joy to be your host I am dr. Frank
summers of the office of public outreach
and we have an amazing audience here for
you tonight Bonnie Saturn really sells
okay
so we have a packed house here tonight
we may not have anymore we have a couple
lithographs down here we started out
giving out the monkey head nebula we
sold out of the monkey head we had to go
to the 30 Doradus which is also known as
the tarantula nebula so if you didn't
get monkeys you got tarantulas okay and
if you're afraid of spiders well I'm
sorry that's all we have left please
come down and grab one if you didn't on
the way in our talk do i neva need to
say tonight turn this on our talk is
Cassini's grand finale at Saturn and
we've been only waiting 19 years and 11
months for this because that's when the
Cassini launched 19 years and 11 months
ago absolutely looking forward to it
it's a lot of fun upcoming next month
Elizabeth Tasker from the Japan
aerospace exploration agency she'll be
coming in and talking about dangerous
worlds yes exoplanets and such alright
and you can see our familiar TBA coming
in in December in January which means I
was working on some stuff for the end of
the fiscal year and didn't nag people to
sign up for talks actually I have one
scheduled for January but we may have to
change that I don't know with the news
so anyways okay so on the 9th great we
can do it on the night okay okay
ooh tag team on the 9th okay we have
still have some there's a couple extra
seats down here if the folks you're
standing in the corner would like to if
you have a seat next to you raise your
hand so these guys can don't have to
stand for the whole whole night okay all
right let's see website if you go if you
use your favorite search engine and look
for Hubble public talks you'll find this
page with the list of the upcoming
lectures the links to watching it live
on
line as well as in the archive and the
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actually also we send out the monthly
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can send them to public lecture at STScI
dot edu if you would like social media
we have Facebook Twitter YouTube
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that I'm not haven't listed here I
myself I'm on Facebook Google+ and
Twitter every now and then and have a
blog on Hubbell site if you want to
follow me the observatory yes the
weather appears to be permitting tonight
and ireenie sent me a text and said yes
she will be doing it so we will be
meeting at that door over there
okay now unfortunately and it's really
hard to tell an audience of this size
she can only take 15 to 20 people over
okay and I know there's like 200 of you
here tonight so if you have been before
please let somebody else who hasn't been
and if you don't get to go tonight
please come back and and you will be
able to do it after another lecture or
you can go to MD dot space grant o RG
find this webpage and they have open
houses most every Friday evening ok they
update this webpage at like 6:00 p.m. or
5 or 6 p.m. on Friday to tell you
whether or not it will be open and you
will get a longer observing session at
their open house then you will get after
the lecture here ok and as we're going
into fall we've just passed the equinox
the nights get longer and so lots and
lots of observing is possible ok alright
and now my part news from the universe
for October 2017
unfortunately the top story tonight is
JWST launch delay
no no no you got to do that all together
one two three thank you okay so this is
the J this is a drawing of the James
Webb Space Telescope it will be NASA's
next great Observatory it is an infrared
telescope with a six and a half meter
mirror 18 segments it will be launched
and go out a million miles from Earth so
it is nice and cool and away from the
influence of Earth
it'll have these great sun shields to
also keep it cool it will do amazing
things it will do things Hubble cannot
do but it won't do them on the timescale
we had hoped it would do them okay it
was slated to launch in October 2018
that is no longer the launch date NASA
had a press release last week and I'm
quoting from it it says is now is
planning to launch between March and
June of 2019 so it's about a six-month
slip in the schedule it is not
indicative of hardware or technical
performance concerns they want to make
sure that look everything's going fine
we just want to make sure it's perfect
because unlike Hubble we can't go out
and service this okay so integration of
the various spacecraft elements is
taking longer than expected all right
and they want to make sure they do it
right and one other thing in terms of
the financials the existing program
budget accommodates the change in launch
date so you as taxpayers are not going
to pay extra for this delay it's all
within the program budget they build a
lot of contingencies into these plans
and unfortunately we've had to add take
take one of those contingencies so
instead of October 2018 we're looking
between March and June of 2019 it will
be worth it though okay
it really will all right our second
story a tale of two comets yes I know I
didn't quite come up with a real
Dickensian story to go here but I just
like the title all right so first of all
what we're talking about here is the
asteroid
belt okay this is the orbit of Jupiter
out here and in here we have in the
center we have the orbits of Mercury
Venus Earth and Mars in between where
you see all these green things and the
red things those are the main belt
asteroids there are several hundred
thousand of these asteroids however also
in that area are a lot of comets a lot
of short period comets and we're gonna
talk about an object that is actually
both here so in November 2006 they
discovered an asteroid they called it
2006 VW 139 that's thus the standard
nomenclature that we give to asteroids
when we discover them and then they
observed the same object in November
2011 and they found that it had a tail
and tails indicate that it's a comet so
they also gave it the designation of
Comet two eight eight P alright so it
had both asteroid designations and comet
a comet designation well that's
obviously an interesting object so what
are you gonna do you're gonna take
Hubble and you're gonna look at it and
Hubble looked at it in August of 2016
and Hubble saw this ooh what do we see
we see in the center not one but two
bright spots in the center so as you can
see I've updated it to be a binary
asteroid 2006 WV 139 and I guess you can
call it a double nucleus comet two eight
eight P we have an object that appears
to be two objects now in examining it
and trying to understand it they
estimate that it was a single object
that broke apart about five thousand
years ago and then the gases that are
exposed caused jets and then the two
pieces moved away from each other okay
that also produced material that streams
out as this tail so Hubble looked at it
not just once but five times
and we looked at in September first in
September ninth in September 20th and
September 29th and what do we see we see
the tail wagging okay yes comets wag
their tails right um so here are those
five images but you can see they only
