Organization: Travelers in The Night
Description: Today’s 2 topics:
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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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367 – Future Impactor
My Catalina Sky Survey teammate Carson Fuls discovered a 33 foot diameter asteroid which has about a 1.1% chance of impacting the Earth on 569 encounters with our planet between 2045 and 2116. Its name is 2017 LD. It is on the list of the most likely objects to strike the Earth in the next hundred years as reported on NASA’s Sentry Earth Impact Monitoring table. Even so, given our current data, there is a 98.9% chance that 2017 LD will not enter our atmosphere on any of its close approaches to Earth in the next 100 years.
Carson spotted 2017 LD 3 days and 6 hours before it made a recent close approach to planet Earth when it was a bit over a million miles from him and was coming towards us at about 3 mi/sec. Unfortunately, Carson’s small space rock was bright enough for asteroid hunters to track for only 25 days out of its 601 day long path around the Sun. This lack of additional tracking data gives us a considerable uncertainty in knowing exactly where it will be in the future.
There are likely to be tens of millions of asteroids of 2017 LD’s size. One its diameter enters the Earth’s atmosphere every 10 years or so, explodes at about 3 times higher than airliners fly, and in some cases rains pieces onto the ground for us to discover. Carson’s early discovery means that if 2017 LD had been an impactor, humans would have had time to prepare for the spectacular light show that an object its size produces.
368 – Asteroid Alert
When Asteroid hunters discover a new object it is given a score ranging from 0 which means it is likely to be a distant main belt asteroid up to 100 which means that it is likely to come near to us. Each newly discovered asteroid which receives a score of 65 or greater is posted on the Minor Planet Center’s Near Earth Object Confirmation Page so that telescopes around the world can track it to estimate it’s size as well as to refine our knowledge of it’s orbit around the Sun.
NASA feeds data on each new discovery into it’s Scout software system. Scout is designed to identify those objects which are most likely to make a close approach to Earth in the very near future. It’s alert allows astronomers to access the new object’s risk of impact as well as to study it before it fades into the distance. Fortunately, asteroid hunters have not found any dangerous impacting asteroids, however, Scout’s rapid alert has enabled astronomers to measure the size, chemical composition, and rate of rotation for a number of close approaching asteroids. These data are extremely important to plan an effective response should an object be found to be on a collision course with planet Earth. For the vast majority of Earth approaching objects that asteroid hunters discover, additional observations make it less and less likely that an object will impact or even make a very close to approach to our home planet. Those few space rocks which have a tiny remote chance of coming very near to us are passed into NASA Sentry system which makes and keeps astronomers aware of nearby objects so that we do not lose track of them.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
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!