Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 805 & 806: Very Close Miss & Distant PHA
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s two stories:
- During a recent 60 day period asteroid hunters observed 23 asteroids which came closer to us than our Moon. Six of them passed closer to the Earth’s surface than 22,236 miles which is the distance to our communication satellites.
- It is hard to obtain time on the 8m Gemini South Observatory telescope on Cerro Pachon in Chile and the Large Binocular Telescope with its twin 8m mirrors on Mt. Graham, Arizona since they are among the largest telescopes in the world. My Catalina Sky Survey teammate Kacper Wierzchos wrote a scientifically competitive proposal to obtain the time to track the potentially hazardous asteroid 2016 PR38 on both of these telescopes when it was near its furthest point from our Sun and thus much too faint for the telescopes asteroid hunters routinely use.
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:
Ep. 805: Very Close Miss
During a recent 60-day period, asteroid hunters observed 23 asteroids which came closer to us than our moon. Six of them passed closer to the Earth’s surface than 22,236 miles, which is the distance to the communication satellites.
Two of them were discovered by my team, the Catalina Sky Survey, two by our main competition, the Pan-STARRS group in Hawaii, and two by amateur astronomer, Gennady Borisov, using modest equipment at his observatory in Nauchene, Crimea. Borisov’s discovery of these two space rocks is no fluke, since he is an accomplished telescope maker and so far has discovered a dozen comets. I must pause to reflect on the fact that while the Catalina Sky Survey and the Pan-STARRS group in Hawaii find more than 90% of the Earth-approaching asteroids with NASA funding, Gennady Borisov supports his work by making and selling telescopes from a spot in the world which is known for war and not for astronomy.
His dedication and spirit emphasizes human choices. Back to the six space rocks that buzzed our planet, they were all small, ranging in size from that of a stuffed chair to perhaps that of an SUV automobile. Amazingly, all of them were discovered before they made their closest approach to Earth. One of Borisov’s space rocks, 2024 JN16, orbits the Sun once every 1.24 years and comes near Earth, Venus, and our moon. Asteroid hunters have already discovered a number of small space rocks before they exploded harmlessly in our atmosphere and are tooling up to be able to spot and give a warning for the next sonic boom and window-shattering space rock that is heading our way, as well as the much less likely big one.
Ep. 806: Distant PHA
It is hard to obtain time on the 8-meter Gemini South Observatory Telescope on Cerro Pechon in Chile and the Large Binocular Telescope with its twin 8-meter mirrors on Mount Graham, Arizona, since they are among the largest telescopes in the world. My Catalina Sky Survey teammate, Caspar Huerzus, wrote a scientifically competitive proposal to obtain the time to track the potentially hazardous asteroid, 2016 PR38, on both of these telescopes when it was near its furthest point from our Sun and thus much too faint for the telescopes asteroid hunters routinely use.
2016 PR38 is a several-football-field-sized diameter asteroid that crosses the orbits of both the Earth and Mars as it travels on a 25.6-month-long path about the Sun. Using these very large telescopes, Caspar was able to track 2016 PR38 when it was so far away that it took light more than 11 minutes to travel from the asteroid to Earth. Caspar’s data enable us to know 2016 PR38 will not come close to Earth again until October 8, 2048, when it will pass about 15 times the Moon’s distance from humanity.
Congress has mandated that NASA keep special track of Potentially Hazardous Asteroids, or PHAs for short. The smallest of these space rocks have diameters more than twice the height of the Statue of Liberty. If a PHA were to impact a large city, it would do damage like a nuclear explosion.
Currently, none of the more than 2,400 PHAs pose any threat to our home planet. Asteroid hunters have work to do. As statistics indicate, we have found perhaps one-third to one-half of the PHAs that may exist.
For Travelers in the Night, this is Dr. Al Grower.
End of podcast:
365 Days of Astronomy
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