iceball • Asteroids– Spacecraft hazard? • Meteroids– watch your head No lunar landscape, no Martian desert can compare to the terrifying solitude of Pluto. Patrick Moore and David A. Hardy Challenge of the Stars (1972) Mar 18, 2005 Astronomy 210 Spring 2005 Clyde Tombaugh (1906 – 1997) The Discovery of Pluto • Astronomers calculated that there must be another body perturbing the orbits of Uranus and Neptune • Percival Lowell calculated that “Planet X” must have a mass 7 times that of the Earth • Clyde Tombaugh was hired to look for it • In 1930, he found a planet • In honor of Lowell, it was named Pluto (P.L.)
Transcript of Pluto– Planet or Largest Kuiper Belt Object? • Life in...
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
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5
Ast
rono
my
210
Sect
ion
1–M
WF
150
0-15
5013
4 A
stro
nom
y B
uild
ing
Thi
s C
lass
(L
ectu
re 2
5):
Deb
ris
Nex
t Cla
ss:
Bir
th o
f th
e So
lar
Syst
em
Mus
ic: A
my
Hit
the
Atm
osph
ere
–C
ount
ing
Cro
ws
2ndH
our
Exa
m in
2 w
eeks
!
Mar
18,
200
5A
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nom
y 21
0 Sp
ring
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5
Out
line
•Pl
uto–
Plan
et o
r L
arge
st K
uipe
r B
elt O
bjec
t?
•L
ife
in o
ur S
olar
Sys
tem
?
•C
omet
s–Y
ou D
irty
Ice
ball
•A
ster
oids
–Sp
acec
raft
haz
ard?
•M
eter
oids
–w
atch
you
r he
ad
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
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5
No
luna
r la
ndsc
ape,
no
Mar
tian
dese
rt c
anco
mpa
re to
the
terr
ifyin
g so
litud
e of
Plu
to.
Pat
rick
Moo
re a
nd D
avid
A. H
ardy
Cha
lleng
e of
the
Sta
rs(1
972)
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
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5
Cly
de T
omba
ugh
(190
6 –
1997
)
The
Dis
cove
ry o
f P
luto
•A
stro
nom
ers
calc
ulat
ed th
at th
ere
mus
t be
anot
her
body
per
turb
ing
the
orbi
ts o
f U
ranu
s an
d N
eptu
ne•
Perc
ival
Low
ell c
alcu
late
d th
at
“Pla
net X
” m
ust h
ave
a m
ass
7 tim
es
that
of
the
Ear
th•
Cly
de T
omba
ugh
was
hir
ed to
look
fo
r it
•In
193
0, h
e fo
und
a pl
anet
•In
hon
or o
f L
owel
l, it
was
nam
ed
Plut
o (P
.L.)
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
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5
For
tuna
te M
ista
ke
•It
turn
ed o
ut th
at
Plut
o w
as n
ot
Low
ell’
s “P
lane
t X”
•Pl
uto
has
only
0.
2% th
e m
ass
of
Ear
th, n
ot 7
tim
es
the
mas
s•
Too
sm
all t
o in
flue
nce
Ura
nus
& N
eptu
ne’s
orb
its•
Mod
ern
obse
rvat
ions
and
cal
cula
tions
sho
w n
o “P
lane
t X”
need
ed to
pre
dict
thei
r or
bits
Mar
18,
200
5A
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nom
y 21
0 Sp
ring
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5
Rad
ius
0.19
Ear
thSu
rfac
e gr
avity
0.04
Ear
thM
ass
0.00
2 Ea
rth
Aver
age
Dis
tanc
e fr
om S
un39
.5 A
UTi
lt of
Rot
atio
n Ax
is12
2 de
gree
sO
rbit
ecce
ntric
ity0.
249
Year
248.
6 Ea
rth
year
sSo
lar
day
6.39
Ear
th d
ays
(bac
kwar
ds)
Ear
th -
Plu
to C
ompa
riso
n
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
How
Doe
s P
luto
Mea
sure
Up?
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Plu
to’s
Orb
it
•H
ighl
y ec
cent
ric
•H
ighl
y in
clin
ed
with
re
spec
t to
the
othe
r pl
anet
s•
From
197
9-19
99,
Plut
o w
as c
lose
r to
the
Sun
than
Nep
tune
!•
Nev
er w
ill c
ollid
e be
caus
e of
3:2
res
onan
ce w
ith N
eptu
ne
Mar
18,
200
5A
stro
nom
y 21
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ring
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5
Plu
to’s
Sur
face
•N
o sp
acec
raft
has
ev
er v
isite
d Pl
uto
•O
ur b
est v
iew
of
Plut
o co
mes
fro
m
Hub
ble
•C
over
ed in
nitr
ogen
, m
etha
ne, a
nd c
arbo
n m
onox
ide
ice
•C
urre
nt s
urfa
ce te
mpe
ratu
re -
abou
t 40
K (
-230
C,
-390
F)!
