Podcaster: Dr. Al Grauer
Title: Travelers in the Night Digest: Eps.455 & 456:17,000 To Go, Dangerous Trio
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- Tens of millions of space rocks come closer than about 30 million miles to us and are thus classified as near-Earth objects.
- In the space of only four days, my Catalina Sky Survey teammates, Brian Africano, Alex Gibbs, and Greg Leonard, discovered three Potentially Hazardous 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.
Today’s sponsor: This episode is dedicated to Penny Wilson, my brilliant and beautiful wife who shares my love of science, math, and critical thinking. It is so much fun to have Penny walk in the door and smile when I say, did you hear the latest cosmology news! The last quarter century with you has been a blast! Your loving husband, Chauncey Wilson .
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Transcript:
455-17,000 to Go
Tens of millions of space rocks come closer than about 30 million miles to us and are thus classified as near-Earth objects. The vast majority them are tiny and produce nothing more than a spectacular light show when they enter our atmosphere. Then there are those large enough to create a destructive sonic boom such as the one which broke thousands of windows, damaged buildings, and injured nearly 1,500 people in Chelyabinsk, Russia in 2013. The most worrisome celestial neighbors are the estimated 25,000 Earth approaching asteroids that are larger than about 500 feet in diameter since the impact of one of these would cause significant damage over thousands of square miles should it enter our atmosphere over a populated area. So far asteroid hunters have found about 8,000 of these large dangerous Earth approachers leaving 17,000 more to go. At our current rate of discovery of about 115 per year, it will take 133 years to find and track 90% of them. To discover and determine the physical properties of these 17,000 dangerous neighbors in a decade, NASA has designed and proposed the NEOCam spacecraft which will be placed at the L1 stable Sun-Earth orbital location about 930,000 miles away where it’s observations will be unobstructed by the Earth and Moon. NEOCam’s infrared cameras will allow us to both discover and accurately determine the sizes of objects which enter our neighborhood giving us the ability to find them before they find us.
456-Dangerous Trio
In the space of only four days, my Catalina Sky Survey teammates, Brian Africano, Alex Gibbs, and Greg Leonard, discovered three Potentially Hazardous Asteroids. Two of them had never before been observed while the other had been lost for more than 15 years. These three large space rocks range in size from 540 to 810 feet in diameter and travel about the Sun with orbital periods of between two and three years on paths that cross the orbit of Mars and also bring them close to Earth. There are likely to be another 3,000 or so similar asteroids yet to be discovered. According to the Purdue University and Imperial College of London’s impact calculator an asteroid similar to one of these three, strikes the Earth every 40,000 years or so with an energy of several large hydrogen bombs creating a two mile diameter crater, 2,000 feet deep. If one were to strike the Earth, 100 miles away, 32 seconds after impact it would feel like a magnitude 6 earthquake. If such a large space rock struck the ocean, 25 miles offshore, in water 2,000 feet deep, about 9 minutes after the impact, the adjacent shore line would experience a tsunami wave up to 80 feet high. Searching for such a large space rock on an impact trajectory with planet Earth is what keeps my team, the Catalina Sky Survey, going to our four telescopes, 24 nights per month, when the moon isn’t too bright, in the Catalina Mountains north of Tucson Arizona.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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