Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 199E&200E: Smoking moon & Dead Comet
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s two stroy:
- Liquid water in Enceladus
- A potentially hazardous asteroid 2015 TB145 close approach to our Moon and then to the Earth late in 2015.
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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Transcript:
197E: Smoking moon
Not long ago the only oceans of liquid salty water humans knew about were on planet Earth.
Recent data from spacecraft and ground based telescopes indicate that the Moon’s of Jupiter, Ganymede and Europa, as well as the asteroid Ceres are likely to have oceans of liquid water.
Since 2005, the small, 313 mile diameter, icy moon of Saturn, Enceladus(N cel a dus), has been observed to have icy plumes coming from cracks near its south polar regions. When the NASA Cassini Spacecraft was programmed to fly through them, Cassini discovered that the material being ejected from Enceladus is composed of ice, water vapor and simple organic molecules.
In 2015, observations of a tiny wobble of Enceladus by the NASA Cassini mission were published in the scientific journal Icarus. “If the surface and core were rigidly connected, the core would provide so much dead weight the wobble would be far smaller than we observe it to be,” said Dr. Matthew Tiscareno (t ih s – k aa- r EH – n oh), a Cassini participating scientist at the SETI Institute and a co-author of the paper. Dr. Tiscareno continued “This proves that there must be a global layer of liquid separating the surface from the core”.
There are now 4 places in our solar system outside of mother Earth where salty water is in contact with warm rock layers. We know that on Earth life abounds around hot water vents on the sea floor. Could life exist under similar conditions on these other worlds?
198E: Dead Comet
A potentially hazardous asteroid made a close approach to our Moon and then to the Earth late in 2015. 2015 TB145 as it is now called, had come near humans six times between 1920 and 2015 but had gone unnoticed as it zipped through the night skies. On the 2015 close approach to us, the Pan-STARRS group in Hawaii found it heading towards the Sun at a speed of 23 miles/second.
On its 2015 close approach, 2015 TB145 was imaged by the RADAR at Goldstone, the Green Bank Telescope,and the Arecibo Observatory. These data show that this interesting object is about 2,000 feet in diameter and rotates about once every 5 hours. Dr. Vishnu Reddy a research scientist at the Planetary Science Institute in Tucson, Arizona said “We found that the object reflects about six percent of the light it receives from the sun”. Dr. Reddy continued “That is similar to fresh asphalt, and while here on Earth we think that is pretty dark, it is brighter than a typical comet which reflects only 3 to 5 percent of the light. Since 2015 TB145 reflects about half the light one would expect to obtain from a typical asteroid but we don’t observe the gas cloud of an active comet we are led to the conclusion that 2015 TB145 is a dead comet.
What event gave 2015 TB145 a skull like appearance and placed on its current path remains a mystery.
End of podcast:
365 Days of Astronomy
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