Organization: Travelers in The Night
Description: Today’s 2 topics:
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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447 – Nuking An Asteroid
Tonight, even though the chances are extremely slim, an asteroid hunter could find a sizable asteroid on a collision course with planet Earth. Since the Earth travels one of it’s diameters every 425 seconds advancing or delaying an impactor’s arrival, by times in this range, would cause it go in front of or behind the Earth missing humanities’ home. To effect such a change we need to know the incoming object’s physical properties and the length of time before the predicted impact. The asteroid Bennu (Ben You), which is the target of NASA’s OSIRIUS-REx spacecraft’s sample and return mission, is about 1,600 feet in diameter and has about a 1 in 24,000 chance of striking the Earth sometime in 2175. It’s properties could be typical of some of our closest celestial neighbors. The data from OSIRUS-REx’s visit will allow astronomers to calibrate data taken on an unknown much more dangerous asteroid if and when we find it. If we have decades warning, the potential impactor’s arrival time could be changed by impacting the dangerous object with a high velocity mass or if we have less time we will need to nuke it which will either blow it to bits or give it a rocket like push. NASA is designing a HAMMER spacecraft which could perform such a mission while in the meantime asteroid hunters are trying find potential impactors to give us as much lead time as possible. Stay tuned.
448 – Two PHA’s
Within the space of only 6.5 hours my Catalina Sky Survey teammate Richard Kowalski discovered two asteroids which are large enough and can come close enough for NASA to classify them as Potentially Hazardous. Both of Rich’s asteroid discoveries are about 600 feet in diameter. According to the Purdue University and Imperial College of London’s impact calculator, an asteroid of this size range enters the Earth’s atmosphere every 15,000 years or so, starts to break up at an altitude of 215,000 feet, and ultimately creates a crater a mile in diameter and 1,000 feet deep. If you were 25 miles away, 2 minutes after such an asteroid crashed into the ground you would hear a loud noise and feel a 22 mph wind. About 6 minutes after that you would experience seismic shaking equivalent to a 5.4 magnitude earthquake. Fortunately neither of Rich’s asteroid discoveries will strike the Earth or even come closer than about 9 times the distance to our Moon in the foreseeable future. Even though nearly 1,900 Earth approaching objects are classified as Potentially Hazardous, you should not worry about them since even though many of them will strike the Earth in the far distant future none will do so in the next few hundred years. What keeps my team, the Catalina Sky Survey going to our 3 telescopes in the mountains north of Tucson, Arizona, 24 nights per month, are those potentially impacting objects that we don’t know about.
For Travelers in the Night this is Dr. Al Grauer.
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365 Days of Astronomy
The 365 Days of Astronomy Podcast is produced by Astronomical Society of the Pacific. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. This year we will celebrates the Year of Everyday Astronomers as we embrace Amateur Astronomer contributions and the importance of citizen science. Join us and share your story. Until tomorrow! Goodbye!