Podcaster: Dr. Al Grauer
Title: Travelers in the Night Digest: Eps. 265 & 266: Dancing with Earth & Colliding Planets
Organization: Travelers in The Night
Link : Travelers in the Night
Description: Today’s 2 topics:
- The PanStarrs group discovered 185′ diameter 2016 HO3, which co-orbits with Earth as we orbit around the Sun
- Dr. Elisa Quintana of NASA Ames has run huge computer model simulations of planetary collisions in our solar system and exoplanetary systems.
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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:
265 – Dancing with Earth
The Moon is the Earth’s long time dancing partner. This unequal pair revolve about a teeter totter type balance point which in turn orbits the Sun every 365 and a quarter days.
Sometimes the Earth-Moon dance is joined by smaller objects. In 2003 the LINEAR program, located at White Sands Missile Range in New Mexico, discovered a 65 foot diameter object which never got further than about a tenth of distance to the Sun from us for nearly 10 years. It has since left our neighborhood. Recently, the Pan-STARRS group in Hawaii discovered a 185 foot diameter asteroid which has been the Earth’s dance partner for almost a century and is likely to continue to be our companion for several more centuries. The new object, 2016 HO3, takes only 16 hours and 11 minutes longer to orbit the Sun than does the Earth itself. About half the time 2016 HO3 is closer to the Sun than we are, moves faster, and passes the Earth while the rest of the time it is further away from the Sun, moves slower than we do, and we pass it. The Earth’s gravitational pull keeps it from straying neither closer than 38 times or farther than 100 times the Moon’s distance from us. In this way, 2016 HO3 circles our home planet in a donut shaped pattern which travels with us on our yearly trip around the Sun.
Perhaps 2016 HO3 is an asteroid that humans would like to visit. Further research will reveal its size, shape, rate of spin, and chemical composition. Maybe then we can start selling tickets.
266 – Colliding Planets
In 1950 Immanuel Velikovsky published a book “Worlds In Collision” in which he drew from mythologies and religions around the world to describe a very catastrophic but not scientifically valid version of our solar system’s history.
Today scientists are replacing myths with solid evidence that violent impacts between planets, planetesimals, asteroids, and comets are very common in our galaxy. They play a vital role in the formation of solar systems which contain habitable planets.
Dr. Elisa Quintana a NASA Ames Research Center and SETI Institute Research scientist recently published a paper in the Astrophysical Journal in which she describes the results of her computer models of space collisions and their role in producing our solar system as well as those we observe to surround other stars.
Most of what we find important for Earth to harbor life: it’s spin rate, rotation, and thus it’s weather; its water and atmosphere; its core and mantle; and many other properties have been shaped by impacts and collisions. To test how these important properties of Earth came about Dr. Quintana ran two-billion year computer simulations which followed the development of a proto-planetary disk to a mature solar system like ours. In 280 such simulations, her computer calculations typically produced the presence of 3 or 4 rocky inner planets. Interestingly, more than half of her simulated solar systems contained at least one Earth-like planet. Videos made from Dr. Quintana’s calculations will give you a new appreciation of where you live.
For Travelers in the Night this is Dr. Al Grauer.
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365 Days of Astronomy
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