Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 555 & 556: Dead Comet Dust & Earthly Moon Rock
Organization: Travelers in The Night
Description: Today’s 2 topics:
- The Phoenicids are a minor meteor shower which was discovered by the first Japanese Antarctic Research Expedition on December 5, 1956.
- A 3.9 Billion year old rock brought back by Apollo 14 astronauts is actually a lunar meteorite which originated on planet Earth.
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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555 – Dead Comet Dust
The Phoenicids are a minor meteor shower which was discovered by the first Japanese Antarctic Research Expedition on December 5, 1956. During this outburst, observers in New Zealand, Australia, the Indian Ocean and South Africa saw up to 100 meteors per hour coming from the constellation of Phoenix. For more than 50 years, astronomers searched for the comet which could be the source of the Phoenicids. The plot thickened when in 2003, my team the Catalina Sky Survey discovered an asteroid, 2003 WY25. This asteroid shares the orbit with the 1956 Phoenicid meteor stream as well as comet D/1819 W1 (Blanpain) which itself had been lost since it was last observed in 1819.
Dr. David Jewitt used the 2.2 m University of Hawaii telescope on Mauna Kea to discover that asteroid 2003 WY25 has a faint gas cloud coma surrounding it. Assuming that the long lost comet Blanpain, alias asteroid 2003 WY25, is the source of the Phoenicids a team of Japanese astronomers calculated that it should be possible to observe them. They split into teams who went to North Carolina where they were able to photograph 29 Phoenicids as they streaked through the sky. To spot the illusive Phoenicids for yourself plan to observe during their expected peak which occurs around December 5/6 each year.
556 – Earthly Moon Rock
In a most amazing turn of events, an international team of astronomers have published research in the Journal Earth and Planetary Science Letters which indicates that the a 3.9 Billion year old rock brought back by Apollo 14 astronauts is actually a lunar meteorite which originated on planet Earth.
The team of scientists’ hypothesis is that this tiny rock crystallized 10 to 15 miles below the Earth’s surface some 4 billion years ago during a time when both the Earth and Moon were experiencing an intense bombardment by large objects left over from the period of planet formation. It was blasted from its deep location by a giant asteroid which likely produced a crater thousands of miles in diameter.
Once on the Moon it was buried below the lunar surface by another impact. About 28 million years ago it was once again brought to the lunar surface by an object which created the 340 meter diameter Cone Crater which we see today. From there it was picked up by one of our astronauts who returned it to Earth. Although it is remotely possible that this tiny rock was formed at tremendous depths in the lunar mantle the most likely hypothesis is that it came from Earth via by an asteroid impact about 4 billion years ago.
Dr. David A. Kring, lead scientist states “It is an extraordinary find that helps paint a better picture of early Earth and the bombardment that modified our planet during the dawn of life”.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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