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Plu
to’s
Atm
osph
ere
•O
bser
ved
whe
n Pl
uto
occu
lts
back
grou
nd s
tars
•C
onsi
sts
mos
tly o
f ni
trog
en
(90%
) an
d ca
rbon
mon
oxid
e–
Sim
ilar
to T
rito
n
•A
s Pl
uto
gets
far
ther
fro
m
the
Sun,
atm
osph
ere
may
“f
reez
e ou
t” a
roun
d 20
20
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Plu
to’s
Moo
n, C
haro
n•
In 1
977,
Plu
to w
as
foun
d to
hav
e a
moo
n•
Lar
gest
moo
n re
lativ
e to
hos
t pla
net
–A
bout
120
0 km
acr
oss
–A
bout
12%
Plu
to’s
mas
s
•Su
rfac
e co
vere
d in
w
ater
ice
•B
oth
rota
te s
ynch
rono
usly
–Pl
uto
and
Cha
ron
each
kee
p th
e sa
me
face
poi
nted
tow
ards
the
othe
r
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Plu
to’s
Moo
n, C
haro
n
•In
197
7, P
luto
was
fo
und
to h
ave
a m
oon
•L
arge
st m
oon
rela
tive
to h
ost p
lane
t•
Abo
ut 1
200
km a
cros
s–
Abo
ut 1
2% P
luto
’s m
ass
•Su
rfac
e co
vere
d in
w
ater
ice
•B
oth
rota
te s
ynch
rono
usly
–Pl
uto
and
Cha
ron
each
kee
p th
e sa
me
face
poi
nted
tow
ards
the
othe
r
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Inte
rior
s &
Com
posi
tion
•Pl
uto
is s
imila
r in
den
sity
and
si
ze to
Nep
tune
’s
moo
n T
rito
n•
Lik
ely
a si
mila
r co
mpo
sitio
n, a
ro
ck/ic
e m
ix
(60/
40)
•R
ocky
cor
e, s
urro
unde
d by
wat
er-i
ce m
antle
•Si
nce
it is
sm
alle
r, C
haro
nis
pro
babl
y no
t dif
fere
ntia
ted
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Cu
rren
tly
pla
nn
ed f
or
lau
nch
in 2
006
htt
p:/
/plu
to.jh
uap
l.ed
u
New
Hor
izon
s
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Lif
e in
our
Sol
ar S
yste
m
Con
clus
ions
•N
o co
nclu
sive
evi
denc
e ex
ists
for
life
in o
ur s
olar
sy
stem
bes
ides
on
Ear
th
•B
ut, p
ossi
bilit
ies
exis
t for
life
–V
enus
may
hav
e lif
e in
the
clou
ds th
at m
igra
ted
whe
n po
ssib
le o
cean
s bo
iled
away
.
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Lif
e on
Ven
us?
•Su
rfac
e is
far
too
hot
–If
lead
is li
quid
, thi
nk o
f w
hat h
eat w
ould
do
to
com
plex
org
anic
pol
ymer
s
–N
o co
oler
pol
ar r
egio
ns e
xist
•H
eat i
s un
ifor
m!
•B
ut, h
igh
in th
e cl
ouds
it s
houl
d be
co
oler
?!
–M
aybe
life
can
stil
l exi
st in
the
clou
ds?
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Ven
us C
hem
ical
Dis
equi
libri
um
•A
t 50
km u
p, th
e te
mpe
ratu
re is
not
too
hot a
nd
the
pres
sure
is 1
atm
osph
ere.
•H
igh
clou
ds in
the
atm
osph
ere
cont
ain
chem
ical
s th
at h
int a
t the
pre
senc
e of
som
e ki
nd o
f bi
olog
ical
act
ivity
.
•H
ydro
gen
sulf
ide
and
sulf
ur d
ioxi
de -
two
gase
s th
at r
eact
with
eac
h ot
her–
exis
ts in
the
clou
ds.
•So
met
hing
is p
roba
bly
prod
ucin
g th
em.
•H
ardl
y an
y ca
rbon
mon
oxid
e. S
o so
met
hing
is
perh
aps
rem
ovin
g th
e ga
s.
http
://w
ww
.man
son-
valle
y.de
/fot
ogal
erie
/man
son/
imag
es/a
css
/acs
s_32
.jpg
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Lif
e on
Ven
us?
