Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 79E & 80E: Faster Than A Speeding Bullet & An Earth Approaching Comet
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- Faster than a speeding bullet. More powerful than a locomotive. It’s not Superman, its a meteoroid.
- Richard Kowalski has discovered an Earth approaching comet that comes within 18 million miles of our home planet.
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:
79E: Faster Than A Speeding Bullet
Faster than a speeding bullet. More powerful than a locomotive. Its not Superman, its a meteoroid. Yes, a volleyball sized stoney meteoroid, which is typically traveling 15 to 60 times faster than a high powered rifle bullet, has 8 times the kinetic energy of a passenger diesel electric locomotive traveling at 100 miles per hour.
When such an object enters our atmosphere it can produce a meteor called a fireball. These meteors can be brighter than the planet Venus and be visible over hundreds of square miles. They sometimes penetrate the Earth’s atmosphere down to an altitude 30 miles or so and can produce booming sounds. Over the past few years 2,000 to 4,000 fireball events have been reported each year. This must be an underestimate, since those events which occur during the daytime or over the oceans are much less likely to be observed.
On a recent day the NASA Fireball network reported 30 fireballs. Their 15 cameras cover only a small fraction of the continental United States. Observations from several cameras are used to determine asmall object’s path through space before its impact with Planet Earth.
About 1/3 of the meteorites found on the Earth’s surface are called “falls” since they are discovered as a result of someone seeing the object fall from the sky. In fact 4 meteors from the planet Mars have been observed streaking across the sky and later pieces of them have been found on the ground. By keeping your eyes and ears open you may be able to discover a meteorite.
80E: An Earth Approaching Comet
My Catalina Sky Survey teammate Richard Kowalski has discovered an Earth approaching comet that comes within 18 million miles of our home planet. It orbits the Sun every 5 and a half years on a path that takes it from a point between the Earth and Mars out to near the planet Jupiter. Even though it is unlikely to become a bright naked eye comet or a threat to us, its discovery alerts us to the fact that there are objects like this out there.
Humans know something about approximately 5,000 of the perhaps 1 trillion comets that orbit our Sun. On a typical year one of them is likely to become bright enough to be seen with the unaided human eye.
Recently comet Siding Springs made a close approach to the planet Mars. NASA placed its three orbiting spacecraft on the opposite side of Mars as the comet’s dust trail came near. This maneuver was deemed necessary since the comet and its dust was traveling at more than 30 miles per second relative to the Red Planet.
In 1910 the Earth passed through the end of the tail of Halley’s comet. Today such an event could pose a threat to the artificial Earth satellites that we rely on, for everything, from finding a restaurant, to making a bank transaction.
The NASA funded Catalina Sky Survey operates two telescopes 24 nights per month in the Catalina mountains near Tucson, Arizona to discover Earth approaching objects. Hopefully we will be able to give a heads up in the extremely unlikely situation in which a comet is about to make a very close approach to planet Earth.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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