I thought I’d talk about the sky now the advantage of talking about this guy is
advantage of talking about this guy is
advantage of talking about this guy is that almost everybody in this room has
that almost everybody in this room has
that almost everybody in this room has looked up and of course if you’re in the
looked up and of course if you’re in the
looked up and of course if you’re in the auditorium I don’t see this guy but if
auditorium I don’t see this guy but if
auditorium I don’t see this guy but if you’re outside you see this guy
you’re outside you see this guy
you’re outside you see this guy everybody has seen this guy the
everybody has seen this guy the
everybody has seen this guy the interesting thing is people see a lot of
interesting thing is people see a lot of
interesting thing is people see a lot of things but the sky is something that
things but the sky is something that
things but the sky is something that people think about as well I haven’t
people think about as well I haven’t
people think about as well I haven’t found anybody in my life
found anybody in my life
found anybody in my life who has not thought about the sky and of
who has not thought about the sky and of
who has not thought about the sky and of course you start thinking about the sky
course you start thinking about the sky
course you start thinking about the sky from a very early age like I for example
from a very early age like I for example
from a very early age like I for example very young looked up and I looked up at
very young looked up and I looked up at
very young looked up and I looked up at the sky and I thought what is what is it
the sky and I thought what is what is it
the sky and I thought what is what is it this we see the sky is it something is
this we see the sky is it something is
this we see the sky is it something is is it the firmament a bit of canvas a
is it the firmament a bit of canvas a
is it the firmament a bit of canvas a cloth hanging over you of course many
cloth hanging over you of course many
cloth hanging over you of course many cultures had stories about the sky the
cultures had stories about the sky the
cultures had stories about the sky the stars that you see in the sky maybe
stars that you see in the sky maybe
stars that you see in the sky maybe there’s some light behind this cloth
there’s some light behind this cloth
there’s some light behind this cloth this canvas that is above you and there
this canvas that is above you and there
this canvas that is above you and there are these holes in the canvas and light
are these holes in the canvas and light
are these holes in the canvas and light filters through this was the view of
filters through this was the view of
filters through this was the view of some of the ancients and then in many
some of the ancients and then in many
some of the ancients and then in many tribal localized people’s think about
tribal localized people’s think about
tribal localized people’s think about the sky as variants of of this kind of
the sky as variants of of this kind of
the sky as variants of of this kind of theory the sky of course to somebody on
theory the sky of course to somebody on
theory the sky of course to somebody on the earth as they look up they are
the earth as they look up they are
the earth as they look up they are looking into nothingness or is there
looking into nothingness or is there
looking into nothingness or is there something there if you of course are
something there if you of course are
something there if you of course are fortunate enough to have a very vivid
fortunate enough to have a very vivid
fortunate enough to have a very vivid imagination then you see the sky like
imagination then you see the sky like
imagination then you see the sky like this right and so here is of course we
this right and so here is of course we
this right and so here is of course we now know Bangkok of course probably had
now know Bangkok of course probably had
now know Bangkok of course probably had very blurry vision he had a condition
very blurry vision he had a condition
very blurry vision he had a condition where he could see some of this but this
where he could see some of this but this
where he could see some of this but this is also his imagination the sky
is also his imagination the sky
is also his imagination the sky a lot of variation of color and there
a lot of variation of color and there
a lot of variation of color and there are a lot of things happening in this
are a lot of things happening in this
are a lot of things happening in this guy right the sky has been very
guy right the sky has been very
guy right the sky has been very important in our lives all through
important in our lives all through
important in our lives all through history in very different ways for
history in very different ways for
history in very different ways for example if you grew up in Europe or in
example if you grew up in Europe or in
example if you grew up in Europe or in India you had your life being controlled
India you had your life being controlled
India you had your life being controlled by things in the sky this is called
by things in the sky this is called
by things in the sky this is called astrology of course and not everything
astrology of course and not everything
astrology of course and not everything in the sky of course but certain places
in the sky of course but certain places
in the sky of course but certain places in the sky which constituted certain
in the sky which constituted certain
in the sky which constituted certain constellations that have the stars that
constellations that have the stars that
constellations that have the stars that people thought control you then the
people thought control you then the
people thought control you then the changes in these constellations were
changes in these constellations were
changes in these constellations were very important because that told you
very important because that told you
very important because that told you whether something will change in your
whether something will change in your
whether something will change in your life similarly in the Chinese tradition
life similarly in the Chinese tradition
life similarly in the Chinese tradition the entire sky was important not just
the entire sky was important not just
the entire sky was important not just the constellations that form the 12
the constellations that form the 12
the constellations that form the 12 signs of the zodiac if the whole sky was
signs of the zodiac if the whole sky was
signs of the zodiac if the whole sky was important if this is why in the Chinese
important if this is why in the Chinese
important if this is why in the Chinese civilization
civilization
civilization the kings employed a very large number
the kings employed a very large number
the kings employed a very large number of people to look at the sky every day
