Date: August 14, 2009
Title: The Cosmos from the Outback
Podcaster: Carolyn Petersen
Organization: Loch Ness Productions (http://www.lochnessproductions.com/index2.html)
Music by GEODESIUM (http://www.geodesium.com)
Description: There’s a brand new radio array going up in the Outback Western Australia. It’s called the Murchison Wide-field Array and it’s soon going to be giving astronomers an unobstructed (radio-quiet) low-frequency portal on the universe.
Bio: Carolyn Collins Petersen is a science writer and show producer for Loch Ness Productions, a company that creates astronomy documentaries and other materials. She works with planetariums, science centers, and observatories on products that explain astronomy and space science to the public. Her most recent projects were the Griffith Observatory astronomy exhibits in Los Angeles and the California’s Altered State climate change exhibits for San Francisco’s California Academy of Sciences. She has co-authored several astronomy books, written many astronomy articles, and is currently working on a new documentary show for fulldome theaters and a vodcast series for MIT’s Haystack Observatory.
Today’s sponsor: This episode of “365 Days of Astronomy” podcast is sponsored by Loch Ness Productions, a unique multimedia production company, specializing in cosmically creative content and space music for planetariums and fulldome theaters world wide. Loch Ness Productions also works with exhibit designers, observatories, space institutes, and publishers to bring a love of astronomy, earth science, and space science to audiences everywhere. On the web at www.lochnessproductions.com.
Transcript:
Hi, I’m Carolyn Collins Petersen — the Spacewriter.
Astronomy is a multi-wavelength science, and astronomers study the sky using detectors sensitive to the entire electromagnetic spectrum.
Humans are used to seeing light in the optical part of the spectrum that is emitted or reflected from objects. That’s called “visible light.” But objects also emit energy ranging from radio and microwave — through infrared, ultraviolet, x-ray, and gamma-rays. Those aren’t visible to our eyes — and we need specialized instruments to detect them. Depending on what wavelength we select, we can study a different-looking Universe than the one we can see with our eyes alone.
For example, let’s take radio astronomy. When astronomers use radio telescopes, they’re detecting radio emissions from galaxies, pulsars, planets, and even the Sun.
Most radio astronomy is done at frequencies between 400 MegaHertz all the way up to 90 GigaHertz! But there are signals below 400 MegaHertz. They’re part of the low-frequency Universe — WAY down there — somewhere between 80 and 300 MegaHertz.
Astronomers study these low-frequency emissions from events occurring as close as Earth’s ionosphere, out to the most distant reaches of the Universe.
This low-frequency “regime” is an exciting new frontier in radio astronomy.
But, detecting low-frequency emissions requires instruments located well away from interference caused by cell phones, radio, and broadcast TV, and other communications signals. These all interfere with naturally occurring low-frequency emissions from objects and events in space.
And so, scientists interested in low-frequency astronomy are heading to the Western Australian Outback, one of the few remaining radio-quiet preserves on the planet.
There, an amazing new type of radio telescope is taking shape — called the Murchison Wide-field Array – the MWA. It’s a collection of small antennas that scan the sky and study the low-frequency Universe.
The MWA is an international project led by MIT’s Haystack Observatory near Boston in collaboration with scientists from institutions in Australia, India, and the United States.
When the system is completely built out, it will have 8,000 antennas mounted on tiles in an array spread out over a three-kilometer-wide area.
Dr. Colin Lonsdale, the director of Haystack Observatory, and one of the array partners, talked about the science that astronomers can do with MWA .
CL: Because this is such an unexplored regime, there’s a lot of new and exciting science to be done. There are three major areas of research for the MWA array. And they range from the very nearby to the far reaches of the Universe.
By looking at the way that radio waves propagate through the solar wind that fills the space between the Earth and the Sun and beyond, we can learn novel things about the way the heliospheric environment behaves. And we can learn about space weather and the way that the actions of the Sun interact with the environment of the Earth and cause things like aurorae and magnetic storms.
At the other extreme – at the farthest reaches of the Universe, further than any astronomical technique has seen so far – we can look back to the epoch when the very first stars and galaxies were forming and heating up the environment and ionizing material in the early Universe.
It turns out that hydrogen, which was abundant in those times, emits radiation at a wavelength of 21 centimeters. That radiation gets stretched out by the expansion of the Universe until by the time it gets to us, it’s right in the same frequency range that the MWA will be sensitive to. And this gives us a window into a period of the Universe that hitherto has been completely invisible to us.
CCP: The MWA will also look for transient radio events — low-frequency signals coming from such things as distant gamma-ray bursters and radio supernovae.
Even though MWA is currently under construction, astronomers are already testing the array and doing science with it at the same time.
For example, they’ve used it to measure low-frequency signals from Fornax A — a double-lobed, radio-loud galaxy with a central supermassive black hole.
The array has also looked at the very energetic core of the radio galaxy Pictor A, peered at a pulsar in our own galaxy, and even studied the disk of the Sun.
MWA is also acting as a pathfinder for the Square Kilometer Array, which should be in full operation sometime in the 2020s.
The prospects are quite exciting for the very cutting-edge science that will be done with the MWA once it’s fully up and running.
CL: With the new technologies that we have in the MWA, all of these remarkable phenomena will snap into focus. And furthermore, as these things snap into focus, many other things that we never knew about will become visible to us. So, all of us working on the project really anticipate a lot of startling surprises and remarkable new phenomena.
CCP: I can’t wait to see what MWA will show us about the Universe. To learn more about MWA, surf on over to www.thespacewriter.com/wp and click on the 365 Days of Astronomy tab.
I’m Carolyn Collins Petersen. Thanks for listening!
End of podcast:
365 Days of Astronomy
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