•O
ne p
ossi
bilit
y is
that
mic
robe
s liv
ing
in th
e cl
ouds
cou
ld
be c
ombi
ning
sul
fur
diox
ide
with
car
bon
mon
oxid
e an
d po
ssib
ly h
ydro
gen
sulp
hide
or
carb
onyl
sul
phid
e in
a
met
abol
ism
sim
ilar
to th
at o
f so
me
earl
y te
rres
tria
l m
icro
orga
nism
s.
•G
iven
that
the
tem
pera
ture
on
Ven
us w
as o
nce
muc
h co
oler
, the
re m
ay o
nce
have
bee
n oc
eans
on
the
plan
et. L
ife
coul
d ha
ve s
tart
ed th
ere
and
retr
eate
d to
sta
ble
nich
es o
nce
the
runa
way
gre
enho
use
effe
ct b
egan
.
•M
aybe
a m
issi
on to
sco
op u
p so
me
atm
osph
ere?
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Lif
e in
our
Sol
ar S
yste
m
Con
clus
ions
•N
o co
nclu
sive
evi
denc
e ex
ists
for
life
in o
ur s
olar
sy
stem
bes
ides
on
Ear
th
•B
ut, p
ossi
bilit
ies
exis
t for
life
–V
enus
may
hav
e lif
e in
the
clou
ds th
at m
igra
ted
whe
n po
ssib
le o
cean
s bo
iled
away
.
–M
ars
may
hav
e so
me
mic
robi
al h
isto
ry li
nked
to w
ater
, an
d pe
rhap
s so
me
subs
urfa
ce li
fe.
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Mar
tian
Mic
robe
s?
•M
icro
scop
ic s
hape
s th
at
rese
mbl
e li
ving
and
fos
sil
bact
eria
on
Ear
th–
nano
bact
eria
. Pe
rhap
s w
e ha
ve m
eet o
ur f
irst
ET
?•
With
new
evi
denc
e of
onc
e liq
uid
wat
er, w
e ca
n fu
rthe
r sp
ecul
ate
wha
t hap
pene
d w
hen
the
plan
et’s
atm
osph
ere
disa
ppea
red,
per
haps
life
m
oved
to th
e su
bsur
face
. G
oing
und
ergr
ound
.
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Lif
e in
our
Sol
ar S
yste
m
Con
clus
ions
•N
o co
nclu
sive
evi
denc
e ex
ists
for
life
in o
ur s
olar
sy
stem
bes
ides
on
Ear
th
•B
ut, p
ossi
bilit
ies
exis
t for
life
–V
enus
may
hav
e lif
e in
the
clou
ds th
at m
igra
ted
whe
n po
ssib
le o
cean
s bo
iled
away
.
–M
ars
may
hav
e so
me
mic
robi
al h
isto
ry li
nked
to w
ater
, an
d pe
rhap
s so
me
subs
urfa
ce li
fe.
–Ju
pite
r’s
atm
osph
ere
is r
ich
in p
re-b
ioti
c m
olec
ules
.
Mar
18,
200
5A
stro
nom
y 21
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ring
200
5
Flo
atin
g L
ife
•M
aybe
sim
ilar
to w
hale
s–m
ixtu
re b
etw
een
jelly
fish
an
d bi
rds?
•B
ig b
ags
of h
yrdr
ogen
gas
feed
ing
on s
mal
ler
mic
robe
s.
•O
f co
urse
, thi
s is
all
spec
ulat
ive,
and
ther
e is
no
way
to d
etec
t suc
h lif
e.
http
://w
ww
.epi
logu
e.ne
t/cg
i/da
taba
se/a
rt/l
ist.p
l?ga
ller
y=31
26
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Lif
e in
our
Sol
ar S
yste
m
Con
clus
ions
•N
o co
nclu
sive
evi
denc
e ex
ists
for
life
in o
ur s
olar
sy
stem
bes
ides
on
Ear
th
•B
ut, p
ossi
bilit
ies
exis
t for
life
–V
enus
may
hav
e lif
e in
the
clou
ds th
at m
igra
ted
whe
n po
ssib
le o
cean
s bo
iled
away
.
–M
ars
may
hav
e so
me
mic
robi
al h
isto
ry li
nked
to w
ater
, an
d pe
rhap
s so
me
subs
urfa
ce li
fe.
–Ju
pite
r’s
atm
osph
ere
is r
ich
in p
re-b
ioti
c m
olec
ules
.
–E
urop
a’s
sub-
crus
talo
cean
s m
ay h
arbo
r lif
e, e
ven
fish
-lik
e lif
e.