of people to look at the sky every day
of people to look at the sky every day every hour every minute to document
every hour every minute to document
every hour every minute to document everything and this is why when as an
everything and this is why when as an
everything and this is why when as an astronomer I go back through records to
astronomer I go back through records to
astronomer I go back through records to find out what happened in the past in
find out what happened in the past in
find out what happened in the past in the sky in some part of the sky I go to
the sky in some part of the sky I go to
the sky in some part of the sky I go to Chinese records because they are very
Chinese records because they are very
Chinese records because they are very well documented because to them the
well documented because to them the
well documented because to them the entire sky was important right so the
entire sky was important right so the
entire sky was important right so the sky plays a very important role in our
sky plays a very important role in our
sky plays a very important role in our in our imagination and so of course you
in our imagination and so of course you
in our imagination and so of course you as you grow up then you start asking the
as you grow up then you start asking the
as you grow up then you start asking the real questions this guy that you see is
real questions this guy that you see is
real questions this guy that you see is there an end to the sky now this is a
there an end to the sky now this is a
there an end to the sky now this is a very famous woodcut it’s called the
very famous woodcut it’s called the
very famous woodcut it’s called the Flammarion a woodcut that comes from a
Flammarion a woodcut that comes from a
Flammarion a woodcut that comes from a book from the 19th century but actually
book from the 19th century but actually
book from the 19th century but actually it refers to a legend from early on
it refers to a legend from early on
it refers to a legend from early on about this traveler who had traveled to
about this traveler who had traveled to
about this traveler who had traveled to the end of the world and as you can see
the end of the world and as you can see
the end of the world and as you can see look
look
look has looked through the sky beyond what
has looked through the sky beyond what
has looked through the sky beyond what is there as you know in the Greek
is there as you know in the Greek
is there as you know in the Greek tradition when where the earth is at the
tradition when where the earth is at the
tradition when where the earth is at the center of the system and the planets
center of the system and the planets
center of the system and the planets move on crystal spheres around the earth
move on crystal spheres around the earth
move on crystal spheres around the earth the last sphere is a sphere that makes
the last sphere is a sphere that makes
the last sphere is a sphere that makes the universe move the entire world move
the universe move the entire world move
the universe move the entire world move and this movement is caused by some
and this movement is caused by some
and this movement is caused by some system outside right and and that same
system outside right and and that same
system outside right and and that same system could be angels that tunnel
system could be angels that tunnel
system could be angels that tunnel system could be a very elaborate system
system could be a very elaborate system
system could be a very elaborate system of divine gears or engineering apparatus
of divine gears or engineering apparatus
of divine gears or engineering apparatus people had wild imagination about what
people had wild imagination about what
people had wild imagination about what makes the world move and maybe people
makes the world move and maybe people
makes the world move and maybe people thought that this outermost fear is the
thought that this outermost fear is the
thought that this outermost fear is the sky right and so here you are here is
sky right and so here you are here is
sky right and so here you are here is somebody looking out and discovering the
somebody looking out and discovering the
somebody looking out and discovering the gears that move the world and you can
gears that move the world and you can
gears that move the world and you can see that the stars in this in this idea
see that the stars in this in this idea
see that the stars in this in this idea of course this is a 19th century vodka
of course this is a 19th century vodka
of course this is a 19th century vodka but of course this depict a pre
but of course this depict a pre
but of course this depict a pre Copernican idea that the stars are all
Copernican idea that the stars are all
Copernican idea that the stars are all at the same distance as the planets and
at the same distance as the planets and
at the same distance as the planets and they all surround the earth and we are
they all surround the earth and we are
they all surround the earth and we are looking beyond now to us now to us who
looking beyond now to us now to us who
looking beyond now to us now to us who have telescopes who can look very far
have telescopes who can look very far
have telescopes who can look very far away and telescopes all kinds as we
away and telescopes all kinds as we
away and telescopes all kinds as we start discovering about the universe
start discovering about the universe
start discovering about the universe what do we find out about the sky so
what do we find out about the sky so
what do we find out about the sky so here is a picture of the night sky now
here is a picture of the night sky now
here is a picture of the night sky now what do you see here it’s a very very
what do you see here it’s a very very
what do you see here it’s a very very interesting picture to me it’s one of
interesting picture to me it’s one of
interesting picture to me it’s one of the best pictures ever taken in
the best pictures ever taken in
the best pictures ever taken in astronomy and this depicts this is
astronomy and this depicts this is
astronomy and this depicts this is business from 1979 taken by a very
business from 1979 taken by a very
business from 1979 taken by a very famous man called David Malin who’s was
famous man called David Malin who’s was
famous man called David Malin who’s was a pioneers of this subject called Astro
a pioneers of this subject called Astro
a pioneers of this subject called Astro photography and what it does is this is
photography and what it does is this is
photography and what it does is this is a a very long exposure in fact of the
a a very long exposure in fact of the
a a very long exposure in fact of the whole of the of the sky from a camera
whole of the of the sky from a camera
whole of the of the sky from a camera that was left open the entire night
