Organization: Travelers in The Night
Description: Today’s 2 topics:
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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13E – Jupiter Friend or Foe
The Earth is our home. It provides us with air, food, and water. The Sun powers all life. The role of Jupiter is less clear.
In 1994 George Wetherill performed an analysis which suggested that Jupiter has served to protect the Earth from impacts by long period comets. Recently Horner and Jones repeated these calculations using modern computing equipment. Their work supports Wetherill’s conclusions but find different results relating to near Earth asteroids and short period comets. They find that Jupiter does move objects to become Earth approaching asteroids. However, if Jupiter had 20% of its current mass then the number of these potential impactors would increase substantially.
Jupiter sends some objects our way but not so frequently enough to prevent life on Earth from recovering and adapting. The Earth was very dry when it first formed. The impact of these asteroids and comets may have provided the Earth with a blanket of water which is essential for life as we know it. Without these impacts, our planet may have turned out to be as dry as the Moon.
Mass extinctions from asteroid impacts benefit some species while eliminating others. It is likely that we humans would not be here if an asteroid had not eliminated the dinosaurs 66 million years ago.
Currently, human activity is producing extinctions on the par with an asteroid impact. How life on our planet will cope with our race remains to be seen.
14E – Fireballs
Occasionally one observes a meteor brighter than the Planet Venus which is called a fireball. Some of them can be bright enough to be seen in the day time.
NASA’s All Sky Fireball network consists of 12 cameras in groups of 2 overlapping pairs. Recently two of its cameras in New Mexico spotted a fireball as bright as the full moon. It appears to have been caused by a tiny asteroid 3 to 6 feet in diameter which entered the Earth’s atmosphere over central Texas producing a light show for residents of the Dallas / Fort Worth area.
Every year, several thousand fireballs are logged by the American Meteor Society. If you see one your report will be welcomed. You should make note of your location, the date, time, the objects position in the sky, its brightness, and how it appeared. If you are quick enough to capture the event with a cell phone camera your data will be valuable. Those bright meteors reported are likely to be a small fraction of the thousands of such events which occur daily worldwide. Fireballs are likely caused by volley ball to camping trailer size objects that enter the Earth’s atmosphere at 25,000 to more than 100,000 miles per hour and burn up several tens of miles above the Earth’s surface.
Most fireballs burn up completely, however, probably several dozen per day deposit small meteorites on the Earth’s surface. These small pieces are probably traveling at several hundred miles per hour at impact. It is not likely that one can be visually tracked to ground since it does not glow during the latter part of its trajectory.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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