Aug 25th: Binary Asteroids & A Lucky Friday the 13th

By on August 25, 2019 in

Podcaster: Dr. Al Grauer
Travelers in the Night Digest: 26 & 27:Binary Asteroids & A Lucky Friday the 13th

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s 2 topics:

  • The potentially hazardous asteroid Asteroid 1998 QE2
  • Asteroid Apophis passing by on April 13th, 2029.

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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15E – Binary Asteroids

Asteroid 1998 QE2 was discovered by the MIT Lincoln Near-Earth Asteroid Research program at Socorro, New Mexico. It was classified as a Potentially Hazardous Asteroid and was estimated to be about a 1/2 mile in diameter. It orbits the Sun every 3.77 years on a very elliptical path which takes it from the Earth’s orbit to out past the planet Mars.

On May 29, 2013 1998 QE2 came less than 4 million miles from Earth. It was observed by NASA’s Goldstone Solar System Radar. These data show that what Astronomers thought was a single object is really a binary asteroid. The main body is about 1.9 miles in diameter and rotates once every 5 hours. The secondary object, the asteroid’s moon, is about 1/3 of a mile in diameter and travels around its larger companion once every 32 hours.

Another binary asteroid, 2003 YT1, was discovered by Eric Christensen of the NASA sponsored Catalina Sky Survey. Radar observations reveal that 2003 YT1 is really two asteroids in orbit about a common center of gravity. 2003 YT1 is an object with a very interesting chemical composition and appears to have been ejected from the minor planet Vesta.

Approximately 1 out of 5 large Near-Earth Asteroids are really double or triple systems of objects orbiting a common center of gravity. Such double trouble objects presents a challenge if one of them were found to be heading for Earth. 

16E – A Lucky Friday the 13th

Friday April 13, 2029 will be a very lucky day for the human race.

On that day the Asteroid Apophis [uh-poh-fis] will pass about 19,400 miles above the Earth’s surface. Humans in Africa, Europe, and Asia will see a bright moving point of light. It will be about as bright as a 3rd magnitude star and be traveling at 42 degrees per hour.

Apophis was discovered June 19, 2004 by R. A. Tucker, D. J. Tholen and F. Bernardi at Kitt Peak National Observatory in Arizona. At first Apophis appeared to be on an impact trajectory with the Earth. Apophis is approximately 3 football fields in diameter and orbits the Sun every 323 days.

On that lucky Friday the 13th in 2029, Apophis will not collide with the Earth. If it did it would have an energy of 141 megatons of TNT. This is about 3 times the explosive energy of the largest hydrogen bomb ever exploded. This is also approximately 10 times the energy released in Russia in 1908 by the Tunguska [ toong-goo-skuh] event which killed 80 million trees. An impact by Apophis would likely devastate thousands of square miles of the Earth’s surface . On average we expect that such an impact event would occur every 80,000 years or so.

Astronomers refined Apophis’s orbit using RADAR data obtained in January 2013. These data eliminated the possibility that it will impact the Earth in the foreseeable future. However it remains an interesting potential destination for robotic and even manned missions.

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

End of podcast:

365 Days of Astronomy
The 365 Days of Astronomy Podcast is produced by Planetary Science Institute. Audio post-production by Richard Drumm. Bandwidth donated by and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at or email us at This year we will celebrates the Year of Everyday Astronomers as we embrace Amateur Astronomer contributions and the importance of citizen science. Join us and share your story. Until tomorrow! Goodbye!

About Al Grauer

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