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Io•
Inne
rmos
t Gal
ilean
moo
n –
the
“piz
za m
oon”
•T
he m
ost v
olca
nica
lly a
ctiv
e bo
dy in
the
sola
r sy
stem
.•
Voy
ager
1 d
isco
vere
d pr
esen
ce o
f vo
lcan
oes
•In
tern
al h
eatin
g by
Jup
iter’
s tid
es•
Atm
osph
eric
gas
es r
ippe
d of
f by
Jup
iter’
s m
agne
tic f
ield
–io
n to
rus
Pill
anP
ater
aer
uptio
nB
efor
e &
afte
r
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Eur
opa
•Pe
rhap
s lik
e Io
, Eur
opa
is a
lso
heat
ed f
rom
w
ithi
n?•
Lik
ely
that
ther
e is
liqu
id w
ater
bel
ow th
e ic
e su
rfac
e.•
Lif
e co
uld
exis
t bel
ow th
e su
rfac
e ic
e be
low
th
e su
rfac
e, a
roun
d hy
drot
herm
al v
ents
.•
Ear
ly li
fe o
n E
arth
, may
hav
e fo
rmed
ar
ound
suc
h ve
nts.
•W
e do
n’t h
ow th
ick
the
ice
is y
et.
•Fu
ture
mis
sion
s, w
ill h
ave
to
em
ploy
sm
ash
and
dive
spa
cecr
aft.
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Lif
e in
our
Sol
ar S
yste
m
Con
clus
ions
•N
o co
nclu
sive
evi
denc
e ex
ists
for
life
in o
ur s
olar
sy
stem
bes
ides
on
Ear
th
•B
ut, p
ossi
bilit
ies
exis
t for
life
–V
enus
may
hav
e lif
e in
the
clou
ds th
at m
igra
ted
whe
n po
ssib
le o
cean
s bo
iled
away
.
–M
ars
may
hav
e so
me
mic
robi
al h
isto
ry li
nked
to w
ater
, an
d pe
rhap
s so
me
subs
urfa
ce li
fe.
–Ju
pite
r’s
atm
osph
ere
is r
ich
in p
re-b
ioti
c m
olec
ules
.
–E
urop
a’s
sub-
crus
talo
cean
s m
ay h
arbo
r lif
e, e
ven
fish
-lik
e lif
e.
–T
itan
is v
ery
inte
rest
ing
•T
hick
atm
osph
ere
•R
educ
ing
chem
istr
y
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Tita
n
Tita
n’s
atm
osph
ere
•L
iqui
d/ic
e hy
droc
arbo
ns?
•O
rgan
ic c
ompo
unds
–li
fe?
•Pr
obab
ly n
ot –
too
cold
: 95
K•
May
be
a “d
eep
free
ze”
of th
e ch
emic
al
com
posi
tion
of a
ncie
nt E
arth
•C
ould
ther
e be
a “
fish
” sw
imm
ing
in li
quid
m
etha
ne?
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
No
Inte
llige
nt L
ife
•W
e m
ight
fin
d ev
iden
ce o
f so
me
sort
of
life
in o
ur
Sola
r Sy
stem
in th
e ne
xt d
ecad
e, b
ut v
ery
unlik
ely
to f
ind
com
plex
ity n
eede
d fo
r in
telli
gent
and
co
mm
unic
ativ
e lif
e.
•A
ppar
ently
in o
ur s
yste
m, E
arth
’s c
ondi
tions
are
ne
cess
ary.
•O
ther
pla
nets
may
hav
e m
icro
bial
for
ms
of li
fe,
and
may
beco
mpl
ex f
ish-
like
orga
nism
s, b
ut w
e do
n’t e
xpec
t com
mun
icat
ive
bein
gs.
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
How
to s
earc
h fo
r lif
e?
•H
ow d
o w
e se
arch
for
life
in o
ur S
olar
Sys
tem
and
be
yond
?•
Wha
t tes
t will
indi
cate
life
exc
lusi
vely
?•
Is is
cle
ar th
at f
utur
e m
issi
ons
need
to la
nd a
s ne
ar a
s po
ssib
le to
site
s of
sub
surf
ace
wat
er o
r ot
her
solv
ents
.•
Wha
t if
the
life
is s
till i
n th
e pr
otol
ife
stag
e? C
an w
e de
tect
that
?•
The
bou
ndar
y be
twee
n ch
emic
al a
nd b
iolo
gica
l pro
cess
es
is d
iffi
cult
to d
istin
guis
h.
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Dec
isio
n T
rees
–Se
arch
for
Lif
e
•W
ait f
or it
to c
ome
to u
s vi
a m
eteo
rite
s or
com
ets.
