Telescopes are really very simple things.
They collect light. They work in a way a bit like the human eye. And you can imagine a
telescope as a giant eye. The bigger the telescope, the more light it can collect and the further
it can see. And it really is just as simple as that. So if you could build a very big
telescope, you can see very faint sources, and you can see very distant sources. Sources
at the very edge of the Universe. Things from which the light has taken over 12 billion
years to get to us.
SALT is the Southern African Large Telescope. It’s the biggest single optical infrared telescope in the Southern Hemisphere. And
I think what’s so important about the project is that it is an international collaboration.
It allows us to work with people from the United States, from Europe, from India, and
to bring those resources together to study the exciting things you can only see from
the Southern Hemisphere. For people like me, who love our continent,
SALT could be a focal point for development of scientific research in the continent, the
African continent. Because we have this fantastic first-world, first-class facility that can
attract astronomers and people who want to do astronomy in the whole African continent
or just in South Africa. SALT is built in Sutherland. And the location
was chosen because there was already another observatory existing there. Therefore, there
was also infrastructure there. I mean, you didn’t have to go and start building an
observatory from scratch.
OK, home in back again to 240, please. Nicola (?), we’ll move to 240.
This is the heart of the telescope, the primary mirror array, which consists of 91 individual mirror segments in a spherical configuration.
This is equivalent to a mirror that would be 11 meters by 10 meters in size. Building
something 11 meters in size is just, at the moment, technically impossible. So instead,
we’ve made it up from a mosaic of individual segments that collect the light and focus
it up to the instrument at the top of the telescope.
At the moment, we have two science instruments on the telescope. One of them is an imaging
camera—very similar to a video camera—which is used to make observations of varying phenomena,
where the light is varying for one reason or another, possibly on quite short time scales.
So this camera can take up to 10 frames a second. And so for things that are rapidly
varying, that’s an ideal sort of instrument. The other instrument is a spectrograph, which
splits up the light into component colors and then analyzes what we call the spectra
of an object. And so, with that instrument, you’re able to probe a lot of detail and
get a lot of physics out by looking at galaxies and stars and so on.
In any given night, we will be observing many different objects from many different programs,
which is quite different to the normal, classical way of scheduling telescopes, where an astronomer
might get a telescope to themselves for one or two nights.
OK, that should bring it to focus. All right, track time, hour and a half. Going
straight through the central supply rate, [indistinct]. All right, SALTICAM is back
on track. Say, half an hour from now, extending 45 minutes from that time on.
I query the database, and it gives me several programs which are visible at that time. In this case,
it’s only two targets. One is looking at galaxies from our Israeli collaborators. And
there’s another target looking for Kuiper Belt objects. These are small bodies, celestial
bodies on the outskirts of the Solar System. So we use SALT for science from, in astronomy,
basically from one end to the other. We can look to the very, very distant Universe, and
we can look at stars in our own galaxy. But then there are programs also which look at
objects inside our own Solar System. Here’s an example of an observation we made recently
of asteroids. These were 10-second exposures. See the asteroid moving over here? So every
frame is one SALTICAM frame from the telescope. And we just put it together, and you see the
object moving over there. There’s been a lot of science which has
hinged around having this camera, that could take very, very fast observations. And then
with the spectrograph, we were able to do quite a lot of very interesting observations
of some colliding galaxies. One bit of research which we just recently
finished was a galaxy we’ve been calling the “Bird Galaxy” because it looks like
one. There was a surprise that the whole thing was supposed to be only two galaxies. But
for the first time, really resolved, this—what we call the head of the bird—it really is
a galaxy of its own. Everything which is blue over here is new stars being born. And on
the other hand, the red bits are very obscured regions. There’s a lot of dust inside. So
with SALT, what we did, we got a spectrum, the bright things are actually emission lines.
This is actually hydrogen. And these two are nitrogen lines. And further on, you see sulfur.
And then was sodium, and oxygen, and all those. They are twisted. Means that their velocities
are different. So this part of the spectrum is actually moving away from us. And this
part of the spectrum, well, it’s coming towards us. So when you map now this structure,
on the image what we have, you can build an understanding of how this thing is moving.
The Universe is a very dynamic place. Everything is moving with respect to everything else.
And it’s very useful to have a tool to measure that movement.
As an astronomer, it’s fantastic because I have now access to one of the largest telescopes
in the world. So the type of science that I can do is just so much increased.
It’s just so many possibilities. SALT is a focal point for development of science,
research, and technology in South Africa. With SALT, we can motivate young people to
want to take up careers in science. And with SALT, we will be able to come up with exciting
discoveries that, you know, they give people a good feeling. You know, when you know that
there’s some good things happening in your country.