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Hello, over the last few decades astronomers have been using infrared telescopes to make visible the matter between the stars, immense clouds of dust and gas that are not hot enough to be seen with optical equipment. This is the cool universe.

Once astronomers thought of this cosmic dust has nothing more than an irritant blocking our view of the bright, important astral bodies.

But more recent research has now revealed how the universe functions as a dynamic system, and how this dust and gas play a large and vital role.

The stars themselves are formed from this cool interstellar matter, and when they eventually disintegrate their elements drift back into these clouds and materials spread across the galaxies.

Recent infrared images of these astonishing processes are now allowing us to see firsthand the means by which our planet was formed when the solar system was born.

With me, to discuss the cool universe, a Paul Merden, visiting Professor Astronomy at Liverpool John Moors University's Astronomy Research Institute, Michael Rowan Robinson, Professor of Astrophysics at Imperial College London, and Carolyn Crawford, a member of the Institute of Astronomy and a Fellow of a manual college at the University of Cambridge.

Can you summarize what astronomers thought of the universe, what it consisted of, and in particular what the lay between the stars and the planets before infrared?

Well, astronomers were really concerned with things that were tangible, especially observers they could only deal with what they saw.

So they were interested in characterizing the planets, their properties, their orbits, even discovering new asteroids, new planets, trying to work out how stars shine,

even the distribution of stars across the sky, how they structured into the galaxy.

But all of this is dictated by what they can see, what they can see with their eye, what they can see through their telescope.

And there isn't much thought given to what could lie between the stars, between the planets.

They did know there were gas clouds out there, even in the...

Why did they know that?

Well, even in the late 18th century there was a French astronomer called Charles Messier, who was compiling and cataloging a whole host of,

they were called nebulae, so this clouds in space, where he was searching for comets, new comets in the sky, and there were these little fuzzy blobs in the sky that he would repeatedly observe and confuse with the comets we started compiling catalog of them.

And some of these were very identifiably gas clouds around stars.

So they knew there were gas clouds in space, but the only manifestation they could observe are when they're close to stars and they lit up and illuminated and made visible.

We're talking about an extremely ancient science and practice of astronomy, you think of the Babylonians and on it goes through.

And they're looking all that, of course, the telescopes are getting more powerful and so on, but still as it were, the same world out there is being observed all the time until very recently.

Yes, it's still the visible light.

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