occur over this time scale of about a
month now some of the change of the
orientation of the tail is due to the
geometry of earth and and the comet or
asteroid as it was but over the course
of a month it wouldn't change that far
so what they really think that it's also
due to different types of particles
being emitted the larger particles are
here these are on order millimeter sized
when I say large we're talking tiny tiny
dust particles okay this is a dust tail
a tiny tiny dust pyloric is about one
millimeter those are large in
astronomical terms here oh one
millimeter in size are blowing off in
this direction due to how they're being
ejected but by this time the emission
the dust was mostly very very small
about 1/100 that size or 10 microns and
those 10 micron particles get actually
pushed back by the radiation pressure of
the Sun and so here is where the tail is
actually pointing away from the Sun like
a normal Comet dust tail does and here
is it's not quite pointing away from the
Sun due to the larger particles in it so
we have a really cool object that's part
asteroid part comet and it's able to wag
its own tail kind of cool all right our
final story for you is candles in the
dark now candles is an acronym for a
cosmic assembly deep extra galactic
legacy survey blah blah blah what it
really is is a huge project to study the
development gal of galaxies over time
they got more orbits on Hubble than any
their project in history over 900 Hubble
orbits and they looked at five different
fields looking very deep into these
fields alright and here's one of them
it's called the ultra deep survey and
this is filled with about twenty thirty
thousand galaxies okay and these
galaxies are spread out across across
space but as we look out into space
we're also looking back into time if you
look a billion years out into space
you're seeing that galaxy as it was a
billion years ago if you go three
billion years that's three billion years
ago some of these galaxies are 10 11 12
billion light years away so we're seeing
them as they were 10 11 12 billion years
ago by statistically looking at those
galaxies at different distances we can
assemble a view of galaxies as they were
at different stages of the universe
which gives us a picture of how galaxies
develop so they gave us this data in the
office of public outreach and we said
well the first thing we want to do is we
want to show people those galaxies at
different distances so we created a
visualization by cutting out into
cutting out every one of those twenty
six thousand three hundred and four
galaxies in the catalog and then placing
them into a computer model at their
correct relative distances now we didn't
put them at their absolute correct
distances because then it would be so
long that the fly-through would take
probably two hours to do we want to do
it in a minute or so so we compress them
in the z-direction
but we do have a relatively
scientifically the relative distances
are all proper between the various
galaxies okay can we take the lights
down so some people can see this because
there's a lot of black here take the
lights down there we go that look better
to you guys okay and so here we have the
the visualization of the candles ultra
deep survey field
so that was our experiential
visualization for the candles
alternative survey we also plan on doing
some didactic ones where we'll have
narration and point out some of the the
really cool features of it are the
scientific features of it do we have a
question there was some straight line
I actually choreographed the camera to
fly up near that one white galaxy then
down through that cluster that swooped
through to those three red galaxies so
that you would say add some of that some
I sort of thought of it as a
rollercoaster ride through galaxies
you're traveling about 13 billion light
years in a minute and 13 seconds so
you're violating every known law of
physics each object that you saw in
there is a galaxy we cleaned out all the
stars and all the other artifacts from
it and we're left with twenty-six
thousand three hundred four galaxies for
which we had both an image and a
measured or estimated redshift from the
scientific team that's a great question
so at the end there we went to black we
got to the end of the data set we got to
the greatest distance that Hubble can
see because the galaxies further than
that
their light is redshifted into the
infrared and Hubble can't see them
one of the reasons we want the Jade OST
is to look deeper into the universe
because the light from of those galaxies
isn't the infrared and jaidev's - you
will be able to see the what's similar
resolution to what Hubble has alright
okay now let's go to our featured
speaker tonight our speaker tonight is
Bonnie Meinke she joined us about five
years ago and she has been in the office
of public outreach ever since that time
but about a month ago she got a new
position she in the office of public
outreach she was one of the liaisons
with the j ust team she's now moved over
to the Jade Ernestine Mission office
team and is now at least on top oh so
she just jumped over the fence and it's
working with them she is an expert in
sat and on Saturday and she will here
tonight having done her PhD at the
University of Colorado yes and having
worked at the fleet Rubin age fleet
Science Center yes she didn't give me a
biography she was late enough to come
here so you didn't have to do this
remember and she's overall wonderful
person ladies please welcome dr. Bonnie
monkey
hi everybody I am overwhelmed and a
little intimidated by the audience no
pressure and lots of familiar faces I'm
very happy to see them I yes so Cassini
sadly just ended how many people tuned
in for some of the big events
surrounding the grand finale
alright lots of Saturn files out there I
have no idea what's going on and yeah so
like Frank said this this is a mission
that launched almost 20 years ago it was
October 15 1997 there are people in the
audience that were even alive and I
suspect there then it got to Saturn in
2004 and I remember when that happened I
was a fresh-faced grad student and I
thought hey this is gonna be my mission
and I kind of can't believe that it's
already at its end thirteen years after
that but one of the really amazing
things about the Cassini mission is that
it didn't just change our view of Saturn
it changed our view of our solar system
and of solar systems everywhere so I'm
gonna walk you through the grand finale
and the tour of everything Cassini
learned as a way to bridge to the other
types of planetary science that we now
know about care about are dedicated to
studying okay and I'm gonna cut to the
chase I'm just gonna go ahead and lay it
all on the table the biggest discoveries
of the Cassini mission icy moons we knew
about a whole bunch of them before we
got there we discovered more and we
discovered of the
that we already knew really amazing cool
new things um planetary rings of course
we knew about Saturn's rings it's the
ringed planet everybody knows about this
Galileo studied it and thought it was
amazing we've learned a whole lot of new
stuff in the last 13 years about those