•R
obot
ic o
ne-w
ay in
vest
igat
ions
–M
ars
rove
rs.
•Fe
tch
and
retu
rn w
ith s
ampl
es.
http
://w
ww
.ibib
lio.
org/
wm
/pai
nt/a
uth/
frie
dric
h/tr
ee.jp
g
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Pro
blem
s
•In
the
last
2 c
ases
, we
have
the
prob
lem
of
cont
amin
atio
n by
E
arth
life
.
•O
rgan
ism
s ca
n liv
e in
Mar
s-lik
e co
nditi
ons
on E
arth
.
•If
som
e E
arth
life
sur
vive
s th
e sp
ace
jour
ney,
it c
ould
col
oniz
e M
ars,
pos
sibl
y de
stro
y an
y M
artia
n lif
e. T
hink
of
Kud
zu.
•C
urre
nt m
issi
ons
mus
t be
ster
ilize
d.ht
tp://
ww
w.h
ope.
edu/
acad
emic
/bio
logy
/fac
ulty
/eva
ns/i
mag
es/A
ngio
sper
ms/
Cor
eEud
icot
s/E
uros
idsI
/Fab
acea
e/K
udzu
.JP
G
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Bio
mar
kers
: H
ow to
look
for
ext
raso
lar
life.
•W
e ne
ed to
dec
ide
how
to s
earc
h fo
r bi
omar
kers
or
chem
ical
si
gnat
ures
of
life.
•O
n E
arth
, met
hane
and
oxy
gen
are
indi
cato
rs.
The
y no
rmal
ly
reac
t. S
omet
hing
is k
eepi
ng it
ou
t of
equi
libri
um.
Sort
of
like
Ven
us d
iseq
uilib
rium
.
•T
he G
alile
o sp
acec
raft
on
its w
ay
out t
o Ju
pite
r, tu
rned
and
look
ed
at th
e E
arth
.
•D
id it
det
ect l
ife?
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Bio
mar
kers
: L
ooki
ng a
t Ear
th.
•St
rong
“re
d ed
ge”
from
ref
lect
ed li
ght.
Abs
orpt
ion
from
ph
otos
ynth
esis
.•
Stro
ng O
2. K
eepi
ng o
xyge
n ri
ch a
tmos
pher
e re
quir
es s
ome
proc
ess.
It s
houl
d sl
owly
com
bine
with
roc
ks.
•St
rong
met
hane
. Sho
uld
oxid
ize.
Rep
leni
shed
by
life.
•St
rang
e ra
dio
emis
sion
s th
at c
ould
be
inte
llige
nt li
fe.
•R
ecen
tly, r
esea
rche
rs h
ave
look
ed a
t the
Ear
thsh
ine
from
the
moo
n.•
The
y ag
ree
with
Gal
ileo
resu
lt.
The
re is
life
on
Ear
th.
–W
ater
–O
xyge
n–
Ten
tativ
e de
tect
ion
of “
red
edge
”
http
://e
pod.
usra
.edu
/arc
hive
/epo
dvie
wer
.php
3?oi
d=56
256
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Bey
ond
Plu
to –
The
Kui
per
Bel
t
•A
“re
serv
oir”
of
icy
bodi
es b
eyon
d Pl
uto
•Pr
opos
ed to
exp
lain
sh
ort-
peri
od c
omet
s
•T
he f
irst
Kui
per
Bel
t O
bjec
t (K
BO
) w
as
dete
cted
in 1
992
•T
ypic
al s
izes
10
-50
km, v
ery
fain
t–
Smal
l one
s ar
e po
tent
ial c
omet
s
–A
few
are
larg
e, h
undr
eds
of k
m a
cros
s
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Qua
oar
& S
edna
•C
urre
ntly
the
larg
est k
now
n K
BO
s•
Prob
ably
si
mil
ar in
co
mpo
sitio
n to
Cha
ron
•Su
rfac
e te
mpe
ratu
res
arou
nd 3
0 K
(-2
40 C
)!
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Dis
cove
ry im
ages
Qua
oar
•O
rbita
l dis
tanc
e ~
42 A
U
•A
bout
50%
the
diam
eter
of
Plu
to
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Sedn
a
•A
bout
75%
the
diam
eter
of
Plut
o
•C
urre
ntly
at 6
7 A
U f
rom
the
Sun
•O
rbit
take
s it
over
90
0 A
U a
way
•10
,500
yr
orbi
t
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Plu
to, P
lane
t or
KB
O?
