i'd like to welcome everybody to
nasa's guided space flight center
we're holding this uh special briefing
today to discuss the largest fragment of
comet shoemaker levy to strike jupiter
so far
that fragment fragment g
struck the planet early this morning and
has produced some pretty exciting uh
results
with us here are gene shoemaker
co-discoverer of the comet
and
with him heidi hamill of mit
gene
thanks mike
we're really here to hear from heidi
who's got some spectacular stuff to show
you
i should just remind you that heidi is
the principal investigator the leader of
the imaging team
on hubble for these observations so
she's re reporting for
for the team for these very exciting
results
thanks gene
it was just 12 hours ago that g hit
so we've been working very hard in the
last half day to be to be able to bring
you these images
and i'm sure that in a few days we'll
have a lot more to show you right now we
just have black and white pictures no
color just hang on
so i'll just uh cut straight to it and
show you some of the images we were
lucky enough to be observing right when
this thing happened
we have one image before the sequence
which shows nothing then you can see a
tiny tip of the fireball
and just a few minutes later five
minutes later the the plume is growing
three minutes later it's grown even
larger
three minutes after that it seems to
have stabilized reached peak altitude
but started to spread and then we have a
seven minute gap and you can see that
it's completely flattened out into that
pancake again we have about
three or four more images all showing
that that flat pancake just hanging in
there and then we start to see it rotate
onto the disc
we then an hour and a half later took a
series of images with this impact site
rotated onto the disk and i'd like to
show you that particular view right now
we were using the planetary camera and
we can't fit the whole image of jupiter
in the planetary camera because it's
very high resolution camera you can
clearly see the impact site
now
remember a few days ago i showed you a
picture with a box and i said the box
was the size two earth diameters let me
give you a sense of scale here
you can see a little bright ring and if
you could keep the graphic up so people
can see it at the other places
there's a bright spot and there's a
little dark ring you can see around the
spot and then you see a larger sort of
smudge to the south
that little dark ring is 80 percent of
the size of the earth
that large ring that big smudge you
could easily fit the earth inside that
diameter
this is one big impact site
it looks a little oval because we're
very far south and we're also close to
the edge of jupiter so you have an
interesting projection effect let me
show you a blow up of that this is a
blow up in the green wavelength and then
you can see more clearly that ring i was
talking about now when we project that
out as to what it would look like if we
were looking straight on that ring is
perfectly circular
and so is that larger white ring around
it
you see that little spot to the side
that's the d impact site
that went in a little a couple days
earlier and so g just barely missed
hitting d and i'll get back to that
effect later on
um
what something very interesting that you
might be able to see in these graphics
is that
as before there's sort of a streak
there's the center of the ring and then
a smudge off to the side very black sort
of thing if you look very carefully now
in that smudge around to the south
you might see rays
you see those rays
okay if you look very carefully you will
notice that those rays do not appear to
point to the center of the ring
they appear to a point they appear to
point towards where that smudge
intersects the ring
that's very interesting
let's show the next image this is a
green image the following image you see
is the methane band image which i've
shown you before remember i talked about
green visual wavelengths it's dark in
the methane band image it's bright and
there you can see this even more clearly
you see those rays that are emanating
from that intersection of the bright
ring and that central streak
we don't know quite what this means yet
but but i have a theory and and i'm sure
everybody has theories but since i'm
here in front of you i'll tell you my
theory and then gene can tell you his
theory uh my theory is this that the the
lower southern portion of that streak
is the impact site itself
and that what happens is this thing
streaks in there keep the graphic up so
people can visualize what i'm saying
here either either color
it's it goes into the lower part and
streaks down into the atmosphere and at
some point it explodes and that cir that
bright circular ring is centered on the
impact site
right then the fireball
comes
portions of the fireball move back out
the impact site and spew out when they
get to the to the top to the hole and
that's why those rays are centered on
the end and not on the center of the
ring
now remind you this is just my theory
and i'm not a theorist i'm an
observational astronomer but that's what
the observations sure look like to me
now the question is why is that whole
streak bright
and that could very well be that that
whole tube is just very very very hot
and it's ionized and
and gene might tell you later that that
all of it's rising but that some of it
spews out the end there
so so that's my that's my personal
theory about what that image shows but