planetary rings that we didn't know you
know a decade ago and then finally to
plan it itself I think that the rings
and the moons get so much attention that
the actual planet itself gets ignored in
some ways but it has all kinds of storms
big hurricanes all kinds of wind
patterns really some interesting things
so those those are those from you know a
geologist is excited about those a
meteorologist is excited about those a
dynamicists and orbit celestial
mechanics enthusiast is excited about
those and so we're I'm gonna I'm gonna
step you through these big discoveries
because like I said they fundamentally
changed our view of Saturn of our solar
system and of other solar systems and I
don't know why my slides keep jumping
around so I'm gonna set the context a
little bit for you guys show you the
Saturn system so this of course is
Saturn the big planet here these are the
rings you have the the classical rings
those are the things Galileo saw big icy
bright pretty rings but those continue
outwards as we skip through some of the
moons and there's an arrow here
lots and lots more moons out this way
including the biggest moon of the Saturn
system Titan how many Titan fans are out
there
I hear there's some some theories about
Titan so I got to follow up with you
guys tonight
about about new ideas about Titan okay
we have that big pretty planet it's
mostly hydrogen helium similar to to
Jupiter seem more similar to Jupiter
than it is to Uranus and Neptune but as
I'll show Saturn tells us a lot about
all of the giant planets like I said
those broad dense readings and the big
dusty rings and in between there's a
bunch of gaps mmm those gaps actually
tell us a whole lot about other solar
systems so I'll step you through that
and finally all of these cool moons so
many moons okay
let's start out with basically the
atmosphere the storms that happen the
weather that happens on Saturn and what
we've learned with the Cassini mission
so it's changed our view of Saturn we
got there and we knew the atmosphere was
gonna be interesting but from distance
it's not as dynamic looking as what
jupiter has jupiter has those big
exciting bands it has the Great Red Spot
this giant hurricane it's lasted for
years and years and years for centuries
we didn't think Saturn was gonna be that
interesting we were wrong scientists
love being wrong it's changed our view
of our solar system because there's
other giant planets as I mentioned
there's Jupiter Saturn Uranus and
Neptune in our in our solar system and
those also have these really complex
atmospheres that we can now tie what
we've learned at Saturn too and finally
it's changed our view of other solar
systems so over the course of Saturn's
are of Cassini's lifetime we have seen
there's a lot of exoplanets out there
I'll take you guys through a little
timeline later but when Cassini launched
we only knew of five other exoplanets
five planets around other stars other
worlds beyond our solar system five one
handful and now we know a thousands so
learning about the types of planets
we're seeing elsewhere is so important
and Cassini helps us study that so let's
dive into the atmosphere here and this
is probably the most iconic of the
Saturn as a planet images this is known
as the hexagon and I'm not talking about
France I'm talking about this amazing
structure here if you notice it's
six-sided one two three four five and
six it's a ball it's in the this is the
North Pole
right here so this is looking straight
down onto Saturn and you can see in this
this this false-color or
representational color image that
there's a whole bunch of structure here
in the atmosphere these are all
different storms knots of different wind
patterns and and density clusters inside
the atmosphere and you can think of that
this looks strange we thought we had
seen it with other means other
observations both ground-based and and a
Voyager flyby we thought we'd seen this
hexagonal structure but we weren't
really sure and it didn't quite click we
weren't sure why this would exist and if
it could exist for decades but now we
know it's there we confirmed it and one
of the cool things about the Cassini
mission is it has several instruments
and each one of those instruments looks
at a different wavelength of light
basically a different color of light
some of which our eyes can't see and
some of those colors help us look
through things so this is this is
actually an infrared image it looks down
into the layers of Saturn's upper
atmosphere and we can then see that the
thing that makes this this hexagon this
pattern of airflow is a jet stream
there's a jet stream at a lower level of
the atmosphere that is causing this
pattern to be set up
is actually kind of like a standing wave
if you've ever had a rope with a have
another friend hold the other side of
the rope like a jump rope or had it
connected to a wall and eventually you
can just get to go up and down up and
down so instead of just doing this the
rope just goes up down up down up down
that's a standing wave the pattern
actually really doesn't change this is a
standing wave
except it's huge and it's six sided and
it's really interesting and also
coincidentally beautiful really cool so
we learn lots of lots about what's going
on with the interior structure of Saturn
this way oh and if you look closely
you'll see this part right in the very
center right at the North Pole this is
what's been called the Rose because it
was cleverly colored in red in this
representational color image and it does
look like a beautiful rose this is a
giant hurricane right at the North Pole
and this has told us a lot about how
giant planet atmospheres might work
because we're not just again remember I
said that different wavelengths of light
could probe different levels of
atmosphere that means we can see
vertical structures being able to see
how tall a storm is is really important
to understanding how it forms how it
works the dynamics of it um have you
guys ever been out on a summer day and
you see a thunderstorm forming in the
distance and you see that the clouds
billow up and it forms kind of an anvil
shape you and then you say oh I better
get inside or I better drive home from
work right now because that's gonna be a
huge thunderstorm and I know what's
gonna rain and I know there's gonna be
thunder and lightning I better get home
that's the same kind of thing that we're
learning about here those verticals that
vertical structure is really important
to informing us how this works another
example of the amazing storms we've seen
on Saturn is this guy right here
hi Messi it's starting to form over here
this is regular quiet Saturn nothing too
exciting happening like I mentioned
before you know no no huge bands
typically an in regular visible light
Saturn looks kind of yellow kind of
orange nothing big and bold happening
and then we see a storm form and slowly
that storm creates awake as different
layers of the atmosphere move around it
and you can see this time series where
then it keeps going along into a long
band and it wraps itself all the way
around Saturn and eventually you have a
very interesting curly fringed band so
that's telling us we've learned a lot
