Full transcript
0:00thing is our quality of these images
0:03were generally starting off pretty poor
0:05I mean sure we can make them much larger
0:09but the way of link was so large we are
0:11still getting a very poor resolution in
0:14most radio telescopes and then they
0:18discovered the idea of interferometry
0:20specifically radio interferometry at
0:23first it's using it's really that idea
0:25of interference of waves what we're
0:27doing is combining the signal from more
0:30than one radio telescope so you can see
0:34this image shows a bunch of radio
0:35telescopes all together and we're
0:37combining their signals great why the
0:42thing is if you take two radio
0:45telescopes and you put them I don't know
0:49let's say a kilometer apart and you
0:52combine them using radio interferometry
0:54you get the equivalent resolution of a
0:57telescope that is one kilometer aperture
1:02or in other words it'd be like you built
1:04a one kilometer radio telescope simply
1:08by taking two telescopes and combining
1:10them as we start combining larger and
1:13larger baselines so being a bigger and
1:17bigger gap between these radio
1:18telescopes we're getting the equivalent
1:20of larger telescopes which is huge
1:23because I mean let's face it you're not
1:24gonna be able to build really a five
1:26kilometer radio telescope because you
1:28just don't have the room and that would
1:30be so expensive but if you take a bunch
1:33of telescopes and spread them out across
1:35a five kilometer distance you've got the
1:38equivalent of a five kilometer telescope
1:41in terms of resolution of course you
1:43don't get the light gathering power of a
1:45five kilometer telescope because you
1:47don't have that five kilometer nice
1:50actual telescope that would be gathering
1:53all that light but you get the
1:54equivalent resolution which is huge it
1:59all of a sudden is allowing us to make
2:00the equivalent of amazingly large
2:03telescopes look at this this is the good
2:06old very large baseline array as always
2:10great creative naming but this
2:13is a set of ten different telescopes
2:15stretching across the states the thing
2:19is its baseline is nine thousand
2:22kilometers the equivalent of building a
2:26nine thousand kilometer radio telescope
2:30the type of resolution is getting is
2:32amazing it's actually making images way
2:36better than we would ever get with a
2:37simple little radio telescope by
2:40combining a signal of two or more we are
2:43getting incredible new quality an
2:45amazing new way of looking at the
2:48universe in details we never expected it
2:51talks about this telescope lets us see
2:54the objects at the center of our own
2:56galaxy at a resolution of about 10
3:00astronomical units something as small as
3:0310 astronomical units which of course is
3:05huge from our perspective but when
3:07looking at the center of our galaxy it's
3:11allowing us to make observations and
3:12change how we see things and actually
3:15learn about the objects out there so
3:17this idea of interferometry is amazing
3:20it's allowing us better resolution than
3:22ever before and the thing is we're now
3:26starting to do with a visible light as
3:27well as we've gone better computers and
3:30could hand her hot handle higher
3:32frequency parts of the spectrum this
3:34idea of visible light interferometers
3:37have been built as well and remember we
3:40were pretty excited at the idea of
3:42building a 30 meter telescope
3:44look at this by using interferometric
3:48measures using an interferometer we can
3:52actually get the equivalent of a 400
3:56meter visible light telescope this is
4:01really letting us see things we could
4:04never have imagined in details we could
4:06never have imagined so this is huge
4:09progress in astronomy because we no
4:11longer necessarily have to build as
4:13large a telescope we can use the signal
4:17of multiple ones together now we can
4:22also look at the idea of radar astronomy
4:25not to be confused with Radio Astronomy
4:28its radar astronomy and you might be
4:31familiar with idea of radar guns that
4:34are used by the cops to tell your speed
4:36if you're going too fast you get pulled
4:39over well it's the same basic idea radar
4:43what we're doing is we're bouncing a
4:45signal off your car
4:47it comes back since we know the speed
4:49it's traveling at and how long it takes
4:51to come back we can determine how fast
4:53your car is going great well we can do
4:57the same thing to distant objects we can
4:59use this to figure out how far planets
5:02are you might remember this is how we
5:04determine what the actual unit of an
5:06astronomical unit was we looked and did
5:09radar ranging on Venus figured out how
5:12far it actually was and thus determined
5:14the actual proper distance of a Strom
5:16ostra luka unit but you can use this to
5:19also determine how high each is on a
5:21surface are if you want to look at how
5:23high a mountain on a planet is well you
5:25can figure out the distance to that
5:27mountain and the distance to the flat
5:29land we can use it to get distances to a
5:31variety of different objects and we're
5:33gonna see it as some other uses in
5:34future chapters as well but basically
5:38what we end up doing is using a radio
5:41telescope but it also has to have a
5:43transmitter normally radio telescopes
5:45have receiver they're taking this radio
5:47signals and actually receiving them in
5:50the case of radar astronomy we also have
5:53to transmit a signal bounce it off the
5:55object and then receive it back so that
5:58is important to radar astronomy we have
6:00the two components now a transmitter and
6:02a receiver and this is that huge 305
6:05meter radio telescope we can put a
6:09transmitter on it as well to do this
6:11type of signal