we're going to have to do a lot of work
before we can say for sure that's what's
really happening
um
the
the energy of this event
was probably about 25 times larger than
that first impact we showed you and that
jives very well with the sizes of these
things this is a much larger splotch on
jupiter
and very likely this splotch will be
spreading out as the days go by one
interesting thing that i don't have a
graphic to show you but i'll share with
you is in one of our wavelengths
we can tell that this material is very
very thin this big that big brown smudge
the the black eye on jupiter as it were
that smudge is very thin because we can
see the bands of jupiter right through
it
it's just laying right over top of that
so
i think that's about all i have to say
right now we're going to be working very
hard over the next few days to analyze
these data and i should add that we are
not the only observatory in the world
watching this many observatories around
the country have been focused on this
and are reporting very exciting results
in the infrared they've been studying
that plume in the infrared they're
seeing the spot in the infrared
all over the world people are tracking
this
okay thanks heidi
uh i wonder if you want to mention
uh the actual height the maximum height
that we see above the limb there i don't
think you may that's a good thing to
mention um in that plume when we saw
where it peaked out at some level
that we looks like we are seeing that
about 2 200 kilometers above the limb of
jupiter and i'll remind you that the
impact sequence we showed a few whenever
it was yesterday um there you go that
only
got about a little over a thousand
kilometers so this is a factor of two
higher okay great
uh i'd like to make a uh
heidi mentioned the energies
and we sort of had a top of the
head estimate of the energy this morning
which i hadn't had a chance to actually
calculate out i like to make a
correction for everybody
because we were multiplying by the wrong
number to begin with it doesn't change
our estimates of the sizes of the
objects
or the energy in ergs but it is a change
if you want to put it into megatons so
our best estimate or my best estimate
for the energy for g
uh is not the 250 million megatons we
mentioned this morning but it's six
6 million
megatons that's still a lot of megatons
but please make that correction and
correspondingly for
for a the real number should be about
225 000 megatons that's still a lot of
megatons uh but those uh that's just
just a slip uh in in the ballpark
estimate i made earlier so please
correct
uh those numbers if you will
mike we'll turn it back to you okay
we'll take questions now and uh later
see if there are questions from any
other nasa centers uh please wait for
the mic and state your name and
affiliation please
bob cook newsday you mentioned there
might be so you're going to talk
something about the interaction between
g and d perhaps that's great um actually
that was a teaser so someone asked me
this question because i have something
that i want to talk about that's even
more exciting and that is some of you
have heard about the q impact q used to
be the brightest one before g took over
and for a lot when we were doing our
planning sequences early on we were
planning on q as our primary target not
g
well
when q goes in and i don't remember the
time the date some sometime tomorrow or
the next day
a very interesting thing is going to
happen
q is going to go in and exactly one
jovian rotation later 10 hours
r is going to hit right next to the very
same longitude as q
and one jovian rotation after that s is
going to hit the same longitude on
jupiter
so you're going to have three boom boom
boom right on the very
very small range of longitude
and that is going to make one heck of a
mess
well we're really looking forward to
that that's the um
well not messes but we're looking
forward to some really interesting
chemistry because what that means is you
know you're not just taking the
atmosphere and stirring it up a little
bit you're really stirring the
atmosphere up a lot so that that'll be
very interesting and that's that's why i
mentioned those the proximity of those
two impact sites
bill
uh bill hart with cbs for two quick was
one the the very clearly defined ring
around the central thing
great question awfully sharply defined
and the other one is if you can see the
cloud bands below the smudge you're
seeing through it i suppose
is there no wind at all at the altitude
these things are would you expect that
to change pretty rapidly if it's that
thin
all right great question that ring
there are some theorists who would love
to believe that that ring is an
atmospheric wave
it's too small to be a seismic wave but
it could be one of these atmospheric
waves that many theorists have been been
predicting andy ingersoll and tim
dowling and joe harrington
they would love to believe that now
if that ring expands then we'll believe
it's a wave if that ring does not expand
with time i'm talking about if it does
not expand with time then we have to go
back to the drawing board
we're waiting to get the next sequence
of images down so that we see what
happens to that ring
so it may be a wave it may not time will
tell
the other question was about the wind
speed this image was only taken an hour
and a half after the impact so in an
hour and a half the winds aren't strong
enough to perturb it on the scales that
we're seeing here
