Date: June 2, 2010
Title: The Journey of Astronomy
Podcaster: Megan Argo
Description: Professor Peter Quinn, director of the International Centre for Radio Astronomy Research, describes the development of astronomy as telescopes have been improved since Galileo’s time.
Bio: Professor Peter Quinn is the director of the International Centre for Radio Astronomy Research in Perth, Western Australia.
Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by John Sandlin because a little astronomy illuminates the darkest nights.
The International Centre for Radio Astronomy Research is a joint venture between the University of Western Australia and Curtin University of Technology. Located in Perth, Western Australia, ICRAR is a collaborative centre focussing on research in astronomical science and engineering and is making important contributions to the Square Kilometre Array project. In this episode of the 365 days of astronomy, Professor Peter Quinn, ICRAR’s director, describes how our view of the universe has changed as telescopes have developed….
Astronomy is all about a journey, a journey that’s been going on since people first looked at the night sky.
In Australia the Aboriginal people have been looking at the sky for tens of thousands of years.
They’re probably the oldest and the first astronomers on the planet.
However over the last 400 years, astronomy has been on a really exciting journey starting from when we first looked at the sky through telescopes.
The Hubble space telescope, the crowning achievement, if you like, of optical astronomy in the last century.
It’s a telescope, which can look at the universe with great clarity.
This is because it’s above the Earth’s atmosphere.
It’s the prime instrument we’ve used to venture far out into the universe.
So why do we need a telescope to find out what’s out there?
We all have eyeballs and those eyeballs have a pupil, the black hole in the middle of our eye which is about 5 millimetres across.
That’s our window on the outside world.
That’s where the light from the world around us gets into our brain.
What would happen if our eye 5 times bigger?
So instead of our window to the world being 5 mm across, our window to the world would be 25 mm across.
Increasing the size of the pupil from 5 mm to 25 mm is a 5-fold increase.
But something which is 25mm in diameter, as opposed to something which is 5mm in diameter collects 25 divided by 5 squared times more light.
In other words 25 times more light can get into that very big eyeball.
So if we had a clever way of making our eyes a lot bigger then we would have a much bigger window to the universe.
And that’s exactly what Galileo did.
About 400 years ago, in 1609, Galileo was the first astronomer to use a telescope to look at the sky.
He had a very small telescope.
This small telescope, however, allowed him to collect much more light than he could normally collect just using his eyes.
In fact, he made his eyes about 25 times more powerful by using the telescope.
Galileo, with his telescope, could see many, many more stars.
All of a sudden Galileo‚Äôs universe and man‚Äôs universe became a lot richer, a lot bigger with many, many more objects to look at.
Not only did he look at the stars he looked at other familiar things like the moon.
On the moon he saw mountains, valleys and craters, things which looked very much like valleys and mountains on the earth.
And so all of a sudden the moon looked a bit like the earth.
People started to think about the moon as a place just like the earth.
And so people‚Äôs ideas about the solar system, and about other planets started to develop because they could see familiar things.
Over time the number of eyeballs we’ve used to look at the sky has increased.
In the 1700s, William Herschel built a telescope which had a diameter of about 60 cm, that’s equivalent to several tens of thousands of eyeballs.
During his life he constructed over 400 telescopes. The biggest and most famous being a reflecting telescope with a diamter of 126 cm.
On its first night of operation he discovered a new moon of Saturn.
William Herschel also discovered Uranus.
As time went on telescopes became bigger as new technology became available.
In the early 1920s Edwin Hubble observed distant galaxies using the 100 inch Hooker telescope on Mt Wilson in California.
The Hubble Space telescope is named after him as his work was the first to show that the universe is expanding.
More recently an array of very large 8 m telescopes has been built in northern Chile.
These telescopes have a collecting power in eyeball terms of more than a million.
So our eyes on the sky have actually increased with time.
Every 20 years or so the size of our telescopes doubles and our ability to probe the universe increases.
Astronomers have also developed telescopes that can detect radio waves.
Radio telescopes look very different to optical telescopes; we commonly call them dishes.
This development is an important step in astronomy because radio waves give us different information about the universe we live in.
Australia has a strong history in radio astronomy and a new radio telescope, named ASKAP is being built in the Murchison region of Western Australia.
The Murchison Radio-Astronomy Observatory may well become the home of the massive international radio telescope, the Square Kilometre Array. A project that will enable the astronomy journey to continue well into the future.
Thanks to the SPICE program of Western Australia for assisting with the production of this podcast. For more information about SPICE, log onto www.spice.wa.edu.au and for the International centre for Radio Astronomy Research visit www.icrar.org.
End of podcast:
365 Days of Astronomy
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