does this happened over the course of
several months and this thing lasted a
couple years I think and so through this
we were able to really learn about how
storms form how they persist what may be
causing them to to die out and quiet
down so this also tells us about stuff
on our own planet right we know about
hurricanes hurricanes exist on earth and
when you're over the ocean especially
when it's warm you have the the moisture
you have the heat that hurricane can
build up and build up and build up and
get really strong but the second it hits
land you lose the moisture and it may
die out the second it hits goes too far
north and it hits some cold water it may
die out so what a storm that persist is
telling us is what's going on underneath
what is giving the storm its power what
is driving that storm so learning about
how these work on Saturn really tells us
a lot about how these work elsewhere for
example Jupiter so toward the end of the
Cassini mission we have the fantastic
sibling the sibling spacecraft that goes
out to Jupiter called the Juno mission
and Juno mission has Juno cam
which is actually a public outreach
instrument was not intended for science
but we're seeing some amazing images
come back from it that we're doing some
science with you can compare this sort
of storm on Jupiter you can see some
vertical structure there are some other
interesting things too what we seen on
Saturn or you can look at things like
this this is Neptune every image I can
see in the first like three pages of a
Google search on Neptune images is this
image or some version of it it has this
big storm here and I know Frank's talked
about this storm before I think in the
news from the universe or something
before the public lecture series that
storm doesn't exist anymore
it hasn't existed for years and we know
this but this is such an interesting
image that this is the Neptune image
that everybody associates with it
this storm probably only lasted a few
years but Neptune is different then say
Jupiter Neptune is farther out from the
Sun so it's cooler it's made of
different stuff like there's ammonia and
some other like no it's not hydrogen
helium like like Jupiter and Saturn lots
of other things going on in the
atmosphere so what we're learning is by
looking at just the four examples in our
solar system how the spears are
different there's no cookie cutter
formula for how these things work and
now that we have thousands of candidates
of exoplanets many of which are gas
giants of some sort we can now start to
put the pieces together and learn more
about how these things work
and not expect as scientists who model
these things can't expect them all to
work the same way especially when
they're in different circumstances say
you have a gas giant that's off that's a
hot Jupiter who's here heard of a hot
Jupiter that's something roughly Jupiter
sized that's really close into the star
closer than mercury is to our Sun so
it's really hot right they're so hot in
fact that you know the the atmosphere
could bubble away
evaporate away from the heat of the Sun
it's so close that it's tidally locked
that means there's one side that's
always daytime one side that's always
nighttime it could it could be really
far far far far far far far away and be
very very cold it's still really big
what happens there we we need to answer
cities and so studying staying that what
I call our backyard laboratory versus
that solar system is really important
because now we have all these candidates
we want to know what's going on with
them we want to know how these work we
also are finding out compositional
information every day the Webb telescope
is going to tell us what these
atmospheres are made of and we need what
we call ground truth the Cassini mission
has given us some ground truth some some
really concrete evidence nearby of
something that we know of that we have
observed for a long time and we we can
compare to I turn them all use later and
throughout this talk is comparative
planetology so that's really important
for what we're doing and what the
Cassini mission has contributed okay Oh
into planetary wings
you saw that I talked a lot about
atmospheres wait till you get me started
on the planetary rings I love planetary
rings that's my background I'm all about
the Rings so for Saturn itself we
weren't really sure about the Rings when
we got there
we've seen some cool stuff with Voyager
we've seen some cool stuff from the
ground but we weren't really sure what
we've learned is the ring rings are
ancient they've probably formed with
Saturn they're massive they're probably
you know a fractional size of a moon
which is way bigger than we thought they
were going to be they have all kinds of
complex structures inside including
small moons that we call moonlets they
have they change on small timescales
human timescales Cassini life time
schedules which is unheard of for
astronomical objects you know we're not
dealing with millions and billions of
years for a change
talking about weeks months I went to did
a paper where I measured how things
changed over the course of 28 days what
you know you know grass and my the the
grass in my yard at home grows on the
same time scales that some of these
things happen thank goodness I don't
have to mow the Rings okay it also
changed our view of our solar system
Ksenia our Saturn is not the only planet
with rings Jupiter Uranus and Neptune
also have rings they're different but
now we know the ring systems are not
necessarily temporary this makes sense
because we see them around all four of
the large planets in our solar system so
it clicks and these rings are constantly
evolving again helping us piece together
the puzzles for these rings especially
on Uranus and Neptune that we haven't
gotten a really good look at we've only
gotten some some Voyager data back from
them so we really want to know more and
finally told us about other solar
systems so I'm not talking about the
ring systems in other solar systems I'm
talking about the disks that surround
those other Suns that planets are born
from the rings are an excellent example
of an Astrophysical disc and another
example of an Astrophysical disc is a
protoplanetary disc the the gas and dust
and debris that forms new planets and by
looking at Saturn and the Rings and how
moons form in those rings we can learn
about how complex worlds are built in
the debris disks around new stars okay
let's set the context again broad dense
rings the classical rings ABC the gaps
within those classical rings and then
the
huge dusty component which encompasses
the e the G in the Phoebe ring alright
and what are Saturn's rings made of they
are made of water ice so for those of
you from Philadelphia I apologize it's
not some delicious treat when I say
water ice I'm talking about h2o so this
is actual ice that is in all kinds of
sizes so it's huge distribution from
from dust sized grains of ice all the
way up to things the size of cars and
houses we have these things are
constantly moving smashing into each
other sticking and then those things are
hitting each other and pulling each
other apart this is a constant swirl of