certainly over the next few days we will
be watching all that material
very closely to see how the winds
distribute it and it will be distributed
there's no question
how do you want to mention that it looks
as though some of the material in the
spot from the a impact is being smeared
out that's a good point gene yeah it
does look like that in some of our
recent images the the a impact site is
not as crisp and sharp as it once was it
looks kind of
messy so as that material gets followed
in fact it will be a very nice tracer
for the velocities of these upper
atmosphere winds for which there
actually is no previous information so
very important information about jupiter
will come up from that
take a question over here yeah i have
two questions one can you estimate the
distance between
that d impact site and the new one the g
one and also this morning john clark
showed us uv um
images that show that these impact sites
when imaging the uv are much bigger than
they are visually
you suspect the same is true of this and
that it is in fact even larger the area
of disturbances in
uv
well i'll answer the second part first
we'll wait and see when we get some uv
images for sure it sure looks like that
from the other three impact sites so
probably yes probably it will be larger
in the uv
and
what was the first question what's the
what's the separation yeah can we do
that yes we can have we done it not yet
we'll get to it
maybe they've done it already by the
time i was coming out here
we'll take a question back here
uh hi john rutherford with nbc can you
talk about the uh what kind of impact
this would have on earth if these things
were hitting earth instead of jupiter
well i i told gene i'd get them up here
to answer that question well let me just
point out again the scale remember that
the earth is
you know about the size of that ring you
saw all right
so the the scale the physical scale of
this effect
is terrestrial
it's that big
you know i i i wouldn't want to be on
earth if one of these pieces landed on
earth
if you were going to ask what's the size
crater this would made on on the earth
if we're right about our estimate of the
size and the energy
if it hit
a continent it would make a 60 kilometer
diameter crater there abouts well how
does that compare to the size of a state
for example rhode island oh it's about
40 well it would it would pretty well
the crater would pretty well cover rhode
island yes
uh
the and the other thing is if you look
at the size of of the material that's
actually spread out and remember that's
now gone up very high that would just go
out ballistically all over the earth it
it's enveloped the earth
completely enveloped it's gone all over
the earth so so that the material that's
blown out of that crater
would essentially blanket the earth with
a layer of fine debris that would just
block sunlight you just get dark all
over the earth
right over here
uh this is mark caro the houston
chronicle
regarding the sequence of three
that happened every 12 hours later in
the week could you is it possible to be
a little more descriptive about how
close those would be together and in
some
you said the same latitude but i didn't
know that you meant the same
quarter of the planet or stretched
you know one third of the way around
okay it's every 10 hours it's every
jovian rotation
and
um
i wish i brought the numbers with me
they're very close in longitude
on jupiter all of these are close in
latitude they're all in the same band
around the planet what these are
striking about that group of three
coming up is that they're all close in
longitude and i i can't remember the
number off the top of my head i think it
might be within 10 degrees
certainly all if they have sizes
comparable to say a or
c or e which we've we saw
earlier this morning
all those regions will overlap
okay we've we've got a question right
over here
deborah savarenko at reuters this is a
really elementary question but my
editors have been asking and i haven't
come up with a good response
i need to make clear to our readers the
difference in size between earth and
jupiter how many more times
bigger is jupiter than earth
well i like to put it in terms of the
great red spot the storm you see on
jupiter
you're familiar with the red spot you
could fit two earths there it is you
could fit two earths inside that red
spot
that
how many do you know the number the
diameter is about 12 times greater for
jupiter 12 times 12 earth diameters
roughly
paul
um
yeah paul reese of ap and in the uh
in jupiter's black eye there the pupil
of it there is a white spot uh
i noticed in the earlier earlier
pictures do you have any idea what that
white spot is an artifact or is that uh
i'd have to see the graphic to know
exactly what you're talking about see
that uh
right right above the pupil there i
would guess that's just a cosmic ray we
that's a an instrumental effect in the
detector it's not a real white it's not
a white spot okay i'll look at it we
didn't have time to really clean these
images in the last 10 hours and i want
to make very sure i understand the
comparative sizes here uh in fact this
is this is three concentric rings you
got a dark
um element in the very center then you
got you got a very uh uh nearly perfect
ring around it and then you got the
smudge on the outside the earth is the
size of what exactly of those three okay
i'll give you some numbers to chew on
well can you just compare it to that
yeah well yeah the the
