Podcaster: Dr. Al Grauer
Title: Travelers in the Night Digest: Eps.457 & 458:30 Years of FIreballs & Large and Close
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- Fireballs are meteors which become brighter than the planet Venus and can sometimes be seen in the daytime. They are caused when small space rocks occasionally exceeding 3 feet in diameter enter our atmosphere and burn up high above us.
- My Catalina Sky Survey teammate Alex Gibbs discovered 2018 GE3, which approached to less than half of the Moon’s distance from us.
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:
457-30 Years of FIreballs
Fireballs are meteors which become brighter than the planet Venus and can sometimes be seen in the daytime. They are caused when small space rocks occasionally exceeding 3 feet in diameter enter our atmosphere and burn up high above us. Fireballs that explode in mid-air are called Bolides. These small space rocks are usually not large enough to make intact to Earth, however, fragments sometimes make it to the ground for meteorite hunters to discover. Occasionally Bolides produce a loud booming sound which can break windows and do damage to trees and buildings on the ground. Dr. Alan B. Chamberlin of NASA’s Jet Propulsion Laboratory and Caltech has produced a map showing the dates, locations, and energies of the more than 700 fireball events recorded by US Government sensors, world wide, for the past 30 years. The most energetic, by a factor of 10, is the one which exploded over Chelyabinsk, Russia injuring nearly 1,500 people and raining pieces over a wide spread area in 2013. More than half of these 700 tabulated fireballs had less than 0.05%, of the energy of the Chelyabinsk Bollide and landed at random locations over the entire surface of the Earth. Many more than are recorded by US Government Sensors are witnessed by visual observers around the world. If you are lucky to see a fireball send in your report to the American Meteor Society and become a citizen scientist.
458-Large and Close
On June 30, 1908 a celestial object exploded 28,000 feet above the Tunguska river drainage area in Siberia, Russia releasing the energy of 185 Hiroshima sized atomic bombs. A man 40 miles from ground zero was hurled from his porch, trees were knocked down in a radial pattern over a 770 square mile area, and an atmospheric pressure wave from this event was recorded thousands of miles away in England. Recently a similar sized space rock made a sudden appearance before it passed very close to our Earth and Moon. The first to spot it was my Catalina Sky Survey teammate Alex Gibbs when an unusually bright, fast moving, point of light caught his attention. After Alex posted his discovery observations on the Minor Planet Center’s Near Earth Confirmation page this new object was tracked by telescopes around the world. 21h and 17 min after Alex’s discovered it this 194 diameter space rock approached to less than half of the Moon’s distance from us. 3h and 14m after that this asteroid, now known at 2018 GE3, made an even closer approach to our Moon. If 2018 GE3 would have been on an impact trajectory with planet Earth, Alex’s early discovery observations would have allowed residents of the affected area to seek shelter in hurricane resistant structures.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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