•Pl
anet
?–
Odd
pla
net:
all
othe
r ou
ter
plan
ets
are
gian
ts–
Ver
yec
cent
ric
orbi
t–
Orb
it hi
ghly
tilte
d w
ith r
espe
ct to
the
othe
r pl
anet
s
•K
uipe
r B
elt O
bjec
t?–
Lar
ger
than
oth
er K
BO
s(b
ut c
lose
in s
ize
to Q
uaoa
r&
Sed
na)
–H
as a
n at
mos
pher
e (l
ike
Tri
ton)
•B
ecau
se o
f si
ze &
clo
sene
ss to
the
Sun
–T
ypic
al K
BO
com
posi
tion
(icy
-roc
k m
ix)
–O
rbit
typi
cal f
or a
KB
O
•M
any
KB
Os
are
also
in r
eson
ance
with
Nep
tune
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Pla
net?
Und
efin
ed!
•W
e ha
ve n
ode
fini
tion
of
a pl
anet
!–
Its
like
art:
We
know
on
e w
hen
we
see
it
•If
Plu
to is
a
plan
et, w
hy n
otSe
dna
or Q
uaoa
r?
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Way
s of
Def
inin
g a
Pla
net
1.H
isto
rica
l–
Just
the
orig
inal
nin
e!
2.H
isto
rica
l Plu
s–
Any
thin
g bi
gger
than
Plu
to
–…
and
not s
omet
hing
’s m
oon!
3.G
ravi
tatio
nally
Rou
nd–
Big
eno
ugh
that
its
grav
ity m
akes
it r
ound
4.Po
pula
tion
Cla
ssif
icat
ion
–Is
olat
ed b
odie
s vs
. mem
bers
of
larg
e po
pula
tions
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Cla
ss Q
uest
ion
Plut
o. I
s it
a pl
anet
, or
is it
a K
uipe
r B
elt O
bjec
t?
How
do
you
thin
k Pl
uto
shou
ld b
e cl
assi
fied
?
Dis
cuss
this
with
you
r cl
assm
ates
and
wri
te d
own
your
gro
up’s
con
clus
ion.
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Com
ets
•A
ppar
ition
s th
at a
ppea
r lik
e gh
ostly
fir
ebal
ls f
roze
n in
the
sky
•In
anc
ient
tim
es, t
he a
ppea
ranc
e of
a c
omet
was
oft
en c
onsi
dere
d a
harb
inge
r of
doo
m•
Iron
ical
ly, l
ife
on E
arth
may
ha
ve b
een
impo
ssib
le w
ithou
t th
em•
Als
o co
met
s an
d m
eteo
roid
s ar
e th
e ol
dest
ori
gina
l sol
ar s
yste
m
mat
eria
l! L
eft o
ver
build
ing
mat
eria
ls.
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Wha
t is
a C
omet
?
•D
irty
iceb
ergs
in
spa
ce–
10-5
0 km
ac
ross
•C
ompo
sed
mos
tly o
f w
ater
ic
e (b
ut a
lso
CO
2
and
CH
4), w
ith
som
e so
lid d
ust,
rock
&
met
al–
Dar
k su
rfac
es!
•V
ery
ellip
tical
orb
its ⇒
vary
ing
r im
plie
s va
ryin
g T
•W
hen
one
appr
oach
es th
e Su
n, s
unlig
ht s
ublim
ates
M
ar 1
8, 2
005
Ast
rono
my
210
Spri
ng 2
005
Com
ets
Cha
ngin
g r
impl
ies
a ch
ange
in T
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Com
ets
•C
oma
–Su
nlig
ht e
vapo
rate
s co
met
su
rfac
e–
Form
s a
clou
d of
gas
& d
ust
arou
nd th
e nu
cleu
s
•T
ails
–G
as is
ioni
zed
by th
e su
n’s
UV
lig
ht
–G
as &
dus
t pus
hed
away
by
the
sola
r w
ind
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Whe
re D
o C
omet
s L
urk?
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Whe
re D
o C
omet
s L
urk?
•T
he v
ast m
ajor
ity li
ve f
ar o
ut in
the
Sola
r Sy
stem
, bey
ond
the
plan
ets
•Sh
ort p
erio
d co
met
s: K
uipe
r B
elt (
aka
tran
s-N
eptu
nian
)–
Orb
ital p
erio
ds o
f hu
ndre
ds o
f ye
ars
–A
roun
d an
d be
yond
the
orbi
t of
Plut
o (3
0-50
0 A
U),
pr
obab
ly f
orm
ed th
ere.
–N
ow a
bout
240
ish
the
size
of
10%
Plu
to
•L
ong-
peri
od c
omet
s: O
ort C
loud
–E
dge
of S
un's
gra
vita
tiona
l inf
luen
ce
–O
ut to
50,
000
AU
–Pe
riod
s >
105
yrs
–Pr
obab
ly d
id n
ot f
orm
ther
e. E
ject
ed b
odie
s by
Jov
ians
.
