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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3E – Finding Earth Approaching Objects
Have you noticed that the closer you are to something, the faster it appears to move?
The Sun moves about 1 degree per day relative to the stars. The Moon moves about 13 degrees per day because it is much closer than the Sun.
The apparent motion of an Earth approaching object allows us to find and track it .
Using 2 telescopes near Tucson Arizona, the NASA funded, Catalina Sky Survey searches for Earth Approaching Objects. The method is to take 4 images of the same part of the sky spaced out over 45 minutes. These images are searched with computer programs to identify moving objects.
In the series of 4 images, the motion of every object identified is given a score between 0 and 100. Most asteroids are located in what is called the “main belt” between Mars and Jupiter. A score of 0 indicates the new object has an path like a main belt asteroid. A score of 100 indicates it has a motion which is very different from that of a main belt asteroid.
The motion of every object identified is compared to the orbit of the more than 500,000 known asteroids.
An unknown object is observed again in a few hours to make sure that it is real.
If it passes the reality test, and has a score greater than 50 , its position, at each of the times observed, is sent to a website at the Minor Planet Center.
Observers around the globe measure and report the new object’s position.
Data are accumulated until the new object’s orbit around the Sun is determined.
16E- Discovery of Comet P/2014 A2 (Hill)
On the night of January 8-9, 2014 Rick Hill was using the NASA funded Catalina Sky Survey telescope on Mt. Bigelow, Arizona. One of his moving object discoveries that night had a “fuzzy” looking image. He called yours truly who was operating the 60 inch telescope on nearby Mt. Lemmon for conformation. These data along with images from observers in New Mexico, Arizona, Japan, France, and Illinois showed this object has a nucleus, coma and fan shaped tail.
Comet P/2014 A2 Hill orbits the Sun once every 14.4 years on a path that goes from a bit further than Mars to out past that of Saturn. It never gets closer than a 100 million miles or so from Earth and is not likely to be a bright object in our night sky.
Comets can be beautiful naked eye objects and are named for their discoverer. From the dawn of recorded history to the present they have been viewed as objects which have brought everything from doom to the life on our planet.
Nearly 5,000 comets have been found to be orbiting our Sun. They are a small sample of those which are suspected to exist. They are a diverse collection of material left over from the early stages of our solar system.
2014 is an exciting year for comet enthusiasts. The spacecraft Rosetta will land a probe on a comet and send the data back to the Earth. You can follow its progress on the European Space Agencies website.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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