Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 565 & 566: Ancient Crater & October Fest
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- The Yarrabubba Crater impact 2.29 Billion years ago that formed this crater is coincident with the end of a planet wide extremely cold period called Ice Ball Earth.
- October of 2019 was a record breaking month for my team the Catalina Sky Survey during which we discovered 240 Earth-approaching asteroids.
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:
565: Ancient Crater
In ancient times, Aboriginal people in southwestern Australia quarried fine grained rock on an ancient hill called Barlangi Rock to make very sharp tools. Dr. Timmons Erickson, a NASA scientist at the Johnson Space Flight Center, led a team which discovered that the rocks the Aborigines used to make tools were formed by the impact which produced the 46 mile diameter Yarrabubba Crater. The asteroid impact 2.29 Billion years ago that formed this crater is coincident with the end of a planet wide extremely cold period called Ice Ball Earth. This timing suggests the Yarrabubba Impactor may have vaporized thick ice sheets, blowing clouds of steam into the stratosphere.
Such a high layer of water vapor would act as a powerful greenhouse gas which in conjunction with volcanic eruptions could have caused the Earth to warm. The crater forming impact would also have spread dust over thousands of square miles, darkening the ice sheets covering the Earth which would have further enhanced the warming. Other researchers doubt that the asteroid alone could have triggered the end of such an ice age but like the idea of exploring this possibility. Over the course of history asteroid impacts have caused mass extinctions of some species while improving the chances of other living forms like mammals to flourish. It is sobering to realize that human caused global warming is causing more extinctions than any asteroid in history.
566: October Fest
October of 2019 was a record breaking month for my team the Catalina Sky Survey during which we discovered 240 Earth approaching asteroids. This diverse collection of space rocks ranged in size from one that would fit into the bed of a small pickup truck to one which is more than 1/2 mile in diameter. They average out to be 223 feet in diameter with 149 of them being larger than the meteor which exploded over Chelyabinsk Russia injuring nearly 1,500 people in February of 2013.
Fortunately none of our October discoveries will strike the Earth in the foreseeable future. 30 of this catch of space rocks can come closer to the Moon. In fact three of them can pass through the cloud of communications satellites which surround our planet.
The 30 of these most closely approaching space rocks have an average diameter of 32 feet. One of this size enters the Earth’s atmosphere once every 5 years or so, bursts into fragments at an altitude of about 122,000 feet, releases the energy of 4,000 tons of TNT, and rains fragments of itself onto the Earth’s surface for meteorite hunters to discover.
My team the Catalina Sky Survey operates 4 telescopes in the Catalina Mountains north of Tucson, Arizona, 24 nights per month when the Moon is not too bright. Our goal is to find any potentially dangerous space rock in time to mitigate the disaster it could produce. In addition we find a few comets and track the small space rocks that would produce sonic booms and light shows should they impact our home planet.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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