activity and what the Cassini mission
has really shown us is how dynamic these
rings are that this process of Smashing
and accretion and destruction is
constantly happening okay so what we're
really learning is that the Saturn
system is not a ring system it is a ring
moon system and these rings and moons
are constantly doing a dance
there are 62 named moons but I like to
say that there are billions and billions
of moons at Saturn because each one of
those little particles in the Rings is a
moon they're all orbiting Saturn
together in this beautiful dance so
let's zoom in into the outer be ring
edge and we see vertical structure the
Cassini mission was there for equinox
equinoxes when the tilt of the Rings
perfectly lines up with the the plane of
our solar system so that the Sun is
perfectly on edge and there's no so that
means that it casts shadows anything
sticking up from that flat playing of
the Rings
is gonna cast a shadow this really
helped us because we saw at the outer
edge of the B ring
we saw mountains these are all mountains
and it's not an even distribution it's
really really kind of a funky look in no
symmetry these are I said these are
mountains these are thousands of feet
tall and we see those those those cool
shadows coming out from him so we know
what how tall they actually are so then
it comes down to the dynamicists and we
dynamicists looked at this and we've
tracked out where other moons were we
tried to figure out what was causing
this and we said that's no moon well
actually it is it's called - or Mimas
people say it both ways and this is a
moon that's just outside of the
classical rings that's where it's orbit
is and it picks on the ring particles it
tugs on them just a little bit with its
gravity tug tug tug and just like you
might have a tub of water and when you
move it back and forth it actually
sloshes so that stuff comes up the waves
come up out of the tub
that's what's happening here so we have
vertical structure because of the
sloshing that - causes so this causes
vertical but if you were to look down on
a vertical you'd really just see a
density enhancement so you'd see a big
clump of stuff it's very thick there and
when we look at other solar systems
other forming solar system we see a disc
around a star so this is where that star
would be this is the whole disc and you
can see that's not a pretty uniform disc
there are bright spots here kind of over
here and empty spots up here that looks
surprisingly like the kinds of weird
structures we see at the B rings edge so
a ring scientists use that and says oh
there's a planet there there's a planet
so what we can learn from rings applies
to protoplanetary
disks to debris disks that sort of thing
just for comparison this is this is
really big this here would be Pluto's
orbit in our solar system so you can you
can match how big this disc really is I
mean the dynamicists can map that and
figure out where to look for the planet
in this system okay so let's go back to
Saturn's rings for another example out
to the the airing the airing is where we
see these gaps and we knew about this
before Cassini we knew there were two
gaps in the a ring there was the inky
gap and the Keeler gap and inky gap was
was a was big enough to really see you
pretty well the Keeler gap was very thin
with the inky gap we saw a moon we
called that pan and we saw it I mean we
didn't know what Pam looked like till we
got there but basically it's a sad
twisted little potato you know maybe
maybe the size of Manhattan Island
something like that but we only saw the
Keeler gap we didn't see anything inside
of it so we thought well what else could
cleared this whole gap there must be a
moon there so Cassini looks for it and
Cassini found it in this gap this Keeler
gap that is only about 40 kilometers
wide we were able to find it even
smaller even sadder even more twisted
and rotten potato and so we gave it the
lovely name Daphna s-- and we learned
something else because the Keeler gap is
so small you can see
Daphna spilling on the edges of it oh
you could see it kind of here and this
structure again it's the same kind of
structure that happened in the outer B
ring that vertical structure there's
there's a wave or a wake kind of like if
you think of a boat going through water
something very similar is happening
there same kind of mechanics over in the
with pan that it disturbs in the inky
gap and
so we know this is this kind of thing
happens moons form within the Rings and
they can clear large swathes of the
Rings so again let's take that out to
our galaxy let's take that to other
stars because we see debris disks
everywhere and when we see a debris disc
like we did here with Hubble we see a
big gap around this particular star in
its disk again a ring this person says
oh there's a planet there there's a
planet there I know it so you do
something this is this an illustration
of what could be happening here the same
kind of ring exists so now we have we
have a place to target our observations
a mission like the like the James Webb
Space Telescope will be able to do a
good job of looking for a planet in
there if it's big enough because the the
dust and the gas and the debris disk
will will the infrared light of the star
may be able to pierce through it so it
plus it has a coronagraph that'll block
out the star so we might be able to see
it that way
plus there's all kinds of other like I
said before other systems in our solar
system
there's Uranus and Neptune here very
thin very dark rings but they can teach
us something as well and the lessons
learned at Saturn with Cassini can be
applied here to learn what's going on we
think that there are moons being created
in the ring system of Uranus we've seen
rings change since voyager in at Neptune
so we know things are happening that
these are dynamic rings as well so we're
people who worked on the Cassini mission
are now turning their attention to
Uranus and Neptune especially using
Hubble and putting in proposals for the
James Webb Space Telescope to be able to
study what's happening
systems our solar system itself has two
Astrophysical discs we have the asteroid
belt which is here between Mars and
Jupiter when we have the Kuiper belt
which is out beyond the orbit of Neptune
kind of where Pluto sets and both of
those are remnants of our solar system
of the formation of our solar system and
by looking at those by studying those we
can tell what happened in the formation
of our solar system and learning about
the dynamics of health of the Saturn
system applying that to the our solar
system and what it looks like now we can
start to put the piece the puzzle pieces
together
for example there's an interesting
dynamical thing that probably happened
in the asteroid belt a resonance that is
evidence that the four giant planets
used to be closer in together and that
they jiggled out separated and while
they were doing that Uranus and Neptune
probably swapped spots so tracing out
the dynamics of these kinds of
Astrophysical discs is really important
for us understanding our own solar
system and as I mentioned before we know
of all these debris disks protoplanetary
discs across our galaxy that we can