the earth is a little bit larger than
that the black ring the sharp black ring
the earth is a little bit larger than
the sharp black ring but the earth is
smaller than the whole smudge area
okay
on the far end over right over here
uh david chandler from the boston globe
um i know when these images first came
in saturday night you were surprised to
see black smudges rather than white
smudges and i don't know if i've missed
something in between but what's your
best thinking at this point about why
these smudges are black
i think our
the theories are are numerous um
many people
are theorizing that a lot of what we're
seeing is is some commentary material
comets are very dark
and
it also might be material from jupiter
that's deeper down that we're not used
to seeing higher up and that material
could very well be a very different
color
i don't have a very good answer for that
question right now
i think i was surprised because
most of the
most of the fresh features that we see
on these outer planets that i'm aware of
tend to be white and bright and so
that's why i expected them to be that
color and i was very surprised
in the plume picture that you showed
today and as well as on the earlier
plume pictures you see a bright plume
and then there's a dark region before
the limb of the planet
why why is there that dark region great
question there's two reasons there's
there's a dark region there the first is
that we're seeing the crescent
of the shadow of jupiter jupiter is not
fully illuminated okay the sun is a
little bit off to an angle about 10
degrees so there's a little tiny sliver
that's unilluminated just like we see
the moon in the sky has pieces that
aren't always illuminated that's part of
it
but the other part is that these plumes
are so high
that the shadow of jupiter
just a little sliver of the shadow of
jupiter itself
is is illuminating is is preventing the
sunlight from reaching that
and we're doing some calculations right
now to tell you very precise heights of
these things we're working on it right
now but most of that is the
limb of the planet a good way to look is
the bottom image if you could put the
graphic up the bottom image you see the
edge of jupiter and then you see that
smear the pancake that pancake is
sitting on the planet okay that
pancake's not floating in outer space
the pancake is in the atmosphere and
that thin little strip there
that is the that's the
that's the uniluminated part of jupiter
question over here
yes jan smith with fox television in
revising this morning's estimate of the
power of the explosion how do you now
compare it to the size of the world's
bomb arsenal
okay
putting it in megadens i didn't really
change my estimate of the energy i just
made it
error in converting it to megatons and i
guess we have a little disagreement the
number i've always used as the world's
arsenals is 10 000 megatons but there
are other numbers floating around and i
guess the real number is still a state
secret
so i've used what's been commonly used
in some of the literature at ten
thousand megatons so
uh if you compare that with the energy
for new our estimate of nucleus a
nucleus a energy is about 20 times that
now i've heard bandied about just in
this room in the last half hour a much
higher figure for the nuclear arsenal
something like about 80 000 megatons so
then it would only be about a factor of
three higher
when you get to six million megatons
that's a whole lot higher i mean that's
getting in the ballpark of 400 or 500
times the
what i think is the more conventional
published estimate of the world's
nuclear arsenal
okay we've got a question right here
chris leach nhk
what was the the actual size of the
fragment and also what was the the time
that the fragment actually impacted into
jupiter
those are two questions for which we
would very much like to have the answers
to
um
the time betw between uh well the time
of that first image that i showed you
with the tiny tip of the plume was
sticking over that was 7 33
that probably happened that image
probably occurred within say five
minutes of the impact itself i would
guess there's probably only a delay of a
couple of minutes right so so 7 33
minus five minutes somewhere in that
time period is when the impact occurred
and
i can't remember the other question
again
we still don't know the sizes of these
fragments i think if hal were here he'd
probably say that this was three three
kilometer body
i i would say the height of the plume
now
based on the modeling that we've done
for a one kilometer impactor is
consistent with that in other words
you know that that that estimate by hal
weaver for of three kilometers looks
looks pretty golden to me
uh universal time right eastern daylight
time that was uh subtract four hours
early in the morning very early
okay can we take a question in the far
corner and the back there please
jim reston for esquire i have two
questions if you could see the full
plume without the shadow
would it mimic
the
fireball of hiroshima
we don't think so
no what happens in this case is that
the plume is erupting from substantial
depth
uh and so there is a column that goes
down below the cloud tops that you don't
see but what we see at the surface is
just this big bump that comes up
initially now as it flattens out it will
kind of get kind of mushroom mushroomy
out at the edges so that there is a gap
between the bottom of that
and the and the ammonia cloud deck
and you can really in fact you could i
