Full transcript
0:00another thing that's worth noting is
0:02that the resolution we have on earth is
0:05actually limited for a while there they
0:09were building better and better
0:10telescopes and they started noticing
0:12that wait we weren't getting as clear an
0:15image as we expected as Theory predicted
0:18we weren't seeing this high-end
0:20resolution as we would hope we couldn't
0:23seem to get past a certain point they
0:26realized what was happening is very
0:27again this so-called bad seeing
0:31basically a blurring of our image and it
0:34was because of our own atmosphere I mean
0:36our atmosphere is great is important to
0:38keeps us alive but our atmosphere lies
0:42between us and whatever object we're
0:43looking at in the space well the air the
0:47in that atmosphere is moving around and
0:49there's different pockets of air
0:51different little bodies of air that will
0:53be at different temperatures right
0:54beside each other and that means the
0:57light will actually get reflected in
0:59slightly different ways as it passes
1:00through those different pockets and as
1:02that air moves around in fact this is
1:05the idea of why you see stars twinkling
1:07at night the star is not blinking in and
1:09out but if you look go out and see star
1:12as they seem to twinkle in the sky and
1:13that's because the atmosphere is
1:16actually deflecting the light that's
1:17hitting your eye at one point it goes a
1:19slightly different angle to another and
1:21so the light seems to twinkle it's not
1:24actually twinkling from the star but
1:26it's because it's passing through the
1:28atmosphere and getting deflected
1:29slightly different angles each time and
1:31so like this image shows when the air is
1:33turbulent what we get is bad seeing and
1:36the image that we normally see gets
1:39spread out gets more blurred because the
1:41light gets reflected rather than going
1:43to a very specific point it'll get
1:45deflected a slightly different angles
1:47and the different parts of the air and
1:50so we get a blurrier image now obviously
1:55we want to account for this I mean if
1:56this example is showing this we're going
1:58at site B this site a well wait we're
2:00getting very different images at Terry
2:02different sites
2:03well that B is because the air flow can
2:06be more turbulent in some areas so we
2:09actually want to build our telescopes
2:11with that in mind
2:13in fact if you look at most images of
2:16where telescopes are built you're gonna
2:17see a lot of telescopes in the same area
2:19and it's not just astronomers being
2:21antisocial it's because certain areas
2:24are better for telescopes ideally we
2:28want them high up again remember our
2:30atmosphere is causing some problems for
2:31us it's making that light get deflected
2:34in weird ways well the higher up you are
2:37you can get above part of that
2:39atmosphere really is what our goal is we
2:41also want somewhere that's dry dry
2:45because we want the air to be less
2:48turbulent we want to be less water
2:50molecules deflecting we want a nice dry
2:53region and finally we want it to be dark
2:56which might sound silly we want it to be
3:00dark because remember my earlier
3:02conversation if you're here in Windsor
3:04we've got the nice casino lights well
3:06those are obviously not stars and really
3:08it means you can't see many stars but as
3:11soon as I get out of the city I can see
3:13more it's this idea of light pollution
3:15light pollution is from cities is from
3:20anything giving off light that actually
3:23blocks us from seeing this guy it's a
3:25term used in astronomy to talk about
3:28light from other objects making it
3:31difficult to see the light from these
3:33distant objects and that actually it
3:35plays a huge role in what we can see so
3:38when we build the telescopes they're
3:39often far away from major cities they're
3:42high up on mountains and and that's why
3:46you see a ton of them all built together
3:48because that tends to be a really good
3:49place to build so they all build even if
3:52it's from many many different countries
3:53all building telescopes in the same
3:56region but we can also try and account
4:01for this Atmospheric blurring another
4:04way so called adaptive optics we're
4:08trying to adapt to our atmospheric
4:11blurring and that was actually that
4:14earlier image I showed between the when
4:17I talk about resolution the one blurry
4:19one the nut and the other non blurry one
4:21that was fixed using adaptive optics so
4:24I mean if you go back that side or think
4:26of it you
4:27gonna see just how big of a difference
4:29it can make okay but what is happening
4:32well again our atmosphere is causing
4:35blurring but what we do is we actually
4:38are accounting for this atmosphere
4:41blurring
4:42we often will use something like a laser
4:45like this image shows and we might have
4:48something like an artificial star we use
4:51the laser to have a point of brightness
4:53that we know how it should look because
4:55we are putting that point of brightness
4:57there so we know exactly what it should
4:59look like so if it changes that change
5:03is due to the atmospheric blurring and
5:05so if we account for that the rest of
5:09the image will also be accounted for it
5:11the rest of the image that we are not
5:13artificially creating and thus we can
5:16actually account for this Atmospheric
5:18blurring and get much better resolution
5:20than is normally possible using this
5:23idea of adaptive optics actually
5:25adapting and trying to control for this
5:27atmosphere again it's often just using
5:30those mirrors those interlocking many
5:32mirrors and actually moving them around
5:34to try and control for this Atmospheric
5:37blurring