apply lessons learned to to be able to
learn how planets are forming target
where to find them in the disk and we
have all these new telescopes coming up
including the James Webb where we'll be
able to look into these dusty discs
using infrared all right so really this
and this is my mantra Saturn's rings are
a natural lab we must go back we've
learned so much already and we can learn
more okay and finally the Third Point
icy moons of the big discoveries so big
the icy moons we knew about but we
didn't know
until we got there that Enceladus has
plumes meaning geysers something like
Old Faithful which we like to call cold
faithful by the way Titan has lakes this
big earth-like moon has lakes liquid
lakes we didn't know that before we got
to Saturday before Cassini got to Saturn
so then we changed our view of our solar
system because we learnt we realized icy
moons can be geologically active we
didn't think that was possible we
thought icy moons were just hunks of ice
left over from maybe the formation of
the planet itself or maybe they were
captured from the Kuiper belt or you
know some some kind of loan comet that
got trapped but no this is really
interesting and then when we apply to
other solar systems we realized
geologically active moons could Harbor
life they could be warm enough that
we're getting the right environmental
conditions for life to exist on them and
this expands our whole view of what
habitability means of what a habitable
world is expanding those definitions is
huge because astrobiology is a
burgeoning field even today and we're
learning new things every day which
Cassini has really helped to point to so
again setting the context all kinds of
moons going out from the Rings even more
farther out that we don't have room for
on this screen but let's start with
Titan so Titan is the biggest moon of
Saturn system Titan at first glance and
visible lights just looks fuzzy and
orange that's because it has this big
thick atmosphere really big and thick as
a matter of fact in in one of the the
more recent Star Trek movies the the
enterprise hid inside of those that hazy
atmosphere because it's so good at
hiding things in
wavelengths but once you get inside and
look at it underneath those layers both
with the instruments that were on
Cassini and with the lander that went
down called the Huygens probe we could
see the actual surface of Titan and we
were able to make out methane lakes
these if you look carefully you study
other close-up photos you realize that
there are shorelines you realize that
this is actually liquid standing liquid
and you check out the chemistry of the
moon and you see that it's methane so
just like our earth has a water cycle
where we have water on the ground he
gets heated up becomes clouds rains back
down steeps into the ground and two
aquifers and then comes back up into
lakes that kind of cycle Titan has
something similar but for methane what a
bizarre and cool world and as a result
it makes it the most earth-like thing in
our solar system besides Earth this is
fantastic but it's also very cold so I
don't know that it's the best candidate
for habitability but it is stretching
our thinking on what habitability is
even if it's cold it does have this
liquid liquid on the surface it has
lakes it has it has dunes it has sand
dunes now some of its it's it's tiny
pieces of ice rather than rocky you type
of sand that we have on earth but Wow it
has winds it has weather it rains
liquid methane again but this is really
fascinating so we have a complex world
here that we're looking at then a little
bit later in the mission I actually got
to be part of this one so I'm really
excited
about this story uh we were working with
a team the team that does the imaging of
course the imaging team reaps all the
benefits on Cassini the beautiful images
everybody loves the imaging science
subsystem but they see something around
and sell it us and they think that can't
be right
there's got to be something wrong with
the detector we had some kind of anomaly
in the feed that came back to earth
we're not sure but I was lucky enough to
be on the the Uvas team the ultraviolet
imaging spectrograph team so we were
like okay well we took some images to
let their not images but we took data
let us look at it
let me see there's evidence that there's
something right around here theme for
red instrument does the same the radio
science instrument does the same and we
all confirm that this whatever it was
right here is there I wasn't just
something weird that imaging picked up
so we go to work on it we realized that
it's a plume it's a series of geysers
that are erupting out of the South Pole
of Enceladus now Enceladus by all
accounts is yes it is the brightest
thing in our solar system because it's
covered in pure white ice but it's it's
small it's only like 250 kilometers
across that that ice looks to be really
really thick why would it have geologic
activity that would cause a geyser but
we've done studies we've we flown with
Cassini flew by and sell it as many many
many times and we mapped it out these
geysers were there these geysers changed
position over the course of the Cassini
mission they gave us evidence that
there's possibly liquid under the
surface and that these icy worlds that
seemed geologically dead are really
interesting and active
we had hinted at this before we weren't
quite sure when we got there we we saw
Enceladus buried in the earring embedded
in the earring and we thought well maybe
that's why it's so bright it's in a ring
of ice and it gets the ice dropped on it
every day and that's what happens but
now we realize that ring is there
because the plumes feed it it is created
by Enceladus itself Enceladus is spewing
out all the contents of that ring so
that gives us a new a new outlook on how
rings are created okay I mean like I
said it's probably you know we got some
really close-up images after that all
these various geysers happening all the
time they you know I don't know who's
who seen act actually seen Old Faithful
in in real life okay you know it goes up
maybe a couple hundred feet at this
highest point this however goes up
kilometres you know it goes out almost
as tall as Enceladus is wide so that's
how it feeds the e-ring it's it's a
phenomenal and we realize tracing back
the dynamics of how that must work that
there must be underneath this thick ice
shell of Enceladus some sort of
hemispheric sized lake of liquid water
that's feeding it and it stays warm so
then we start look we think oh well that
one's active let's look around the solar
system people have four years loved
Europa around Jupiter and we've thought
oh you OPA could have subsurface
activity we think that there has a thin
ice shell based on on gravitational data
from the Galileo spacecraft we think
that it probably has a subsurface ocean
let's look at it see if it has any
geysers so Hubble looked at it and BAM
sure enough we see evidence for water in
certain areas at certain points of its
orbit which means it probably has some
kind of period
geyser it's coming out of again its
South Pole now we're not sure on the
South Pole connection but that's