think you could actually see that it's
very high that pancake's very high up as
you saw in that last frame and if also
we noticed that the plume was somewhat
asymmetric and i think that's because
this is a directional
thing this this this thing the comet
pieces are not coming straight down onto
the atmosphere they're coming in at some
angle and
so in that sense it's a very different
kind of morphology different shape and
also in the little scenario i sketched
for you earlier um the plume doesn't
really necessarily rise straight up it
might come out that too blows outside it
blows out sideways
maybe
the second question is
when these three
fragments hit in the same location q r
and s does that increase the chances of
a cyclone effect
or an anticyclone that could be
permanent i'll tell you the answer to
that in about two or three days
after it happens
it does increase it or it has no effect
i really can't even speculate at this
point none of this stuff is something
that that we had expected to really see
so
um we're we're moving well into the
realm of speculation certainly it's
going to disturb the atmosphere a lot
more than a single impact on one site
would
i won't go much further than that though
okay we've got uh we've got time for one
more question before we go to the jet
propulsion laboratory
we'll take a question from right here
an automotive kyodo news service uh i
heard that japanese radio astronomers
reported that
they
had
seen
some something which indicates that
the fragment broke into two pieces uh
before impact and i'm wondering whether
the irregular shape
has something to do with that would you
comment on that
i saw a report on the internet about
some unusual radio signals and
all i can say to that is that the
signature of this impact the g
is very very similar to that scene for a
c and e the ones that we have good
images of so far does not appear to be
anything other than a solid single
main body or explosion or rubber rubble
pile it seems to be only one that i i
wanted to make sure to mention that
other site nearby to make sure that you
understood that that was an old impact
site that it was not related to g
so it doesn't look like a double one
from these images
okay we're going to go to the jet
propulsion laboratory now
jpl if you'd please state your name and
affiliation before asking your question
go
ahead you said you had some actual
numbers on the sizes of the spot and the
rings and the spot and the smudge
i wonder what those are can you can you
nod up and down if you can hear me
uh am i coming through now okay this is
robert lee host of the los angeles times
uh you mentioned a moment ago that you
had some actual numbers
on the uh estimated sizes of the spot
and the ring and the smudge
uh i wonder if we could hear those
numbers and then i have two quick
follow-ups
all right these are very very
preliminary preliminary we haven't had
much time to do detailed analysis
for our first cut analysis the diameter
of the black ring and if you show the
blow up version they'll have a better
idea of what i'm talking about
or the white ring if you have a methane
image available
the diameter of that sharp thin ring is
about 7 500 kilometers
and
the diameter of the
white
ring surrounding that the inside of the
black eye as it were that's about
15 thousand four hundred and fifty
kilometers
are there any other questions yes
just two quick uh follow-ups um
i wonder uh
and perhaps this is for gene shoemaker
if you could compare
uh in your mind the uh size and energy
of this
fragment to the object that is believed
to have caused the chixel upgrader
okay the minimum size of the chigzelub
crater and it's still a matter of
controversy the full crater i prefer the
to use the minimum value which is about
180 kilometers in diameter
so we're talking about something that's
uh three times smaller
and the energy
here then is 27 roughly about 27 times
less
so this is uh
this is a big event uh but it still
isn't the dinosaur killer
do we have any more questions from jpl
for us the level of uh internet email
traffic that you're seeing how crowded
is the electronic huddle
well
we have a a an email distribution
network set up for the professional
astronomy community and that is actually
working extraordinarily well people are
being very concise about reporting their
observations and therefore we are we
have in our parlance very high signal to
noise
a very good amount of information is
coming through
i when i saw there this morning that
that one of the um
images from the irtf showing the g
impact plume was posted on one of the
mosaic bulletin boards i tried to
connect and i could not get through and
they said that there was so much traffic
um on the networks trying to reach some
of these very popular sites that that uh
you know things are getting there
there's a big traffic jam on the
information super highway right now but
this is an extraordinary event i think
that's why normally we don't have that
kind of difficulty
are there any more questions from jpm
blackburn kcop tv in los angeles are you
getting any
readings yet to tell you the depth to
which these
impacts are going and or does it look
pretty much as though it's staying very
high in the atmosphere of jupiter
i don't think we have a good answer for
that question yet we're working on that
that kind of a question
you know we know something more about
the heights because we can see them
sticking away from jupiter it's awfully
