Podcaster: Dr. Al Grauer
Title: Travelers in the Night Digest: Eps. 269 & 270: Gamma Ray Eyes & Space Opals
Organization: Travelers in The Night
Link : Travelers in the Night
Description: Today’s 2 topics:
- If you could see in Gamma Rays you could see 2 huge things in the night sky that you can’t see with normal eyes.
-
Professor Hilary Downs of University College London has found opal in EET 83309, a meteorite from Antarctica.
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Bio: Dr. Al Grauer is currently an observing member of the Catalina Sky Survey Team at the University of Arizona. This group has discovered nearly half of the Earth approaching objects known to exist. He received a PhD in Physics in 1971 and has been an observational Astronomer for 43 years. He retired as a University Professor after 39 years of interacting with students. He has conducted research projects using telescopes in Arizona, Chile, Australia, Hawaii, Louisiana, and Georgia with funding from NSF and NASA.
He is noted as Co-discoverer of comet P/2010 TO20 Linear-Grauer, Discoverer of comet C/2009 U5 Grauer and has asteroid 18871 Grauer named for him.
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Transcript:
269 -Gamma Ray Eyes
If you woke up tomorrow with gamma ray eyes things would look very different. Geology would come to life as you peered into the Earth and became aware of the various minerals it contains. Gamma rays coming from stars, supernovae, pulsars, and black holes would create a fog extending over all of the sky.
Perhaps the strangest sight of all to your gamma ray eyes would be the Milky Way. Amazingly, your view our galaxy would be dominated by two giant bubble like structures which are invisible to real human eyes. These bubbles of gamma ray emission have a diameter a quarter of the size of the Milky Way’s disk and stretch across about half of the sky. Imagine a view of the Milky way the size of a DVD disk with tangerine sized bubbles of gamma ray emission touching each side of its central hole.
By viewing a distant quasar through the one of the giant bubbles, the Hubble Space telescope was able to measure the speed and composition of the two million mile per hour wind which is pushing the bubbles into intergalactic space. The silicon, carbon, and aluminum atoms the HST detected were created inside of massive ancient stars near the galactic center.
Astronomers think that these bubbles were created by either an incredible burst of star formation or a major burp from a supermassive black hole at the center of the Milky Way. Unlike many of the events in the Universe which occurred in the distant past these bubbles were created only about 2 million years ago at about the time our ancestors were learning how to walk upright on planet Earth.
270 – Space Opals
Opal, the national gemstone of Australia, is silica, the most common ingredient of sand, with a number of water molecules attached to it. On Earth Opal forms when water evaporates from a slurry of sand and water which is deposited repeatedly in a crack or fissure in a rock over a long period of time. The resulting opal may contain from 3 to 21% water by weight.
Professor Hilary Downes of Birkbeck College London headed up a team which discovered Opal in a meteorite which was found in Antartica. Previous to their work the only known extra-terrestrial Opal consisted of a few crystals which were found in a meteorite from Mars.
The Antarctic meteorite that Professor Downes and her team studied, EET 83309, is made up of thousands of small pieces of rocks and minerals. This space rock was created by collisions between objects from various parts of our solar system. Some of them are likely to have been carrying large amounts of water ice. The Downes team found solid evidence that the opal was formed before their sample left the surface of the parent asteroid, traveled through space, and was recovered by humans on the Antarctic ice sheet.
Professor Downes concludes “This is more evidence that meteorites and asteroids can carry large amounts of water ice. Although we rightly worry about the consequences of the impact of large asteroids, billions of years ago they may have brought the water to the Earth and helped it become the world teeming with life that we live in today.”
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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