interesting and so you get something
that's kind of like this artist's
impression what it might be like to
stand on the surface of Europa a guys
are coming out of an ice field kind of
feels like you're in Iceland it's very
cool and you know the alternative is you
could trap a little little under under
crust Lakes full of this stuff there's
the crux of it is there is heat below
the ice heat means energy liquid water
increases the potential for life to
exist so if there's energy and liquid
water perhaps there's life and as we're
thinking about our definition of what
earth 2.0 might look like what another
earth might look like perhaps we should
be expanding our definition maybe it
shouldn't just be a planet that is the
size of Earth that's one AU from a Sun
it's a g2 type star maybe we should
start thinking about ice worlds and
moons around giant planets and those
sorts of things so as we look across our
solar system and as we look at other
exoplanets we need to have this in mind
so we now Cassini has given us this
great gift of expanding our vocabulary
- what habitable means so I promised you
a timeline I'm just to put this all in
context again we had almost 20 years ago
to the day in two weeks it'll be 20
years ago the launch of the Cassini
mission Cassini and Huygens together and
there were five known exoplanets so
Cassini was truly just a Saturn mission
it was there to learn more about Saturn
as a planet then when in July 2004 when
Cassini got to Saturn and did its
orbital insertion there were 12 EXO plan
well I remember that feeling of oh this
is about to happen this is so exciting
but Cassini is still just a Saturn
mission but it will be really cool if we
learn about like 15 or 20 exoplanets and
then in between 2004 and today we've had
the Kepler mission we've had Hubble
looking at stuff we've had lots of
ground-based campaigns looking for other
worlds and so today we know of over
3,600 exoplanets with so many more
planned to be observed those are on
small patches of the sky we know more
exists when you look up in the sky at
night you know that for every star you
see out there on average there's at
least one planet around that star and so
now we can apply these lessons we've
learned over the course of the Cassini
mission to all of those worlds
especially since some of those systems
have more than one planet so we're
looking at at you know ecosystems whole
solar systems that are forming in much
the same way that perhaps the Saturn
system did and we can apply those
lessons to figure out how how these
worlds form and like I said you know we
we know of even more protoplanetary
discs these discs where planets form so
getting back to that first slide so
these icy moons we've learned are
geologically active with the Cassini
mission and this has given us the idea
that they are bastions for life we need
to start looking there if we want to
find life beyond Earth we have seen
planetary rings that are ancient
they probably formed with the planet
they are active on short short
timescales and they are dynamic they're
constantly changing these are a model
for how worlds are both built and
destroyed in our system and beyond and
the weather the storms the incredible
complexity of Saturn's atmosphere has
helped us understand that the
atmospheres of other giant planets are
just as complex and dynamic and we can't
have one computer modeling code that we
use as scientists to model all of those
worlds beyond our own so really what it
comes down to with the Cassini mission
is using our own natural laboratory in
our backyard for answering questions
that are fundamental to us as human
beings how did we get here looking at
the Rings
how does the universe work looking at
things like storms on Saturn and are we
alone looking at icy worlds beyond our
own so I think that the legacy of the
Cassini mission will be felt for years
and years
there are many research projects that
have yet to be done with the data
Cassini collected and many that have
results that have yet to be fully felt
and impacted in other branches of
astronomy so I think as we go forward
together as humans and as a scientific
community we can really come back to the
Cassini mission and thank it for
everything
it gave us
so there's a where does the water come
from
so I do a little bit of history before
we got there with Kasim we thought that
the reasons were likely delivered by
comments comments we know they were
probably streaking by these out of the
system
Chad was big enough that they got close
enough rip it apart
and voila you've got a buddy ring
particle there were different people's
baby how what things once the coments
must there've been to create such
vibrant rings and if this goes true and
these would still have hadn't been
pretty like rings less massive then they
would have over time dating to those
little ring particles spiral into Saturn
I told that tire read was depleted in
there wasn't worried and timescale on
that was something around 50 to 100
million years so roughly the age of the
dinosaurs well why then are we lucky
enough as human beings on a planet in
the Solar System is last billions of
years why are we lucky enough to be able
to see this now yeah but there's one is
for the ancients we got there and so now
we see that they are not quite agent
ancient both spectroscopically and by
the dynamic we see we see them
effectively recycle so things moons
build up and they break apart
so rather than all these particles
spiraling inward because they're
constantly particles they come together
and there's kind of like a reservoir of
ice which then you smash back our
process for keeps
so with the Saturn itself so
well then our baby how still our Daniel
planted when you put in that ice water
initiative come from the current most
likes idea is that the initial system so
something similar in size Titan probably
had half a dozen of these and they so
slowly moved in closer to Saturn and
we're overtime ripped apart by PI's and
helped replanted so that makes sense to
carbon so which is assault so so yeah
lots lots of stuff in there I know some
of the stuff that most recently in the
in the plumes that they're they're
finding are in that plume besides water
they're finding exists in what what are
under see underwater events
earth these deep ocean vents where we
see lots of life very small bacteria all
the way to like little blind crayfish
and that kind of thing so finding
evidence of those sorts of materials in
the plume lets us know where the plumes
may be coming from ultimately and that's
really exciting and and I think carbon
carbon is is one of those that would
give us evidence of them happening
farther down deep down and the kinds of
materials that are at those undersea
vents other questions does the shape
ever change not that we've seen so far
in all of our observations
we haven't seen a change over we there
was some evidence of the hexagon being
there prior to the Cassini mission both
ground based absorb servation and
voyager famous a kind of a skewed view
and what we thought might be the hexagon
so we thought it was there which now
builds up evidence of you know something
more like 40 years of it being there and
