Podcaster: Pamela Quevillon
Title: Space Scoop: Lost and Found: The Milky Way’s ‘Missing’ Arms
Organization: Speak Easy Narration
Link : http://speakeasynarration.com ; http://unawe.org/kids/unawe1383/
Description: Space scoop, news for children.
Bio: Pamela Quevillon is a voice actress who most often lends her voice to science and science fiction content. You can find her work on the “Escape Pod” and “365 Days of Astronomy”, as well as on her site
Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by — no one. We still need sponsors for many days in 2013, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.
Transcript:
This is 365 Days of Astronomy. Today we bring you a new episode in our Space Scoop Series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
This artist’s impression shows our Galaxy, the Milky Way, as the spiral shape in the background. The massive stars referred to in the new study are indicated by red circles. The position of the Solar System is marked by a black dot and circle at the top centre. Credit: J. Urquhart et al. Background image by Robert Hurt of the Spitzer Science Center.
Astronomers cannot see what our Galaxy (which is called the Milky Way) looks like because we are on the inside looking out. But they can work out its shape by carefully studying its stars and working out their distances from us. By doing this, astronomers have reasoned that the Milky Way is spiral-shaped, with many winding arms. However, the exact number of spiral arms has been a matter of debate for many years.
In the 1950s, astronomers used radio telescopes to map our Galaxy. They focussed their observations on clouds of gas in the Milky Way in which new stars are born. Their study revealed four main spiral arms. NASA’s Spitzer Space Telescope, on the other hand, scoured the Galaxy for stars emitting infrared light. Our eyes cannot see infrared, but stars, like our Sun, shine in this light. It was announced in 2008 that Spitzer had looked at about 110 million stars, but only found two spiral arms.
Now, a 12-year study of massive stars has confirmed that our Galaxy does indeed have four spiral arms, as we believed 60 years ago. This puts to rest years of debate sparked by images taken by NASA’s Spitzer Space Telescope that showed only two arms.
“The Milky Way is our galactic home. By studying its shape we can understand how other spiral galaxies work. For example, we can find out where in these galaxies stars are born and why,” said Professor Melvin Hoare from the University of Leeds. He is one of the astronomers who rediscovered the Milky Way’s third and fourth spiral arms.
Cool Fact: Our Solar System doesn’t lie in the centre of the Milky Way, or even at the edge. We lie in the outer part of a spiral arm called the Orion Arm. It takes around 200 million years for the Solar System to orbit the galactic centre once!
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365 Days of Astronomy
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