that was left open the entire night
that was left open the entire night right and you can see why because
right and you can see why because
right and you can see why because you see is in each case each trail that
you see is in each case each trail that
you see is in each case each trail that you see is a part of a circle and that
you see is a part of a circle and that
you see is a part of a circle and that part of a circle tells you that that is
part of a circle tells you that that is
part of a circle tells you that that is actually a star that has moved all
actually a star that has moved all
actually a star that has moved all through the time in which the camera was
through the time in which the camera was
through the time in which the camera was kept open right and of course the earth
kept open right and of course the earth
kept open right and of course the earth moves ie and the sky moves with respect
moves ie and the sky moves with respect
moves ie and the sky moves with respect to us so each star moves with the earth
to us so each star moves with the earth
to us so each star moves with the earth so you can see that each star has moved
so you can see that each star has moved
so you can see that each star has moved exactly the the amount of time that the
exactly the the amount of time that the
exactly the the amount of time that the camera has been open and the place that
camera has been open and the place that
camera has been open and the place that has not moved is the pole star of course
has not moved is the pole star of course
has not moved is the pole star of course is the pole around which the entire sky
is the pole around which the entire sky
is the pole around which the entire sky moves you can also see that each of
moves you can also see that each of
moves you can also see that each of these trails since they depict a star
these trails since they depict a star
these trails since they depict a star tell you that stars have different
tell you that stars have different
tell you that stars have different colors there are some red stars there
colors there are some red stars there
colors there are some red stars there are some blue stars there are some
are some blue stars there are some
are some blue stars there are some yellow stars but each one of them has
yellow stars but each one of them has
yellow stars but each one of them has moved exactly the same amount because
moved exactly the same amount because
moved exactly the same amount because and and of course in here you can see
and and of course in here you can see
and and of course in here you can see during the time which is roughly about
during the time which is roughly about
during the time which is roughly about 10 hours or so this is from Australia
10 hours or so this is from Australia
10 hours or so this is from Australia this is at angle Australian telescope so
this is at angle Australian telescope so
this is at angle Australian telescope so actually at the pole there where you are
actually at the pole there where you are
actually at the pole there where you are seeing the center of those circles there
seeing the center of those circles there
seeing the center of those circles there is no pole star there is no southern
is no pole star there is no southern
is no pole star there is no southern pole star of course and everything moves
pole star of course and everything moves
pole star of course and everything moves around a point in the sky where which is
around a point in the sky where which is
around a point in the sky where which is the same direction as the Earth’s
the same direction as the Earth’s
the same direction as the Earth’s rotational axis this is in Australia and
rotational axis this is in Australia and
rotational axis this is in Australia and you can see that during this time when
you can see that during this time when
you can see that during this time when the camera has been opened a car has
the camera has been opened a car has
the camera has been opened a car has come and gone too and come out and there
come and gone too and come out and there
come and gone too and come out and there is somebody who’s on the or near the top
is somebody who’s on the or near the top
is somebody who’s on the or near the top of the telescope who has come out and
of the telescope who has come out and
of the telescope who has come out and smoked a cigarette and gone in and
smoked a cigarette and gone in and
smoked a cigarette and gone in and that’s all recorded very dutifully in in
that’s all recorded very dutifully in in
that’s all recorded very dutifully in in this long exposure why am i showing you
this long exposure why am i showing you
this long exposure why am i showing you this
this
this because this tells you that something
because this tells you that something
because this tells you that something that your eye cannot see because one of
that your eye cannot see because one of
that your eye cannot see because one of the limitations of our eye is that we
the limitations of our eye is that we
the limitations of our eye is that we cannot see anything for more than a
cannot see anything for more than a
cannot see anything for more than a tenth of a second because our brain
tenth of a second because our brain
tenth of a second because our brain eliminates any picture that comes in to
eliminates any picture that comes in to
eliminates any picture that comes in to our eye after a tenth of a second and
our eye after a tenth of a second and
our eye after a tenth of a second and goes on
goes on
goes on to the next picture it’s gone you cannot
to the next picture it’s gone you cannot
to the next picture it’s gone you cannot keep it any longer whereas if you have a
keep it any longer whereas if you have a
keep it any longer whereas if you have a detector what you can do is then you can
detector what you can do is then you can
detector what you can do is then you can change the duration of it and collect
change the duration of it and collect
change the duration of it and collect the light and keep it there right so you
the light and keep it there right so you
the light and keep it there right so you will never be able to in fact if you do
will never be able to in fact if you do
will never be able to in fact if you do wonder if you look at the sky and see
wonder if you look at the sky and see
wonder if you look at the sky and see this picture something’s wrong with you
this picture something’s wrong with you
this picture something’s wrong with you right so you cannot of course your your
right so you cannot of course your your
right so you cannot of course your your vision can’t persist for eight or ten
vision can’t persist for eight or ten
vision can’t persist for eight or ten hours but what you see here is that for
hours but what you see here is that for
hours but what you see here is that for the ten hours that has gone into this
