Sep 10th: Dangerous Comets & Dust Stories

By on September 10, 2017 in

Podcaster: Dr. Al Grauer
Travelers in the Night Digest: 320 & 321 –  Dangerous Comets & Dust Stories

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s 2 topics:

  • The real impact danger to Earth comes from comets, not asteroids. A researcher at GSFC recommends we have spacecraft ready to intercept and deflect the dangerous impactor.
  • Micrometeorites can be collected from a roof’s gutter! Jon Larsen collected many from Paris, Oslo & Berlin. & Dr. Matthew Genge of ICL studied the 0.3mm diameter rocks for a scientific paper.

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.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by — no one. We still need sponsors for many days in 2017, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at

321 – Dangerous Comets
Every year, if we are lucky, several comets can come close enough for the Sun to warm and us to see the beautiful changing dust and gas clouds around them with binoculars or our unaided eyes. So far asteroids have gotten most of the attention as dangerous celestial neighbors, however, Dr. Joseph Nuth, a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland recently pointed out “Comets can also deliver a heaping helping of calamity to Earth, and scientists and policymakers alike should start taking measures to combat the threat”. Asteroid hunters are likely to spot a large incoming asteroid long before it before it becomes a threat. Comets can come out of nowhere entering the inner solar system at a high rate of speed with little or no warning. Since humanity would not be given much lead time to deal with a deadly comet, Nuth suggests that we be ready with two spacecraft an “interceptor” and an “observer”. He feels that that these two vehicles should be ready so that if a threatening comet is discovered the “observer” could quickly be launched to make the measurements which would allow the nuclear weapon carrying “interceptor” to deflect the dangerous object which is on an impact trajectory with planet Earth. The same system could be used to deal with a large dangerous asteroid should one avoid detection by asteroid hunters and be about to strike with little advanced notice. The pair of space missions which Nuth proposes would cost less than a pair of high end military F-35 fighter jets, provide insurance against a comet strike, and teach us more about the world around us.

322 – Dust Stories
It is estimated that several hundred thousand pounds of left over particles from the formation of our solar system enters the Earth’s atmosphere every day with perhaps 10% of the of the total reaching the surface of our home planet. The individual grains of cosmic dust or micro-meteorites as they are also called range in size from the diameter of a human hair to twice the thickness of a dime.

Hundreds of beautiful and informative micro-metereotites were collected by Jon Larsen, a Norwegian JAZZ musician. Jon used a powerful magnet to discover 500 relatively large micro-meteorites from a sample of nearly 600 lbs of sediment from roof gutters in Paris, Oslo, and Berlin. His partner Dr. Matthew Genge of Imperial College in London and the rest of their team analyzed individual members of Jon’s sample and published the results of their effort in the Journal Geology. The largest micrometeorites in the Larsen sample, about a quarter of the thickness of a dime in diameter, came from dust particles which entered the Earth’s atmosphere at an amazing 7.5 miles per second. Check out the U-tube video of 62 of Jon Larsen’s micro-space rocks. They are beautiful and carry unique information about our solar system. By comparing Larsen’s modern cosmic dust particles with those from samples from rocks of various ages, scientists are re-constructing a geological history of our solar system.

You can start your own beautiful micrometeorite collection with a ZIP lock, a microscope, and a powerful magnet attached to the gutter downspout drainpipe from your roof.

End of podcast:

365 Days of Astronomy
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About Al Grauer

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