hard to know about probing deep
one thing that will tell us for sure
is some spectroscopy that's being
planned by many telescopes around the
world including the irtf including the
kuiper airborne observatory and many
others looking for water the signature
of water if we see that
then we will know
how far
at least that particular
explosion went how far deep that
impacting body went because we
hypothesized the level at which the
water clouds reside we can't see it it's
below the visible cloud deck so that'll
be a clue as to the depth it could be
too that from these images we might be
able to pull out some of this
information that's going to take some
very clever thinking on our part and on
the part of the modelers to pull this
all together and and make a coherent
story i think we're still
far too premature to be able to answer
it with any certainty
walter richards of ktla los angeles i
have two questions would anything be
left of jupiter once this is all over
and uh what impact
would be what would the impact be on los
angeles if it were hit
i i think jupiter is going to hang in
there
it's pretty big planet and we're seeing
these these big splotches and black eyes
and bruises i feel sorry for jupiter
it's really getting pummeled but but i i
think it's going to hang in there and
the bruises will fade after some period
of time which which we don't know yet
i'll turn the los angeles question over
to gene that being my native hometown
well if this 60 kilometer crater is the
right estimate i think it's pretty good
and you put a bullseye over
city hall in los angeles that's going to
take out everything in the crater
it'll it'll take out all of la county
and in fact i just wouldn't want to be
in southern california period
okay if there are no more questions from
jpl we'll go to a marshall space flight
center uh once again please uh state
your name and affiliation before asking
your question
um oh this is masahiro takimura a
science writer for japanese newspaper
the yo miri shimbun i have questions
about the impact energy of fragments
as far as and i understand that
the
impact energy is proportional to the
cubit radius of
a fragment when the impact velocity is
the same is it all right
yes that's right the impact energy is
proportional the cube of the radius and
to the square of the velocity
do you have the estimated
figure of energy in terms of tnt
which is caused by the
impacts of all the
all the fragments of the
sl9
well you can start to add them up
we've seen perhaps the biggest
i'd multiply that by
a factor of uh maybe six to eight
might give us the total some somewhere
in that ballpark
so we're we're talking about something
of the order
of 40 million
megatons perhaps
of energy
very rough ballpark
give that a slosh of at least a factor
of 10 million megatons either way or
more because we you know we're just
going on what we've seen so far
okay we're going to leave marshall and
come back here to goddard to take any
more questions over here
um it's kind of an elementary school
question but
since
um jupiter is so much more massive than
earth
and gravity is pulling these guys in
therefore it's got a stronger stronger
gravity
wouldn't the comparable mass hit
jupiter with greater
velocity and therefore energy than than
it would earth
if i understand your question is if you
have the same mass
one's falling in jupiter and one's
falling on earth would you get would it
have more energy is that the question
we have more energy on jupiter because
jupiter has a larger mass and therefore
exactly
uh jupiter is accelerating these objects
as they come in
and in fact the the velocity with which
these fragments are hitting jupiter
essentially is the escape velocity from
jupiter's very and that's 60 kilometers
per second
whereas uh if you had an object that
just fell in at the escape velocity on
the earth that's only 11.2 kilometers
per second and the energy's going is the
square of the difference so it's it's a
factor of five and a half or something
like that square it so it's a factor of
difference of 30 in the energy that you
would get if so something just falls in
at the escape velocity
uh this is mark of houston chronicle i
think i appreciate how optimally the
planet was turned to get this picture
but i'm just curious
if this impact had had happened sooner
would it have been on the far side and
you would have missed it is there any
kind of a
a timing you can give us as to how how
lucky you were to capture this thing
well there the impacts are always
occurring on the far side timing is
irrelevant because they're coming in on
a line that always is the same
orientation relative for us and jupiter
so
it wouldn't matter if it came in earlier
late we would never be able to see it
in terms of the timing of the imaging
that we took
that for for our program was really
limited by the rotation of the hubble
the um the hubble space telescopes orbit
around the earth it orbits every 96
minutes and obviously we can only look
at it at jupiter when the space
telescope is on the side of the earth
that jupiter is visible you can't look
through the earth so
in some sense we have been extremely
lucky to have captured three of these
impact events in the middle of one of
the hubble's visibility windows
and it's almost by definition if if that
impact plume is visible
then one and a half hours later we'll be
able to take a picture of the site on
just on the disk of the planet because