the ten hours that has gone into this
the ten hours that has gone into this picture not only do you see the stars
picture not only do you see the stars
picture not only do you see the stars they seem to fill the sky and that’s
they seem to fill the sky and that’s
they seem to fill the sky and that’s because each each star has gone around
because each each star has gone around
because each each star has gone around almost a half circle and more and any
almost a half circle and more and any
almost a half circle and more and any direction you look there are these star
direction you look there are these star
direction you look there are these star trails right and these are only the
trails right and these are only the
trails right and these are only the brightest stars there are many more
brightest stars there are many more
brightest stars there are many more stars that are faint to them that but
stars that are faint to them that but
stars that are faint to them that but together they give the sky your color
together they give the sky your color
together they give the sky your color right now I can ask you the same
right now I can ask you the same
right now I can ask you the same question this is taken at night this is
question this is taken at night this is
question this is taken at night this is the whole night what happens if you do
the whole night what happens if you do
the whole night what happens if you do the same thing during the day what
the same thing during the day what
the same thing during the day what happens if you keep your camera open in
happens if you keep your camera open in
happens if you keep your camera open in the day and look at the sky this is what
the day and look at the sky this is what
the day and look at the sky this is what happens so this is a daytime photograph
happens so this is a daytime photograph
happens so this is a daytime photograph and the exposure is a little over an
and the exposure is a little over an
and the exposure is a little over an hour so it’s one and a half hours and
hour so it’s one and a half hours and
hour so it’s one and a half hours and you can see that you can see the stars
you can see that you can see the stars
you can see that you can see the stars same thing right the stars are there if
same thing right the stars are there if
same thing right the stars are there if you if you can get a deep image of the
you if you can get a deep image of the
you if you can get a deep image of the sky then the stars are there the stars
sky then the stars are there the stars
sky then the stars are there the stars are but where is where are the stars all
are but where is where are the stars all
are but where is where are the stars all the stars in front of the sky like in
the stars in front of the sky like in
the stars in front of the sky like in the woodcut all are the stars beyond the
the woodcut all are the stars beyond the
the woodcut all are the stars beyond the sky as in the case of you know the other
sky as in the case of you know the other
sky as in the case of you know the other legends we talked about is there a sky
legends we talked about is there a sky
legends we talked about is there a sky at all the interesting thing is we see
at all the interesting thing is we see
at all the interesting thing is we see the sky but the sky isn’t if it is an
the sky but the sky isn’t if it is an
the sky but the sky isn’t if it is an ephemeral thing isn’t it the sky is just
ephemeral thing isn’t it the sky is just
ephemeral thing isn’t it the sky is just the air the sky is just the atmosphere
the air the sky is just the atmosphere
the air the sky is just the atmosphere and the sky is full of the sun’s light
and the sky is full of the sun’s light
and the sky is full of the sun’s light that goes all around us because it
that goes all around us because it
that goes all around us because it scattered by the air molecules in the
scattered by the air molecules in the
scattered by the air molecules in the atmosphere and if the atmosphere weren’t
atmosphere and if the atmosphere weren’t
atmosphere and if the atmosphere weren’t there then you would not see the sky
there then you would not see the sky
there then you would not see the sky this notion of the sky is now emerging
this notion of the sky is now emerging
this notion of the sky is now emerging as the sky is nothing there but this is
as the sky is nothing there but this is
as the sky is nothing there but this is just just a light filling up that
just just a light filling up that
just just a light filling up that Monsieur so the question is what happens
Monsieur so the question is what happens
Monsieur so the question is what happens when you go outside the atmosphere the
when you go outside the atmosphere the
when you go outside the atmosphere the first astronaut I ever met was almost 25
first astronaut I ever met was almost 25
first astronaut I ever met was almost 25 years ago a man called Jeffrey Hoffman
years ago a man called Jeffrey Hoffman
years ago a man called Jeffrey Hoffman who when I was at Harvard he came back
who when I was at Harvard he came back
who when I was at Harvard he came back to his alma mater he was somebody who
to his alma mater he was somebody who
to his alma mater he was somebody who was captain of the space shuttle and
was captain of the space shuttle and
was captain of the space shuttle and also he’d gone up about five times when
also he’d gone up about five times when
also he’d gone up about five times when I met him it was just after his fourth
I met him it was just after his fourth
I met him it was just after his fourth trip he was the captain of the space
trip he was the captain of the space
trip he was the captain of the space shuttle mission that went to repair the
shuttle mission that went to repair the
shuttle mission that went to repair the Hubble Space Telescope the first time
Hubble Space Telescope the first time
Hubble Space Telescope the first time this was 9 December 93 and it come to
this was 9 December 93 and it come to
this was 9 December 93 and it come to visit us in December in January 94 to
visit us in December in January 94 to
visit us in December in January 94 to give a talk about his trip to the Hubble
give a talk about his trip to the Hubble
give a talk about his trip to the Hubble Space Telescope and one of the first
Space Telescope and one of the first
Space Telescope and one of the first questions I asked him when I got a
questions I asked him when I got a
questions I asked him when I got a chance to talk to him was what was the
chance to talk to him was what was the
chance to talk to him was what was the most unexpected thing about going out in
most unexpected thing about going out in
most unexpected thing about going out in space it is always wanted I always
space it is always wanted I always