our resolution wasn't good enough to
know that was there so yeah so we think
it's it's very long-lived and we haven't
seen any
okay over here
yes the like the storms great storms
move around we see them actually move
question about the end of the Cassini
mission how deep did it get before it
burned up and did we get some useful
data but unfortunately because of how I
was going in we tried to position it so
that would send back data but there
wasn't much time for that the data that
comes back from my exceeded mission as a
men in deep space missions you'll recall
New Horizons was this way to very very
slow trickle of data so that's why we
first saw Pluto with New Horizons and
still rainy and fuzzy and he had to wait
a couple of weeks
that wasn't just data processing that
was actually getting the data to earth
the interplanetary Internet is like your
the Hurricanes are short-lived it's the
polar hurricane short-lived who does
that affect the hexagon shape extra cold
winter but I'm not that I will say I've
done hundreds ensures I'm not an expert
there's a theory that you robos water is
liquid it's because of the interaction
between it and Jupiter the gravitational
pull of Cooper if that is also true
between Saturday and so Enceladus is
it's water due to gravitational
interactions with Saturn the interact
the gravitational interaction being kind
of a title compression that happens same
way we have tides on something similar
happens with Jupiter it's way better and
its movements which are a little bit
smaller so effectively squeezes those
moons and that squeezing that has energy
to this and that
because these are so are we really that
fortunate and if you look at robot Wow
to be living in a time where both of
those are active and this or maybe the
the actual situation is that this
activity is just ongoing it always
happens and we're not special so sorry
scientists tend to think we're not
special
hexagons image and about ourselves with
a fuzzy white dot and about nine o'clock
with a funny little miniature spacecraft
actually
what the hexagon image about four
o'clock there's there's some kind of let
me just slide back at four o'clock there
is there we go
yeah okay at four o'clock there's this
thing I don't know that's five o'clock
there's this kind of blobby thing and
then over here at nine o'clock there's
this thing what's going on
well this is this this is definitely
some sort of other storm and disturbance
that's happening within this structure
this isn't a you know this is a shape
but this isn't the shape here this
definition of the shape doesn't control
what's happening in here it's it's like
a wall and it can find some of the
things inside of that wall but it
doesn't necessarily make things happen
in that wall so so this this storm this
is a storm it may not be related to the
hexagonal and this I don't I don't know
that maybe that's I don't know maybe
that's an artifact I have no idea
well we don't want this crap no it's
clean clean by our standards from when
we don't want to accidentally smack it
into one of these moons for similar
reasons so this is this is a
long-standing practice just kidding
we are yes you mentioned in your
presentation that hurricanes feed on
heat this is anymore
they sing hurricane what is the energy
source okay so her needs for you don't
heat what's the energy source to power
the polar vortex here so just because
it's it's northern facing doesn't mean
that it was facing away from the Sun
that's that's the first one but Saturday
the self is what an internal heat that's
all the giant planets had a lot of
internal there they're far away from the
Sun it really doesn't matter how much
they're warmed by the Sun
but for this particular thing that was
more than that the internal team is
there Saturday is actually super
interesting when it's internal it
produces a lot of it because it's very
dense lots of gas layers and as
something that big eventually kind of
settles out the different gas layers
settle out or over the lifetime of the
planet
some of the the heavier elements that
are in the outer layers settle down so
basically what can happen at Saturn is
you could have liquid helium rain into
the inner layers of Saturn and that is
energy those things falling when we look
at Jupiter for example that's another
example
Jupiter's output of energy is greater
than its input the energy absorbs from
the Sun is less than what we see
radiating back for the same reason okay
we've got time for only one more
question
this guy in green here's been waiting
the whole time to get the honor of the
last question sorry mind if I the
interesting Expo biology and I'm just
wondering what are the odds for life on
the news and and are we going to send
something specific specifically to look
at those moons for life
good question end with yeah I would rank
the moons of the solar system in terms
of probability of life as Europa and
sell it as tighten your rope up because
it probably has the most heat the
shallowest crust and the the largest
rocky core that could support some sort
of chemoautotrophs type organism at a
and a deep-sea vents for example but I
can't put numbers on probability for
that the way to confirm this would be to
actually go there with a submarine
that's what I would like maybe something
that could land drill down but you know
even an orbiter or something would be
very cool the problem with that is the
Jupiter system full of radiation you
have to do with the Juno mission does
come in quickly and go way far out come
in quickly and go far out or else your
electronics are fried so this is one of
the tough things about a Europa mission
which makes which makes the Saturn
system a little more enticing less
radiation there but I think in the
community's opinion maybe less likely to
find the life so what we can keep doing
is we can keep compiling evidence as
scientists we we want evidence and
there's never necessarily a smoking gun
unless we were to go there and pick up a
whale you know so
that was got one strong mission yeah
yeah but I would just echo I would echo
what she said is that you know when we
explored Mars we first sent an orbiter
alright and then we started to send it
to send Landers and then Rovers etc it's
kind of if we're gonna explore any of
these moons it's got to be the same
thing we've got to send orbiters to map
all the places that we might want to
land and then Landers and then Rovers
and then diggers and submarines and such
so it's not gonna happen next year it's
not gonna happen this decade it's a
long-term process all right so we have
to stop you there next month's talk will
be on dangerous worlds so we'll take
this even further lazy now let's give a
real big warm hell thank you for dr.
Bonnie my team
okay last thing ireenie
a rainy rate raised your hand Irene II
can take what 15 people okay I know
there's way too many than more than 15
but when you have enough just go do you
want to hang hang out by this store okay
Irene ease gonna hang by this store when
she has enough she'll take them across
the street for observing and if you
don't make it this month come back again
she'll do it every every month it says
clear thank you all and see you in
November
