Organization: Travelers in The Night
Description: Today’s 2 topics:
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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475 – Lonely Fragment
My Catalina Sky Survey teammate Greg Leonard was observing with our 60 inch telescope on Mt. Lemmon, Arizona when he spotted an unknown asteroid moving at 13 miles/second through the constellation of Andromeda. Further observations by telescopes in Arizona and Croatia gathered the data which allowed scientists at the Minor Planet Center estimate it to be nearly 2,000 feet in diameter and give it the name 2018 LC3. 2018 LC3’s orbit crosses the paths of both Venus and Earth and is inclined 44 degrees to the orbital plane of the solar system where planets and most of the asteroids are located. On January 29, 2019 this tilted path will take 2018 LC3 to a very lonely place 135 million miles below the plane of the solar system. Not too worry, 253 days later 2018 LC3 will come zipping back through the plane of the solar system at a speed of 24 miles per second relative to the Sun on it’s 570 day long orbit about our star. 2018 LC3’s tilted orbit leads us to speculate that it is likely to be a relatively large fragment from a collision between two asteroids sometime in the past. We can test this idea by looking for other members of it’s family of asteroids with similar orbits and chemical compositions. Asteroid hunters will be eager to track 2018 LC3 and look for members of it’s family as it passes near Earth in 2026.
476 – Lost Comet
On June 14, 1770 Charles Messier, author of the Messier catalog, discovered comet, D/1770 L1. It was subsequently named, Comet Lexell, for astronomer Anders Johan Lexell who calculated it to have a 5.58 year orbital path about the Sun. On July 1, 1770 Comet Lexell passed about 6 times the moon’s distance from planet Earth, the closest a comet has ever come to humanity. There, Comet Lexell’s nucleus appeared to be as large as Jupiter and was surrounded by a coma of glowing gas the size of the full moon. In 1779 Comet Lexell passed very near to Jupiter, was never seen again, and considered lost. Astronomers Lexell and Laplace explained Comet Lexell’s vanishing act by arguing that Jupiter either placed it into an orbit far from Earth or completely ejected it from the solar system. In 2018 Dr. Quan-Zi Ye of Caltech and his collaborators re-analyzed Messier’s original observations and concluded that there is a 98% chance that Comet Lexell is still in our solar system. Their paper to be published in the Astronomical Journal suggests that, 2010 JL33, an Earth approaching asteroid discovered by my retired Catalina Sky Survey teammate Rik Hill has a 99.2% probability of being a fragment of long lost Comet Lexell. Perhaps additional Lexell fragments are out there.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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