space it is always wanted I always wanted to know I knew that I would never
wanted to know I knew that I would never
wanted to know I knew that I would never probably become an astronaut but I
probably become an astronaut but I
probably become an astronaut but I wanted to know what is the biggest
wanted to know what is the biggest
wanted to know what is the biggest surprise and he said the biggest
surprise and he said the biggest
surprise and he said the biggest surprise was he thought about it a
surprise was he thought about it a
surprise was he thought about it a little and is interesting he said a
little and is interesting he said a
little and is interesting he said a biggest surprise was to see the Sun
biggest surprise was to see the Sun
biggest surprise was to see the Sun against the black sky what is the sky
against the black sky what is the sky
against the black sky what is the sky then the sky is the emptiness it’s black
then the sky is the emptiness it’s black
then the sky is the emptiness it’s black he is outside the atmosphere there the
he is outside the atmosphere there the
he is outside the atmosphere there the Sun is just a disk it’s light doesn’t
Sun is just a disk it’s light doesn’t
Sun is just a disk it’s light doesn’t fill everything because there’s no end
fill everything because there’s no end
fill everything because there’s no end think about it it is just a black canvas
think about it it is just a black canvas
think about it it is just a black canvas and just a yellow disk on it and he said
and just a yellow disk on it and he said
and just a yellow disk on it and he said it was very uncanny he got very
it was very uncanny he got very
it was very uncanny he got very disoriented he wasn’t he didn’t think
disoriented he wasn’t he didn’t think
disoriented he wasn’t he didn’t think that the Sun would be up in the sky and
that the Sun would be up in the sky and
that the Sun would be up in the sky and there would be no sky so here’s an
there would be no sky so here’s an
there would be no sky so here’s an astronaut going up there and he’s
astronaut going up there and he’s
astronaut going up there and he’s unnerved because there is no sky what
unnerved because there is no sky what
unnerved because there is no sky what happens if you go outside the atmosphere
happens if you go outside the atmosphere
happens if you go outside the atmosphere do you see no light at all
do you see no light at all
do you see no light at all actually you do so here’s a picture
actually you do so here’s a picture
actually you do so here’s a picture which you will see if you send a
which you will see if you send a
which you will see if you send a satellite outside the atmosphere you can
satellite outside the atmosphere you can
satellite outside the atmosphere you can see actually this is not taken from
see actually this is not taken from
see actually this is not taken from outside they preserve it you’ll see it
outside they preserve it you’ll see it
outside they preserve it you’ll see it everything will be dark but right in the
everything will be dark but right in the
everything will be dark but right in the middle you can see there’s an
middle you can see there’s an
middle you can see there’s an illumination there it’s called the
illumination there it’s called the
illumination there it’s called the zodiacal light so if you think that you
zodiacal light so if you think that you
zodiacal light so if you think that you send a satellite up on the outside
send a satellite up on the outside
send a satellite up on the outside atmosphere and you don’t see a sky at
atmosphere and you don’t see a sky at
atmosphere and you don’t see a sky at all that is not true because in the
all that is not true because in the
all that is not true because in the plane of the solar system comets come
plane of the solar system comets come
plane of the solar system comets come and go and as comets come and go they
and go and as comets come and go they
and go and as comets come and go they melt and they leave dust everywhere and
melt and they leave dust everywhere and
melt and they leave dust everywhere and the Comets come and go in a plane called
the Comets come and go in a plane called
the Comets come and go in a plane called ecliptic it’s in the same plane as all
ecliptic it’s in the same plane as all
ecliptic it’s in the same plane as all the planets and the earth that go around
the planets and the earth that go around
the planets and the earth that go around the Sun so there’s only one plane as you
the Sun so there’s only one plane as you
the Sun so there’s only one plane as you can see there’s a plane there and in
can see there’s a plane there and in
can see there’s a plane there and in that plane there’s a lot of dust and the
that plane there’s a lot of dust and the
that plane there’s a lot of dust and the sun’s light is scattered all over just
sun’s light is scattered all over just
sun’s light is scattered all over just like the Sun lies it scattered in the
like the Sun lies it scattered in the
like the Sun lies it scattered in the air molecules in our atmosphere it is
air molecules in our atmosphere it is
air molecules in our atmosphere it is scattered all over the solar system so
scattered all over the solar system so
scattered all over the solar system so you can’t escape from it from that light
you can’t escape from it from that light
you can’t escape from it from that light but it’s now not filling everything but
but it’s now not filling everything but
but it’s now not filling everything but it’s in a flat plane and it’s all over
it’s in a flat plane and it’s all over
it’s in a flat plane and it’s all over in the solar system you have to go all
in the solar system you have to go all
in the solar system you have to go all the way up to Neptune and Pluto to
the way up to Neptune and Pluto to
the way up to Neptune and Pluto to escape from it so if you’re going out in
escape from it so if you’re going out in
escape from it so if you’re going out in the solar system you’re not escaping
the solar system you’re not escaping
the solar system you’re not escaping from it there’s still light but then the
from it there’s still light but then the
from it there’s still light but then the sky is a flat plane it is not everywhere
sky is a flat plane it is not everywhere
sky is a flat plane it is not everywhere if sky means to you the light that fills
if sky means to you the light that fills
if sky means to you the light that fills you know your surroundings what happens
you know your surroundings what happens
you know your surroundings what happens after that
after that
after that so can you escape from it so here’s a
so can you escape from it so here’s a
so can you escape from it so here’s a very interesting plot that shows you how
very interesting plot that shows you how
very interesting plot that shows you how to observe what’s in the sky now as an
