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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359 – Ice World
Einstein used his theory of General Relativity to predict that the defection of light when it passed by a massive object is twice what is predicted by classical Physics. His theory was validated during a solar eclipse in 1919. Astronomers have discovered that this property of light and gravity can cause a phenomena called microlensing. When a relatively nearby star passes exactly in front of our line of sight to a much more distant star, microlensing causes a brief increase in the distant star’s brightness. If the closer star has a planet, it can cause an additional few hour increase in the distant bright star’s brightness as seen from Earth.
Recently Dr. Yossi Shvartzvald led a team which published their discovery of an Earth sized planet using microlensing in the Astrophysical Journal Letters. The newly discovered planet OGLE-2016-BLG-1195Lb orbits a small dim object about 13,000 light years from us. With only 7.8% of the Sun’s mass the new planet’s star may be a brown dwarf and not a star at all. At about the same distance from it’s star as we are from the Sun this new planet is likely to be an iceball world colder than Pluto.
NASA’s Wide Field Infrared survey Telescope when launched in the mid 2020s will be able to discover similar small planets using microlensing. Hopefully some of them will have better climates than OGLE-2016-BLG-1195Lb .
360 – Rolling in
In astronomy as in life the closer an object is to you the faster it appears to move. Recently, my Catalina Sky Survey teammate Greg Leonard witnessed this phenomena while asteroid hunting with our team’s 60 inch telescope on Mt. Lemmon, Arizona. When Greg first spotted 2017 JA it was about 900,000 miles from him coming from the direction opposite to the Sun at 9.8 mi/sec with its illuminated side facing Earth. From Greg’s point of view this small space rock was moving through the sky at a rate of about 1/3 of a moon diameter per hour. Twenty five hours later Greg’s 16 foot diameter space rock had brightened by about 50 times and was 59,000 miles from the surface of Earth. At its closet point to us 2017 JA was streaking through the sky at an amazing 63 full moon diameters per hour. Seven hours later 2017 JA was invisible to the Earth’s most powerful telescopes with it’s dark side pointing towards Earth and was about the moon’s distance from us. Like scores of millions of small space rocks, 2017 JA tours the the inner solar system orbiting the Sun on a path that brings it near Venus, Earth, our Moon and Mars.
A space rock like 2017 JA is no threat to the citizens of our planet. One like it probably enters the Earth’s atmosphere every couple of years and explodes 130,000 feet above us. If you are lucky enough to witness such a meteor you would be treated to a great light show.
For Travelers in the Night this is Dr. Al Grauer.
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365 Days of Astronomy
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