that's how fast jupiter rotates
so
we were fortunate to have the hubble in
the right place at the right time to be
able to capture this one we couldn't
have done anything if the hubble had
been on the other side of the earth
i think part of the answer the question
heidi is that we already had very good
predictions
of the impact times they were they were
certainly good to within 15 minutes
and so that that was extraordinarily
important in the timing and the planning
for uh for these images that was a very
essential part
not really gene
because we we had to do the planning in
the sequences many weeks ago months ago
and the impact times were not well known
and the hubble's orbit was not
particularly well known either because
that has to be adjusted fairly
frequently and so at in some sense it
was potluck and and as as the predicts
were coming in and changing forward
backwards for they would be hopping in
and out of orbits and i'd be getting
very nervous and then i'd be very happy
and i'd be nervous again and and so i
ended up being very happy but but you
certainly were doing your initial
planning based based on that of course
from the chodest and yeoman's pre-that's
right but there were victims but it was
but there was a lot of luck that it came
out a lot of luck we've been very
fortunate
got a question in the middle right over
here tracy watson u.s news and world
report first of all um i'd heard that
looking at the plume may indicate
sometime what the composition of the
impactors was and will eventually tell
us whether it really was a comet or
whether it was an asteroid how long do
you think it'll take you to come out
with that kind of information
i'm not sure we'll get that information
from the plume itself although we'll
have to think about that for a while i
think it's more likely that kind of
information is going to come from
spectroscopy
of the impact sites the fresh impact
sites and that work will be done with a
variety of instruments hubble is one of
them in fact we had a very exciting
exercise this morning where we got that
first image that i showed you of the
impact site
on the limb and in real time we measured
exactly where the space tells telescope
was pointing
and then offset the telescope to be
pointing exactly at the impact site and
sent the instructions up to the
spacecraft normally we don't do that we
plan weeks and months in advance and
keith knoll is the principal
investigator of that experiment and at
some point in the near future i i hope
that he has some good results to
to share with you
other telescopes like the irtf and
nasa's kuiper airborne observatory will
be instrumental in doing the kind of
spectroscopy to probe the chemistry of
the atmosphere and of you know any
mushed up comet that happened to be
there
bill harwood cb cbs again
i think i know the answer but this this
is something that should be clearly
visible to amateurs is it not i mean
given its size or is the wavelength such
that it's not going to be visible like
which
well these black spots are starting to
get pretty darn big and
you know close to the size of the great
red spot
and i believe there have been some
reports from visual observers who are
starting to see them now remember
you have a very high resolution image in
front of you with the hubble space
telescope and with the ground-based
telescope much of this is smeared out
so it isn't anything like you're seeing
here through a ground-based telescope
but the short answer is that yes it
these are this is starting to get large
enough that that amateurs may be able to
spot these if they're very careful
observers and know what to look for and
that three three impact sequence
may stir up a real big portion of
atmosphere may get very dark it's also
possible that with time as the winds on
jupiter start to distribute this
material
it's possible that a slightly darker
band will will develop in this in this
latitudinal region
we say it's possible because as i
mentioned this material appears to be
very thinly deposited over that region
and so it's not clear if you start
spreading out that thin layer whether or
not there's enough there to make the
band dark we'll see that as it develops
over the next week or two
i think there's a good chance that that
amateurs with eight inch diameter
telescopes or bigger
in good sites where they have very good
seeing
will be able to see these i think and
already there are reports from from
quite reliable observers there's a
graphic we can show you that was shown
this morning which is the full disk of
jupiter and the three impact sites on
the bottom and i believe they have that
they can put on there it is you can see
the bands on jupiter this is roughly a
visual image this is a green wavelength
and that's more or less you know what
you would see with your eye and you can
see the bands and you can see the great
red spot and you can see the little dark
splotches following after the great red
spot
all right so if you can see the great
red spot moving it would start on on the
left of this image and move to the right
then look further south for that little
train of dark features and
you may see it
all right if there are no more questions
we'll wrap it up here we want to thank
everybody for their interest and we'll
see you
okay if any if people want to stay we're
going to roll some uh some visuals uh up
on the screen
good stuff that's good good good report
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you