to observe what’s in the sky now as an
to observe what’s in the sky now as an astronomer I would like to study the
astronomer I would like to study the
astronomer I would like to study the universe not just by the light that is
universe not just by the light that is
universe not just by the light that is emitted from it but from the various
emitted from it but from the various
emitted from it but from the various other kinds of radiation that come from
other kinds of radiation that come from
other kinds of radiation that come from it of course as all of you know
it of course as all of you know
it of course as all of you know electromagnetic radiation is of one kind
electromagnetic radiation is of one kind
electromagnetic radiation is of one kind and depending upon what its wavelength
and depending upon what its wavelength
and depending upon what its wavelength or frequency or energy is
or frequency or energy is
or frequency or energy is we call them radio waves and gamma rays
we call them radio waves and gamma rays
we call them radio waves and gamma rays and x-rays and infrared or light or
and x-rays and infrared or light or
and x-rays and infrared or light or ultraviolet etc radio waves are the
ultraviolet etc radio waves are the
ultraviolet etc radio waves are the lowest energy the highest energy or
lowest energy the highest energy or
lowest energy the highest energy or x-rays and gamma-rays
x-rays and gamma-rays
x-rays and gamma-rays now the interesting thing is you can see
now the interesting thing is you can see
now the interesting thing is you can see this plot tells you that the atmosphere
this plot tells you that the atmosphere
this plot tells you that the atmosphere doesn’t let in most of these rays okay
doesn’t let in most of these rays okay
doesn’t let in most of these rays okay it’s only one small part of the
it’s only one small part of the
it’s only one small part of the electromagnetic spectrum that is in and
electromagnetic spectrum that is in and
electromagnetic spectrum that is in and around what we call light that comes in
around what we call light that comes in
around what we call light that comes in through and that’s right in the middle
through and that’s right in the middle
through and that’s right in the middle it’s called the optical window in this
it’s called the optical window in this
it’s called the optical window in this plot it comes in right in the middle and
plot it comes in right in the middle and
plot it comes in right in the middle and other than that the atmosphere is opaque
other than that the atmosphere is opaque
other than that the atmosphere is opaque all the way through from x-rays to
all the way through from x-rays to
all the way through from x-rays to ultraviolet that’s good for us because
ultraviolet that’s good for us because
ultraviolet that’s good for us because these things are stopped at ozone layer
these things are stopped at ozone layer
these things are stopped at ozone layer otherwise we would have skin cancer
otherwise we would have skin cancer
otherwise we would have skin cancer everywhere if you have x-rays and gamma
everywhere if you have x-rays and gamma
everywhere if you have x-rays and gamma rays raining of your on you all the time
rays raining of your on you all the time
rays raining of your on you all the time and then you can also see that since
and then you can also see that since
and then you can also see that since there is carbon dioxide and water in
there is carbon dioxide and water in
there is carbon dioxide and water in particular in that mosque fear no
particular in that mosque fear no
particular in that mosque fear no infrared comes in through and most much
infrared comes in through and most much
infrared comes in through and most much of the radio waves come in and then you
of the radio waves come in and then you
of the radio waves come in and then you have nothing else right now think about
have nothing else right now think about
have nothing else right now think about this there are so many kinds of
this there are so many kinds of
this there are so many kinds of radiation so many kinds of light only a
radiation so many kinds of light only a
radiation so many kinds of light only a little bit that describes the optical
little bit that describes the optical
little bit that describes the optical window is open for light to come through
window is open for light to come through
window is open for light to come through how come our eyes can see only that
how come our eyes can see only that
how come our eyes can see only that optical light if our eyes were sensitive
optical light if our eyes were sensitive
optical light if our eyes were sensitive to radio emission we would not see the
to radio emission we would not see the
to radio emission we would not see the stars we would not see the sky our sky
stars we would not see the sky our sky
stars we would not see the sky our sky would be dark our sky has stars in it
would be dark our sky has stars in it
would be dark our sky has stars in it because our eyes are sensitive to a
because our eyes are sensitive to a
because our eyes are sensitive to a range of radiation that has wavelength
range of radiation that has wavelength
range of radiation that has wavelength between 300 nanometers and 800
between 300 nanometers and 800
between 300 nanometers and 800 nanometers that’s it whereas the
nanometers that’s it whereas the
nanometers that’s it whereas the radiation can have wavelength from you
radiation can have wavelength from you
radiation can have wavelength from you know whatever the entire range so that
know whatever the entire range so that
know whatever the entire range so that is a very interesting thing if you think
is a very interesting thing if you think
is a very interesting thing if you think of there are Apple snakes that can only
of there are Apple snakes that can only
of there are Apple snakes that can only see in the infrared there are no
see in the infrared there are no
see in the infrared there are no rattlesnake astronomers because they
rattlesnake astronomers because they
rattlesnake astronomers because they don’t see any stars
don’t see any stars
don’t see any stars their sky is completely dark question is
their sky is completely dark question is
their sky is completely dark question is it’s a philosophical question if you
it’s a philosophical question if you
it’s a philosophical question if you didn’t see the Stars if truly our eyes
didn’t see the Stars if truly our eyes
didn’t see the Stars if truly our eyes were x-ray eyes would we know that there
were x-ray eyes would we know that there
were x-ray eyes would we know that there is a universe out there so now I would
is a universe out there so now I would
is a universe out there so now I would like to study the universe in the entire
like to study the universe in the entire
