Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 125E & 126E: Bad Seeing & An Interplanetary Visitor
Organization: Travelers in The Night
Description: Today’s 2 topics:
- On a night of good seeing it is possible to spot faint Earth approaching asteroids.
- 2015 FF36 was 2.6 million miles from planet Earth and was traveling towards us at 5.5 miles per second.
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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125E: Bad Seeing
Looking at the Universe from the Earth’s surface is a bit like a scuba diver viewing our world from the bottom of a swimming pool. Don’t get me wrong. I love our atmosphere. It gives us air to breath, keeps our body’s fluids liquid, protects us from cosmic rays as well as space rocks, and performs many other functions which make life on our planet possible.
That being said the blanket of air which surrounds us makes it difficult to view objects in the Universe. On a night when the atmosphere is clear and not turbulent, the images of stars and asteroids are tiny points of light when imaged by our telescope’s cameras. Astronomers call this good seeing. On other nights it can be perfectly clear but the images of faint asteroids and stars are spread out to the point that they blend into the night sky background. This is what we call bad seeing.
On a night of good seeing it is possible to spot faint Earth approaching asteroids. On such a night members of my team, the NASA funded Catalina Sky Survey, have been known to discover more than a dozen Earth approaching asteroid candidates. On a night of bad seeing we some times don’t find any. These objects are likely to be there but we don’t detect them since the bad seeing has blended them into the darkness of the night sky.
On a recent night of observing with the NASA funded University of Arizona 60 inch telescope the seeing was so bad and I did not find a single asteroid. On the next night it was partly cloudy but the seeing was much better and I discovered 6 near Earth approaching asteroid candidates.
126E: An Interplanetary Visitor
Recently an inter-planetary visitor made a close approach to planet Earth. It is about the same size as the object which entered our atmosphere in February of 2013 injuring nearly 1500 people in Chelyabinsk, Russia.
When I first spotted this small space rock it was 2.6 million miles from planet Earth and was traveling towards us at 5.5 miles per second. After that it was tracked by telescopes in New Zealand, Germany, the Czech Republic, France, New Mexico, and Illinois. The Minor Planet Center used these data to determine its path around the Sun and gave it the name 2015 FF36. The next day it came to about 5.6 lunar distances from our home planet. It can come to within 20,000 miles of us which is closer than our communications satellites. It can also come to within 7.5 million miles of the planet Mars.
Dr. Alan Harris continues to analyze the Near-Earth asteroid population data and to calculate the number that are likely to exist in various size ranges. His work indicates that there are several million Earth approaching asteroids similar to 2015 FF36. One similar to it probably enters the Earth’s atmosphere every 40 to 50 years releasing perhaps 100,000 tons of TNT’s worth of energy.
One of the goals of the asteroid hunting community is to detect these small asteroids before they enter the Earth’s atmosphere so as to be able provide a tornado like warning to people in the effected area so that they will stay away from doors and windows.
For Travelers in the Night this is Dr. Al Grauer.
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