Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 77E & 78E: Witnessing An Asteroid Impact & Shine Little Asteroid, Shine
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- I discovered a 200’ diameter asteroid & a friend asked what it would be like to witness the impact of such an object.
- I discovered a 200 foot diameter asteroid, 2014 SC324. In the case of 2014 SC324 its brightness comes about from the fact that as it passes the Earth opposite to the Sun it appears like a little full moon in the sky.
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:
77E: Witnessing An Asteroid Impact
Recently I discovered a small asteroid with the NASA funded Catalina Sky Survey 60 inch telescope on Mt. Lemmon. This space rock is about 200 feet in diameter and will never get closer than 1/4 of the distance to the Moon. A friend asked what it would be like to witness the impact of such an object. This would be a serious event similar to what humans, 40 miles away, witnessed in Tunguska in 1908 when 80 million trees over an 800 square mile area were destroyed.
Here is some speculation fueled by calculations. As the 200 foot diameter asteroid approaches the Earth its gets brighter and brighter. Hours before the impact it would be visible in a small telescope. A few minutes before the space rock hits it will be visible at night with the human eye. A few seconds before it enters the Earth’s atmosphere it would be brighter than the planet Venus and would be visible in the daytime. At about 70 miles above the Earth’s surface it would be heated by atmospheric friction. What happens next depends on what the space rock is made of. If it is an iron meteor a significant amount will be lost but some of it could reach the surface and make a crater. If it is a stony meteor it could explode raining pieces onto the ground. If it is an icy comet it could be completely vaporized. In any event if the impact occurred over land, the super sonic boom it created, with perhaps the energy of 100 megatons of TNT, would damage trees and buildings over a wide area.
78E: Shine Little Asteroid Shine
Recently I was observing with the NASA funded Catalina Sky Survey 60 inch on Mt. Lemmon, Arizona when I discovered a 200 foot diameter asteroid, 2014 SC324. It is in an orbit around the Sun which takes it from inside our planet’s path to 60% of the way to Jupiter. This is an unusual Earth approaching space rock in that it gets bright enough to be imaged with a small telescope equipped with an electronic camera.
The brightness of an asteroid as we see it depends on its distance from the Sun and Earth, its inherent reflectivity, and the fraction of its lighted surface which faces our home planet. In the case of 2014 SC324 its brightness comes about from the fact that as it passes the Earth opposite to the Sun it appears like a little full moon in the sky. In 2014 it will pass about 1.5 lunar distances from the Earth. On other occasions it come as close as 56,000 miles to our planet. This asteroid can also make close approaches to our Moon.
2014 SC324 orbits the Sun every 2.72 years so we will be seeing it again. It is large enough to leave a hurricane sized damage area should it impact our planet. The asteroid hunting community will be keeping track of it since its Earth crossing orbit gives it a 1 in 244,000 chance of impacting the Earth after 2069.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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