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Fal
ling
Into
the
Sola
r Sy
stem
•O
ccas
iona
lly, c
omet
orb
its
get “
pert
urbe
d” b
y pa
ssin
g st
ars
•T
hey
fall
into
the
inne
r So
lar
Syst
em o
n hi
ghly
elli
ptic
al
orbi
ts
•In
tera
ctio
ns w
ith p
lane
ts c
an
shor
ten
thei
r or
bits
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Lif
e &
Dea
th o
f a
Com
et•
Eve
n co
met
s on
sho
rten
ed o
rbits
liv
e m
ostly
in th
e ou
ter
sola
r sy
stem
•E
very
orb
it, th
ey lo
se
1% o
f th
eir
mas
ses
to s
olar
ev
apor
atio
n–
Hal
ley’
s C
omet
will
onl
y la
st a
bout
56
00 m
ore
year
s
•W
hen
they
bec
ome
too
smal
l, th
ey
brea
k ap
art
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Lif
e &
Dea
th o
f a
Com
et
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Dee
p Im
pact
http
://r
eals
erve
r1.jp
l.nas
a.go
v:80
80/r
amge
n/V
ideo
-NA
SA
1st-
Pesr
son-
Yeo
man
s-A
VC
2005
-016
.rm
Dee
p Im
pact
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Dis
cove
ry o
f th
e A
ster
oids
•In
180
1, G
iuse
ppe
Piaz
zino
ticed
an
unch
arte
d “s
tar”
th
at s
hift
ed p
ositi
on a
mon
g th
e st
ars
over
sev
eral
nig
hts
•C
ould
it b
e an
othe
r pl
anet
?–
Its
orbi
t was
bet
wee
n M
ars
and
Jupi
ter
–V
ery
dim
, so
it m
ust b
e sm
all
–T
oo s
mal
l to
be a
pla
net
•It
was
an
aste
roid
, a “
min
or p
lane
t”
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Ast
eroi
ds
•Sm
all s
izes
–L
arge
st –
Cer
es: 9
40 k
m a
cros
s–
Onl
y 3
mor
e th
an 3
00 k
m–
Abo
ut 2
40 b
igge
r th
an 1
00 k
m–
Mill
ions
und
er
1 km
•C
ompo
sitio
n–
Roc
ks (
silic
ates
) an
d ir
on/n
icke
l
Ida
and
Dac
tyl f
rom
Gal
ileo
55 k
m
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
The
Ast
eroi
d B
elt
•M
ost a
ster
oids
are
fo
und
betw
een
2 to
3.5
AU
–B
etw
een
Mar
s &
Ju
pite
r
–R
egio
n is
cal
led
the
Ast
eroi
d B
elt
–N
earl
y ci
rcul
ar o
rbits
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
The
pos
sibi
lity
of s
ucce
ssfu
lly
navi
gatin
g an
ast
eroi
d fi
eld…
•A
ctua
lly, N
ASA
ha
s se
nt m
any
spac
e pr
obes
in
to a
nd th
roug
h th
e A
ster
oid
Bel
t•
Unl
ike
in S
tar
War
s, th
e A
ster
oid
Bel
t is
not t
hat c
row
ded
•A
vera
ge s
epar
atio
n be
twee
n si
zabl
e as
tero
ids
is 1
0 m
illio
n km
!
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Des
troy
ed…
by
the
Em
pire
•A
re th
e as
tero
ids
a de
stro
yed
plan
et?
No
–C
ombi
ned,
the
aste
roid
s ha
ve a
mas
s ab
out 0
.1%
th
at o
f th
e E
arth
–L
ess
than
10%
that
of
our
Moo
n
•T
he a
ster
oids
mig
ht b
e a
fail
edpl
anet
–Ju
pite
r’s
grav
ity k
ept t
he a
ster
oids
fro
m c
oale
scin
g in
to
a pl
anet
–Ju
pite
r pr
obab
ly e
ject
ed m
any
aste
roid
s fr
om th
e So
lar
Syst
em
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Apo
llos
and
Tro
jans
•So
me
aste
roid
s ar
e on
orb
its th
at c
ross
E
arth
’s o
rbit
–C
alle
d A
pollo
ast
eroi
ds–
At l
east
169
0 ar
e kn
own
–In
197
2, o
ne s
kipp
ed
off
the
Ear
th’s
at
mos
pher
e
•O
ther
ast
eroi
ds s
hare
Ju
pite
r’s
orbi
t!–
Cal
led
Tro
jan
aste
roid
s–
Lea
d an
d tr
ail J
upite
r ar
ound
the
Sun
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Lan
ding
on
Ero
s
•In
200
1, N
ASA
land
ed a
sp
acec
raft
on
the
aste
roid
Ero
s
•H
eavi
ly c
rate
red
surf
ace
•B
ould
ers
buri
ed in
the
rego
lith
•A
ncie
nt –
4.6
billi
on y
ears
old
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Ast
eroi
ds -
Ear
ly S
olar
Sys
tem
L
efto
vers
•T
he a
ster
oids
wer
e to
o sm
all t
o ha
ve m
uch
inte
rnal
hea
t –
No
diff
eren
tiatio
n
–N
o ge
olog
ic a
ctiv
ity
–T
he s
ame
as w
hen
they
for
med
4.
