Podcaster: Dr. Al Grauer


Title: Travelers in the Night 201E & 202E: Great Night & Jupiter’s Comet

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s two stroy:

  • Jess Johnson discovered a dozen new Earth approaching object candidates, including 2015 XY1!
  • Greg Leonard  and Rose Matheny discovered 2015 XL128.

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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201E: Great Night

On a long winter night my Catalina Sky Survey teammate Jess Johnson discovered a dozen new Earth approaching object candidates. In each case the object’s motion was significantly different from that of the thousands of main belt asteroids he observed on the same night.   Followup observations from telescopes around the world allowed astronomers to find orbital paths and estimate the sizes of ten of Jess’s discoveries.  The other two were lost and will have to be rediscovered in the future because clouds in the Earth’s atmosphere limited the followup observations of them. 

Seven of Jess’s new discoveries are Earth approaching objects which range in size from 30 to 387 feet in diameter.  None of them represent any threat to planet Earth.   

Two of them orbit the Sun along Earth like paths with a periods of about a year.  These objects may be candidates for human astronauts to visit in the future.

Three of Jess’s discoveries with further observations turned out not to be Earth approaching asteroids.  One is a main belter, one is a Mars crosser, and the other is a Centaur.

The Centaur now called 2015 XY1 orbits the Sun every 33 years between the paths of Jupiter and Saturn on a path which is highly inclined to all of the planets and most of the asteroids.  It is perhaps 30 miles in diameter. In a few million years the pulls of the giant planets will cause its orbit to change and it is likely to become a comet.  Its fate is to collide with the Sun or a planet or perhaps to be ejected into interstellar space. 

202E: Jupiter’s Comet

The giant planet Jupiter has more than twice the mass of all of the other planets, asteroids, and comets in the solar system put together.  As well as its moons Jupiter’s gravity controls the orbits of thousands of asteroids that proceed and trail it in its path around the Sun.  Jupiter also has a family of short period comets which it has collected from the Kuiper belt  beyond the orbit of the planet Neptune. The most well known of these, Comet Shoemaker-Levy met its fate in a collision with Jupiter more than 20 years ago.

A typical Jupiter family of comet’s member orbits the Sun in less than 20 years. It actively produces a gas cloud or coma for perhaps a thousand orbits around the Sun over a period of time of 10,000 years or so. What is left after the volatile material evaporates is is a small dark rocky lump or rubble pile orbiting the Sun in an elliptical orbit. 

Recently my Catalina Sky Survey teammates Greg Leonard  and Rose Matheny were using a Schmidt telescope on Mt. Bigelow, AZ when they discovered an Earth approaching object now named 2015 XL128.  Observations from telescopes in Arizona, Pennsylvania, Germany, Italy, and France indicate that this new object is relatively large and on a 6 year path around the Sun. These data suggests that 2015 XL128 may be a dormant Jupiter Family Comet.   Not too worry, 2015 XL128 never gets closer than about 13.7 million miles from planet Earth.

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

End of podcast:

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