Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 589 & 590: Defending Earth & Noctilucent Clouds
Organization: Travelers in The Night
Description: Today’s 2 topics:
- The International Asteroid Warning Network, or IWAN, has been established to link scientists who are discovering, monitoring, and physically characterizing potentially dangerous asteroids.
- Noctilucent Clouds exist at more than 50 miles above the Earth’s surface or about 4 times higher than the tops of the most intense tropical thunder storms.
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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589: Defending Earth
The International Asteroid Warning Network, or IWAN (Eye-Whan) for short has been established to link scientists who are discovering, monitoring, and physically characterizing potentially dangerous asteroids. It currently has members in Europe, Asia, South, and North America. Fortunately IWAN members have not discovered a dangerous impactor heading towards humanity. They have, however, been able to hone their skills on some of the small harmless space rocks that routinely enter and burn up in our atmosphere. For example on the night of 21/22 June 2019, the Atlas team in Hawaii discovered a small Earth approaching asteroid which was then observed by telescopes around the world.
These data were linked to a flash detected by NASA GEOS Geostationary Lightning Monitor, sound waves detected by 3 stations created to discover nuclear weapons tests, and other archival data to track the 13 foot diameter space rock as it came in from interplanetary space and exploded over the Caribbean 170 miles south of Puerto Rico. According to the Purdue University and Imperial College of London’s Impact calculator such a small space rock enters our atmosphere once every 5 months, produces a very bright fireball meteor, explodes at an altitude of 157,000 feet, and rains pieces on to the Earth’s surface. In the future the coordinated efforts of IWAN members will indicate where to search for meteorites giving you a chance to hold a 3 to 5 billion year old traveler in the night.
590- Noctilucent Clouds
Most of the clouds we see every day are located no more than 4 miles above the Earth’s Surface. Noctilucent Clouds exist at more than 50 miles above the Earth’s surface or about 4 times higher than the tops of the most intense tropical thunder storms. The first confirmed observations of Noctilucent clouds occurred in 1885 after the 1883 Krakatoa volcano blew dust high into the Earth’s atmosphere. Scientists were amazed to find that these Noctilucent Clouds continued to be observed in the summer months during astronomical twilight at latitudes above about 40 degrees in the northern hemisphere. We have learned that these clouds consist of ice crystals which condense around tiny dust particles which are produced by micrometeorites when they enter the Earth’s atmosphere from interplanetary space.
In the past 138 years, starting with the beginning of industrialization, to the present, these interesting clouds have changed from a once every 200 year phenomenon to one which is easily visible several times a year. In the 1800s these clouds were only seen in northern Europe, however recently they have become visible as far south as Colorado, Utah, and Nebraska. The reason for this dramatic increase in the numbers and range of Noctilucent Clouds is an increased level of water vapor at high altitudes human caused methane releases in the lower atmosphere. Climate change is not an abstract concept, you can see it in twilight.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
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