Podcaster: Dr. Al Grauer
Travelers in the Night Digest: 9E & 10E: The First Pre-Impact Discovery [2008TC3] & An Asteroid with a Comet Orbit [2013JD4]

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:

  • R. A. Kowalski found 2008 TC3 in the night sky on October 6, 2008.
  • Your host, Al Grauer, discovered the 1kilometer-diameter Centaur type asteroid, 2013 JD4.

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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9E – The First Pre-Impact Discovery [2008 TC3]

Using the NASA funded Catalina Sky Survey, 60 inch telescope, operated by the University of Arizona on Mt. Lemmon, R. A. Kowalski found a moving point of light in the night sky on October 6, 2008. He reported all of his observations to the Minor Planet Center and went to bed for a well deserved rest. When he awoke, the asteroid world was excited over one of his objects, 8TA9D69. This small asteroid was on a collision course with planet Earth. During the 20 hours from its discovery, to when it exploded in the upper atmosphere, it was observed intensively by telescopes all over the world.

The force was with us in this set of events. First of all the object, later to be called 2008 TC3, came at the Earth from the midnight direction presenting its fully illuminated side towards us. Secondly it was made of dark material and exploded over a light colored desert making its fragments easily visible.

The original object was a tiny asteroid about 13 feet in diameter. It entered the Earth’s atmosphere at 29,000 miles/hour and exploded about 23 miles above the surface. Approximately 600 meteorites, totaling about 23 pounds , were found in the Sudanese desert. They included rare minerals as well as some amino acids, the building blocks of life.

2008 TC3 is the first of the two of small asteroids which astronomers have been able to find and track into our atmosphere. Samples of these impacting asteroids provide new insights into our solar system. 

10E- An Asteroid with a Comet Orbit [2013 JD4]

While searching for Earth Approaching Objects with the NASA funded Catalina Sky Survey Schmidt Telescope on Mt. Bigelow I came across an interesting, unknown moving point of light in the night sky. Follow up observations by telescopes in Chile, Arizona, Australia, Japan, Spain, Italy, and New Mexico allowed its orbit to be determined and it was given the Asteroid name 2013 JD4.

The Centaur type asteroid, 2013 JD4, is an interesting object. It takes 41.5 years to orbit the Sun on a path that takes it as close to Earth as we are to the Sun. At its maximum distance from the Sun it farther than the Planet Uranus. It has an unstable orbit and may only last a few million years on its current path. When its orbit is changed as it passes Jupiter and Saturn it may start making closer approaches to the Sun, release gases, and become a comet. 

There may be undiscovered objects like 2013 JD4 which enter the inner solar system and have relatively long orbital periods. At this point we don’t know if any of the estimated 44,000 Centaurs in the solar system will make a close approach to the Earth.

The impact of a 1KM sized object like 2013 JD4 could cause global climate change. The NASA Sponsored Catalina Sky Survey is on the look out for such objects 24 nights every month. The goal of the survey is to find any large objects at least 50 years before they get too close to the Earth.

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!

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