Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 61 & 62: There Are Still Big Ones Out There & From Big Dark Asteroid To Beautiful Bright Comet
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- The surface of our Moon and the more than 100 impact craters on Earth testify to the fact that celestial collisions are very rare but not impossible.
- What caused Asteroid 2013 UQ4 to turn into comet C/2013 UQ4 & have an orbit so different from most of the rest of the members of our solar system?
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:
47E – 61 – There Are Still Big Ones Out There
There are millions of moving objects in our solar system traveling in relative isolation, in trillions of cubic miles of space, as they orbit our Sun. The surface of our Moon and the more than 100 impact craters on Earth testify to the fact that celestial collisions are very rare but not impossible.
During a recent 4 day period 5 large asteroids were found in our neighborhood. The largest is about 1.5 miles in diameter and comes within 19 million miles of our planet. The second and third in size are both about a mile in diameter and will miss the Earth by wide margins. The two smallest of these asteroids are both about 1/2 mile in diameter and never come closer than 20 times the distance to our Moon. It is fortunate that none of these 5 will ever strike the Earth since they would all cause far more devastation than the object which killed 80 million trees in Russia in 1908.
Asteroid Hunters have discovered almost 900 Earth Approaching Asteroids whose impact could trigger global climate change. Fortunately none of them are on a collision course with planet Earth. Statistically we expect that there about another 100 out there. There are many more smaller ones whose impact would cause a hurricane sized area of devastation.
Humans have the ability to discover dangerous asteroids and mitigate the damage when one is found to be on a collision course with planet Earth. NASA is developing the Orion spacecraft and the Space Launch System to give us the means to visit an Earth Approaching asteroid. This is a first step.
48E – 62 – From Big Dark Asteroid To Beautiful Bright Comet
J. A. Johnson found Asteroid 2013 UQ4 as a moving point of light in the night sky. He was observing with the NASA funded Catalina Sky Survey telescope on Mt. Bigelow in Arizona. Dr. Rick Binzel and his colleagues at MIT used the NASA 3-m telescope in Hawaii to obtain a spectrum. These data suggested that this object is dark, carbon rich, and about 12 miles in diameter. At that point in its orbit, it had no discernible gas cloud or any other cometary activity. For all practical purposes it appeared to be a carbon rich asteroid. Its orbit was somewhat surprising, since its path about the Sun, is in the opposite direction to that of most of the other objects in the solar system.
About 26 weeks after its discovery, astronomers in Australia were the first to notice that this asteroid was beginning to have a fuzzy appearance. Six weeks later, Damian Peach, in England, took a stunning image showing this object is a beautiful comet with a coma and a long tail.
This type of frog to prince transformation shows that the distinction between an asteroid and a comet may change depending on the objects distance from the Sun.
Questions remain. What caused now comet C/2013 UQ4 to have an orbit so different from most of the rest of the members of our solar system? What will it be like when it returns in 470 years? Could this comet be similar to ones which are suspected of bringing water and organic materials to an ancient Earth that was dry and sterile?
For Travelers in the Night this is Dr. Al Grauer
End of podcast:
365 Days of Astronomy
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