like to study the universe in the entire electromagnetic spectrum because
electromagnetic spectrum because
electromagnetic spectrum because different parts of this spectrum gives
different parts of this spectrum gives
different parts of this spectrum gives the information different kinds of
the information different kinds of
the information different kinds of information to us about the stars and
information to us about the stars and
information to us about the stars and the galaxies and the planets so if I
the galaxies and the planets so if I
the galaxies and the planets so if I want to find out what is a million
want to find out what is a million
want to find out what is a million degrees hot in the universe I am NOT
degrees hot in the universe I am NOT
degrees hot in the universe I am NOT able to see it from the earth and to do
able to see it from the earth and to do
able to see it from the earth and to do that I have to go to space so I have to
that I have to go to space so I have to
that I have to go to space so I have to go to space and I have to go very far
go to space and I have to go very far
go to space and I have to go very far away so that I get rid of the atmosphere
away so that I get rid of the atmosphere
away so that I get rid of the atmosphere but am i safe can I still see through
but am i safe can I still see through
but am i safe can I still see through the sky what happens here is no as usual
the sky what happens here is no as usual
the sky what happens here is no as usual this is not working
this is not working
this is not working yeah so here what happens is that if you
yeah so here what happens is that if you
yeah so here what happens is that if you look at the middle I don’t know whether
look at the middle I don’t know whether
look at the middle I don’t know whether this is a right in the middle is the
this is a right in the middle is the
this is a right in the middle is the earth the tiny earth and all around it
earth the tiny earth and all around it
earth the tiny earth and all around it it is surrounded by a very strong field
it is surrounded by a very strong field
it is surrounded by a very strong field of charged particles that are attracted
of charged particles that are attracted
of charged particles that are attracted to the magnetic field of the earth and
to the magnetic field of the earth and
to the magnetic field of the earth and that all comes from the Sun the Sun is
that all comes from the Sun the Sun is
that all comes from the Sun the Sun is radiating a lot of charged particles
radiating a lot of charged particles
radiating a lot of charged particles they come and the earth is sitting in
they come and the earth is sitting in
they come and the earth is sitting in this big soup and this soup goes out all
this big soup and this soup goes out all
this big soup and this soup goes out all the way to about 30,000 kilometers and
the way to about 30,000 kilometers and
the way to about 30,000 kilometers and the earth is sitting in this soup now it
the earth is sitting in this soup now it
the earth is sitting in this soup now it doesn’t make a difference to me because
doesn’t make a difference to me because
doesn’t make a difference to me because all this these charged particles
all this these charged particles
all this these charged particles actually are radiating a lot of very
actually are radiating a lot of very
actually are radiating a lot of very high-energy photons x-rays gamma rays
high-energy photons x-rays gamma rays
high-energy photons x-rays gamma rays sometimes they come very close to the
sometimes they come very close to the
sometimes they come very close to the earth and create the aurora borealis as
earth and create the aurora borealis as
earth and create the aurora borealis as you know at the poles if I send out a
you know at the poles if I send out a
you know at the poles if I send out a x-ray satellite to observe x-rays from a
x-ray satellite to observe x-rays from a
x-ray satellite to observe x-rays from a star or a galaxy they have to go all the
star or a galaxy they have to go all the
star or a galaxy they have to go all the way out of these than Allen belts
way out of these than Allen belts
way out of these than Allen belts because otherwise they would only see
because otherwise they would only see
because otherwise they would only see these charged particles that are around
these charged particles that are around
these charged particles that are around the earth their sky their x-ray sky are
the earth their sky their x-ray sky are
the earth their sky their x-ray sky are these particles so you can see it’s the
these particles so you can see it’s the
these particles so you can see it’s the sky definition
sky definition
sky definition sky changes according to what we are
sky changes according to what we are
sky changes according to what we are trying to observe so this is what
trying to observe so this is what
trying to observe so this is what happens for for a telescope so this is a
happens for for a telescope so this is a
happens for for a telescope so this is a telescope that I was involved in
telescope that I was involved in
telescope that I was involved in building comment up in 1999
building comment up in 1999
building comment up in 1999 it’s a NASA project named after Chandra
it’s a NASA project named after Chandra
it’s a NASA project named after Chandra Shekar switch called Chandra and when we
Shekar switch called Chandra and when we
Shekar switch called Chandra and when we realized that this was the first
realized that this was the first
realized that this was the first telescope which had exquisite imaging
telescope which had exquisite imaging
telescope which had exquisite imaging quality imaging as good as the Hubble
quality imaging as good as the Hubble
quality imaging as good as the Hubble Space Telescope but in the x-rays the
Space Telescope but in the x-rays the
Space Telescope but in the x-rays the first time it had mirrors that were
first time it had mirrors that were
first time it had mirrors that were capable of doing this we realized that
capable of doing this we realized that
capable of doing this we realized that if we had to build this telescope and
if we had to build this telescope and
if we had to build this telescope and have it observe not the sky that is near
have it observe not the sky that is near
have it observe not the sky that is near the earth but actually things that are
the earth but actually things that are
the earth but actually things that are out there we will have to choose an
out there we will have to choose an
out there we will have to choose an orbit that goes way out beyond the Van
orbit that goes way out beyond the Van
orbit that goes way out beyond the Van Andel belt so that’s why you can see for
Andel belt so that’s why you can see for
Andel belt so that’s why you can see for the first time we have an orbit that is
