Podcaster: Dr. Al Grauer
Title: Travelers in the Night Digest: 333 & 334: Whoppers & Last 19 Hours
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- Eric Christensen discovered 3,000′ diameter PHA 2017 CH1. This would be big trouble if it hit Earth. Luckily it isn’t expected to do so anytime soon.
- Richard Kowalski discovered 2008 TC3 which exploded harmlessly over Africa. Meteorites from it have been recovered. This was the first time that an asteroid was tracked before impact and then found on the ground. It was spotted 19 hours before it hit.
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:
333 -Whoppers
Recently, my Catalina Team Captain Eric Christensen discovered a potentially hazardous 3,000 foot diameter asteroid, 2017 CH1. Asteroid hunters are discovering less than one asteroid of this size or greater per month. Eric’s discovery, 2017 CH1, has an orbit which can bring it to about twice the Moon’s distance from planet Earth. Although it will not come anywhere near Earth in the foreseeable future, asteroid hunters will continue to monitor 2017 CH1’s orbit to make sure that it remains no threat to planet Earth.
Asteroid hunters have discovered more than 870 Earth approaching asteroids which are more than one km or about 3,300 feet in diameter. It is important that asteroid hunters find and track the approximately 90 asteroids remaining in this size range which have not been discovered, since the tiny chance of the once every 500,000 years impact of one of them, would have a global damaging effect on weather and agriculture. Using some mid range values it is estimated that the impact of a 1 KM object could release more energy than 800 large hydrogen bombs and produce a crater 8 or 9 miles in diameter. The US Congress has directed NASA to find and track one Km or larger near Earth asteroids which is the reason they are a special focus of NASA’s Planetary Defense Coordination Office. Fortunately none of these large celestial objects are heading our way. Asteroid hunters will continue to scan the sky for any others that might exist.
334 -Last 19 Hours
2008 TC3 was discovered by my Catalina Sky Survey teammate Richard Kowalski on October 6, 2008. It is the only asteroid which humans have tracked traveling through space, have seen exploding in our atmosphere, and have been able walk up to pieces on the Earth’s surface.
2008 TC3 was about 13 feet in diameter and would have weighed in at about 176,000 pounds if it were on the surface of our planet. It is likely that two or three small asteroids like 2008 TC3 enter the Earth’s atmosphere every year and explode 20 miles or so above the surface of our planet releasing the energy of several thousand pounds of TNT.
When Richard discovered it, this small space rock was about 1.3 times the Moon’s distance from him traveling towards our planet from the direction opposite to the Sun with its little full moon face pointing towards the Earth. 24 hours previously it was bright enough to have been spotted if someone had been looking in it’s direction. 18 hours after Kowalski’s first data point 2008 TC3 had brightened more hundred times before becoming invisible when it entered the Earth’s shadow 57 minutes before it exploded in the Earth’s atmosphere.
My team, the Catalina Sky Survey has recently installed 100 million pixel cameras on both of our telescopes. We hope to be able use them to discover impacting space rocks like 2008 TC3 and maybe even be able to tell you where to find pieces of them on the ground.
End of podcast:
365 Days of Astronomy
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