Podcaster: Dr. Al Grauer


Title: Travelers in the Night Eps.  131E & 132E: Busy Little One & One Of A Million

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s 2 topics:

  • Rik Hill discovered 2015 GU, a 20 foot diameter asteroid orbits the Sun every 3 years.
  • I (Al Grauer) discovered faint, 60 foot diameter 2015 GB.

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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131E: Busy Little One

Recently my Catalina Sky Survey teammate Rik Hill discovered an asteroid about the size of a luxury sedan which cruises about the inner solar system.

When Hill found it this tiny space rock was about 750,000 miles away and was traveling at 7 miles per second towards us. The day after its discovery this small asteroid passed between the Earth and Moon. During this period of time it was observed by telescopes in New Zealand, Japan, Estonia, and Hungary. The Minor Planet Center gave it the name 2015 GU. 

This 20 foot diameter asteroid orbits the Sun every 3 years. We don’t know how long ago it was placed into this orbit.  If we could get a piece of it we could read its internal clocks. For example, by analyzing fragments of the space rock which entered our atmosphere over Chelyabinsk, Russia we know it had collisions 30 million and 2 million years ago which put it on a path to impact planet Earth.

Scientists at JPL and NASA have calculated this small asteroids path through space. From 1902 till the time of its discovery it made close approaches 14 times to Earth, 4 to Mars, and once to our Moon. Between 2023 and 2129 it will make 9 close approaches to planet Earth.

It is unlikely that 2015 GU will enter our atmosphere. If it did it would probably disintegrate before reaching the surface releasing the energy of several thousand tons of TNT. In the meantime 2015 GU will continue to travel the inner solar system until it collides with another object in the far distant future.

132E: One Of A Million

Recently I was observing with the NASA funded Catalina Sky Survey 60 inch telescope on Mt. Lemmon when the computer identified a faint fast moving object in the night sky. Not being sure it was real I scheduled followup observations. About an hour later the second set of observations showed that it is a real object. On the next two nights this small space rock was observed by telescopes near Westfield, Illinois and on Kitt Peak in Arizona. These observations allowed the Minor Planet Center to determine an orbit and a tentative size. It was given the name 2015 GB.

2015 GB is about 60 feet in diameter. Amazingly, the equipment was able to detect it when it was over 4 million miles away and traveling towards Earth at more than 7 miles/second. Six days earlier it had been about half that distance away from us but nobody had spotted it. At some point in the future the motion of this small asteroid and our planet will allow it to come to about 150,000 miles from us.

Dr. Al Harris continues to study the properties and discovery statistics of the near Earth  
asteroid population. His work indicates that there perhaps as many as 10 million space rocks like 2015 GB which come close to Earth. So far we have have discovered only a few thousand of them. The problem is that, most of the time, they are too faint to be detected by our telescopes.

We hope to find ones this size that are on an impact trajectory with planet Earth so as to be able to warn people to stay away from doors and windows. 

For Travelers in the Night this is Dr. Al Grauer.

End of podcast:

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