the first time we have an orbit that is
the first time we have an orbit that is silly you know the Hubble Space
silly you know the Hubble Space
silly you know the Hubble Space Telescope goes around the earth every 90
Telescope goes around the earth every 90
Telescope goes around the earth every 90 minutes it is a few hundred kilometers
minutes it is a few hundred kilometers
minutes it is a few hundred kilometers above the earth where as the thing goes
above the earth where as the thing goes
above the earth where as the thing goes out to 26,000 kilometers that’s the
out to 26,000 kilometers that’s the
out to 26,000 kilometers that’s the nearest distance and 122 thousand
nearest distance and 122 thousand
nearest distance and 122 thousand kilometers away because it has to go
kilometers away because it has to go
kilometers away because it has to go very far away from this local x-ray sky
very far away from this local x-ray sky
very far away from this local x-ray sky it has to go out of our sky and when it
it has to go out of our sky and when it
it has to go out of our sky and when it comes as close as 60,000 kilometers to
comes as close as 60,000 kilometers to
comes as close as 60,000 kilometers to the earth we shut it down because then
the earth we shut it down because then
the earth we shut it down because then only does it observes the charged
only does it observes the charged
only does it observes the charged particles in the Van Allen belts it
particles in the Van Allen belts it
particles in the Van Allen belts it observes this guy right
observes this guy right
observes this guy right so it takes 64 hours for it to go but
so it takes 64 hours for it to go but
so it takes 64 hours for it to go but come and go and come back but we can
come and go and come back but we can
come and go and come back but we can observe with it for only about 30 hours
observe with it for only about 30 hours
observe with it for only about 30 hours or so every time because it has to be
or so every time because it has to be
or so every time because it has to be shot the entire time in fact it is if
shot the entire time in fact it is if
shot the entire time in fact it is if it’s open the charged particles will
it’s open the charged particles will
it’s open the charged particles will destroy its detectors here’s a picture
destroy its detectors here’s a picture
destroy its detectors here’s a picture of a galaxy called Centaurus a and the
of a galaxy called Centaurus a and the
of a galaxy called Centaurus a and the picture that you see here is a picture
picture that you see here is a picture
picture that you see here is a picture taken in conventional light the kind of
taken in conventional light the kind of
taken in conventional light the kind of light that our eyes would see taking
light that our eyes would see taking
light that our eyes would see taking with an earthbound telescope through
with an earthbound telescope through
with an earthbound telescope through our optical sky and what you see here is
our optical sky and what you see here is
our optical sky and what you see here is a galaxy it’s actually a collision of
a galaxy it’s actually a collision of
a galaxy it’s actually a collision of two galaxies you see a dust Lane but a
two galaxies you see a dust Lane but a
two galaxies you see a dust Lane but a nice round galaxy and everything you see
nice round galaxy and everything you see
nice round galaxy and everything you see in here is a few thousand degrees hot
in here is a few thousand degrees hot
in here is a few thousand degrees hot about two to ten thousand degrees out we
about two to ten thousand degrees out we
about two to ten thousand degrees out we know that because that’s the kind of
know that because that’s the kind of
know that because that’s the kind of things that produce the radiation that
things that produce the radiation that
things that produce the radiation that our eyes can see but when we send out a
our eyes can see but when we send out a
our eyes can see but when we send out a telescope like chandra up in I won’t say
telescope like chandra up in I won’t say
telescope like chandra up in I won’t say the sky in space and make it go beyond
the sky in space and make it go beyond
the sky in space and make it go beyond what I call the x-ray sky remember that
what I call the x-ray sky remember that
what I call the x-ray sky remember that I call this talk why we have to go to
I call this talk why we have to go to
I call this talk why we have to go to space to see the sky when we have to go
space to see the sky when we have to go
space to see the sky when we have to go to space to go beyond the sky that the
to space to go beyond the sky that the
to space to go beyond the sky that the x-ray telescopes experience then you see
x-ray telescopes experience then you see
x-ray telescopes experience then you see something like this and that’s the x-ray
something like this and that’s the x-ray
something like this and that’s the x-ray picture of the same galaxies and
picture of the same galaxies and
picture of the same galaxies and everything you see in here is more than
everything you see in here is more than
everything you see in here is more than ten million degrees hot each individual
ten million degrees hot each individual
ten million degrees hot each individual point you see is a black hole which is
point you see is a black hole which is
point you see is a black hole which is orbiting another star the big jet that
orbiting another star the big jet that
orbiting another star the big jet that you see is gas that is ten million
you see is gas that is ten million
you see is gas that is ten million degrees hotter or more that is being
degrees hotter or more that is being
degrees hotter or more that is being ejected by the central black hole in the
ejected by the central black hole in the
ejected by the central black hole in the galaxies and all that is completely
galaxies and all that is completely
galaxies and all that is completely invisible to our eyes so I hope that now
invisible to our eyes so I hope that now
invisible to our eyes so I hope that now you realized that the word sky is very
you realized that the word sky is very
you realized that the word sky is very very relative and the sky that your
very relative and the sky that your
very relative and the sky that your thought is going to fall on your heads
thought is going to fall on your heads
thought is going to fall on your heads is actually really ephemeral and the sky
is actually really ephemeral and the sky
is actually really ephemeral and the sky means very different depending on what
means very different depending on what
means very different depending on what you’re observing thank you
you’re observing thank you
you’re observing thank you [Applause]
”
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