Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 89 & 90: Navigating the Earth/Moon Dance & Little Asteroid On An Inside Track
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- Some months the asteroid hunting community finds more than a half dozen small asteroids that pass closer to the Earth than our Moon.
- A small previously unknown asteroid immediately got my attention. I was observing with the NASA funded, University of Arizona, Catalina Sky Survey, 60 inch telescope, on Mt. Lemmon.
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:
89E: Navigating the Earth/Moon Dance
Some months the asteroid hunting community finds more than a half dozen small asteroids that pass closer to the Earth than our Moon.
Visualize the Earth and Moon to be on a playground teeter tooter. The Earth is so much more massive than the Moon, that the balance point, for this mythical teeter tooter, would be only about 3,000 miles from the center of the Earth. The Earth and Moon move about this imaginary balance point, called the center of gravity, every 27 days 7 hours and 43 minutes. The dance of these two unequal partners, causes the Moon, to move in and out from the Sun, by more than 230,000 miles as the center of gravity of the Earth-Moon system orbits the Sun.
Imagine a tiny asteroid passing between the Earth and the Moon as the two do their dance about the Sun. The Moon is about 30 times the Earth’s diameter away from us, so most of the time, one of these small objects slips between them with no problems. Very rarely an asteroid doesn’t make it. We know that space rocks strike the Earth and when we look at the Moon with a telescope we can see the many impact craters on it.
Hundreds of small objects strike the Moon every year. On March 17, 2013 a NASA telescope observed a mini-asteroid strike the Moon. If you had been watching you would have seen a star like looking spot on the Moon which lasted about a second. Perhaps one night we will discover a small asteroid on a collision course with our Moon. Lots of people would go outside to witness such an event.
90E: Little Asteroid On An Inside Track
A small previously unknown asteroid immediately got my attention. I was observing with the NASA funded, University of Arizona, Catalina Sky Survey, 60 inch telescope, on Mt. Lemmon. This asteroid was moving fast enough to make a trailed image during a 30 second exposure. It was subsequently observed by telescopes in England, Illinois, Arizona, Tennessee, and Pennsylvania. These data were used to determine its size and orbit and it was given the name of 2014 US7. This asteroid is about the size of a semi-trailer truck and orbits the Sun every 292 days.
When I first spotted 2014 US7 it was about 1.7 million miles from the Earth and it was traveling away from us at about 5 miles per second. It spends most of its time inside the Earth’s orbit and crosses it twice each year. It will make close approaches to the Earth and our Moon in 2018 and to the planet Venus in 2025.
2014 US7 is called an Aten [Ah tin] type of asteroid. The first of its type was discovered by Dr. Eleanor Key Francis “Glo” Helin in 1976. She was an American astronomer who discovered more than 800 asteroids and several comets. During her long career she made the transition from glass plates to the latest electronic detectors. She was a leader in the establishment of the Near-Earth Tracking Project which discovered more than 36,000 asteroids.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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