6 bi
llion
yea
rs a
go
•Fo
ssils
of
the
earl
y so
lar
syst
em!
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Met
eors
•W
hen
you
see
a “s
hoot
ing
star
”,
that
is a
met
eor
–A
pie
ce o
f so
lar
syst
em d
ebri
s (a
m
eteo
roid
) in
tera
ctin
g w
ith o
ur
atm
osph
ere
•M
ost “
burn
up”
or
disi
nteg
rate
in
the
uppe
r at
mos
pher
e, b
ut s
ome
do
surv
ive
fall
–T
hese
are
met
eori
tes
•C
ompo
sitio
n: r
ock,
som
e m
etal
s
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
S. N
umaz
awa
Met
eor
Show
ers
•M
eteo
rs h
it E
arth
all
the
time
•In
the
earl
y m
orni
ng, y
ou c
an
typi
cally
see
abo
ut 3
per
hou
r•
Seve
ral t
imes
a y
ear,
the
rate
in
crea
ses
–M
aybe
mor
e th
an a
met
eor
per
min
ute
–C
alle
d m
eteo
r sh
ower
s
•Se
em to
ori
gina
te f
rom
a
sing
le p
oint
in th
e sk
y
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Met
eor
Show
ers
•W
hen
a co
met
ent
ers
the
inne
r So
lar
Syst
em, i
t lea
ves
a tr
ail o
f du
st•
Whe
n E
arth
pas
ses
thro
ugh
this
dus
t, w
e ge
t a m
eteo
r sh
ower
•M
eteo
r sh
ower
s do
n’t
typi
cally
pro
duce
met
eori
tes
–It
s al
l dus
t, no
t roc
ks
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Pee
kski
ll F
ireb
all
(Oct
ober
9, 1
992)
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Typ
es o
f M
eteo
rite
s
•94
% o
f m
eteo
rite
s ar
e st
ony
–M
ade
of s
ilica
tes,
ha
rd to
dis
tingu
ish
from
Ear
th r
ocks
•5%
are
iron
s–
Iron
-nic
kel c
ryst
als
•1%
sto
ny-i
rons
–Si
licat
es w
ith ir
on in
clus
ions
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Met
eori
tes
are
Anc
ient
•M
eteo
rite
s ar
e th
e ol
dest
ob
ject
s in
the
Sola
r Sy
stem
•R
emna
nts
of th
e So
lar
Syst
em’s
for
mat
ion
•T
he o
ldes
t are
car
bona
ceou
s ch
ondr
ites
(a ty
pe o
f st
one)
–A
bund
ant i
n ca
rbon
and
wat
er–
Con
tain
am
ino
acid
s -
build
ing
bloc
ks o
f lif
e!–
4.56
bill
ion
year
s ol
d
•So
me
have
dia
mon
ds p
rodu
ced
by in
ters
tella
r sh
ock
wav
es!
Car
bona
ceou
s ch
ondr
ite
Mar
18,
200
5A
stro
nom
y 21
0 Sp
ring
200
5
Met
eori
te O
bser
ving
•T
he U
ofI
has
a sm
all m
eteo
rite
col
lect
ion
in th
e N
atur
al H
isto
ry B
uild
ing
•A
ctiv
ities
:–
Cou
nt th
e nu
mbe
rs o
f ea
ch ty
pe o
f m
eteo
rite
, com
pare
to
the
frac
tions
that
exi
st in
spa
ce–
Why
do
we
know
whe
n m
ost o
f th
e st
ony
met
eori
tes
fell,
but
not
the
iron
one
s?–
Vis
it a
web
-site
, lea
rn a
bout
how
to id
entif
y m
eteo
rite
s
•E
xtra
Cre
dit R
epor
t: D
ue A
pril
8th, w
orth
1/3
a
hom
ewor
k.
