Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 563 & 564: Pre-Autumnal Harvest & Heavy Traffic
Organization: Travelers in The Night
Description: Today’s 2 topics:
- Greg Leonard was able to discover and verify 23 new Earth approaching objects (including 2019 SD1) as they passed through our celestial neighborhood.
- In the space of less than 13 hours four small space rocks zipped through the Earth-Moon neighborhood. All of them were discovered by my team.
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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563: Pre-Autumnal Harvest
On a clear but windy night, near the fall equinox, my Catalina Sky Survey teammate Greg Leonard was able to discover and verify 23 new Earth approaching objects as they passed through our celestial neighborhood. These visiting space rocks ranged from the size of an SUV to half the size of a city block. On average they had the diameter approximately the height of an 11 story building. Although three of them can come to less than 1/3 of the Moon’s distance from us none of Greg’s autumnal harvest of space rocks pose a threat to the residents of planet Earth. The one most likely to eventually enter our atmosphere is 2019 SD1.
The day after Greg spotted it, streaking through the constellation of Pisces at 15 mi/s, this 22 foot diameter space rock passed only 66,000 miles from our Moon. One hour and 11 minutes after that it came closest to Earth at a distance of less than 3/4 of the Moon’s distance from us as it escaped from the Earth-Moon system.
A space rock like 2019 SD1 enters our atmosphere every 3.3 years or so, bursts into a cloud of fragments at 106,000 feet, releases the energy of 68 tons of TNT, creates a spectacular light show, makes a sonic boom that is barely audible, and rains pieces of itself onto the surface for meteorite hunters to discover. You would be fortunate to witness such an event and if you are extremely lucky you might find a piece of such a celestial visitor to hold in your hand.
564: Heavy Traffic
In the space of less than 13 hours four small space rocks zipped through the Earth-Moon neighborhood. All of them were discovered by my team, the NASA funded, Catalina Sky Survey, before they made close approaches to our home planet. If any of these small space rocks had been on a collision course with Earth, astronomers would have had the opportunity to give us a heads up. These four tiny asteroids ranged in size from 13 to 46 feet in diameter and are no danger to humans. If any of them had entered our atmosphere they would have done nothing more than produce a light show and perhaps a small sonic boom.
In the past few years advances in telescope technology, electronic cameras, and computers running clever software are making asteroid hunters aware of just how many space rocks visit our celestial neighborhood. Residents of our planet were alerted to the importance of this research when a 66 foot diameter space rock exploded over Chelyabinsk, Russia. The resulting sonic boom injured 1,500 people mainly because of flying glass and other debris and damaged 7,200 buildings.
A Chelyabinsk sized meteor enters our atmosphere about once every 70 years or so. The chances of one exploding over a city is relatively small. Asteroid hunters are developing the capability to warn people in an affected area to avoid injury by staying away from doors and windows.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
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