Podcaster: Dr. Al Grauer
Title: Travelers in the Night 543 & 544: Asteroid Zoo & Missing
Organization: Travelers in The Night
Description: Today’s 2 topics:
- In 2018 Asteroid Hunters discovered 1,839 previously unknown space rocks as they passed through our celestial neighborhood.
- Statistically, asteroid hunters are thought to have discovered 90 to 95% of the Earth approaching asteroids larger than about 3,000 feet in diameter. This group of celestial visitors is important since the impact of one of these giant space rocks could throw up enough dust and debris to disrupt human food production for a number of years.
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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In 2018 Asteroid Hunters discovered 1839 previously unknown space rocks as they passed through our celestial neighborhood. They range in diameter from one the height of an NBA basketball player to one as large as a 100 story building. More than half of these space rocks are small enough to pass under the Golden Gate Bridge. On their current paths about the Sun, 182 can come closer to us than the Moon and 3 can come closer than the communications satellites. The most dangerous member of this group is the 500 foot diameter asteroid now named 2018 LK. It orbits the Sun once very 403 days on a path that takes it very near to both Earth and Venus.
According to the Purdue University and Imperial College of London’s impact calculator, an asteroid like 2018 LK enters the Earth’s atmosphere every 11,000 years, starts to break up at an altitude of 215,000 feet, strikes the surface at a speed of 2 or 3 miles per second, and creates a crater 0.9 miles wide and 900 feet deep. If you were 100 miles from the point of impact it would feel like a 5.1 magnitude Richter Scale Earth Quake. On its current path 2018 LK can theoretically come to about a mere 1,000 miles from the Earth’s surface. However, it is not likely to do so until after 2,200 AD. Rest assured that asteroid hunters will continue to track this potentially dangerous neighbor to make sure that its path is not changed to make it a threat as it passes near the Earth, our Moon or Venus.
Statistically, asteroid hunters are thought to have discovered 90 to 95% of the Earth approaching asteroids larger than about 3,000 feet in diameter. This group of celestial visitors is important since the impact of one of these giant space rocks could throw up enough dust and debris to disrupt human food production for a number of years. Despite new cameras and larger telescopes asteroid hunters still have not found the 50 to 100 of these dangerous asteroids which are suspected to exist.
Recently we got a clue about where these missing space rocks might be hiding when the European Space Agencies Gaia (Guy ya) spacecraft, designed to measure the positions and velocities of a billion stars, discovered three asteroids with very unusual paths about the Sun. They all have orbits which are highly inclined to the plane of the solar system which contains all of the planets and most of the other asteroids. On these unusual paths these space rocks are hard to discover since they spend much of their high above or below other members of the solar system.
These high-inclination asteroids were produced by violent collisions long ago and are likely to be made of materials which give them the strength to avoid being torn apart during catastrophic encounters with other objects. They could be made of rare materials and thus may eventually prove useful to space colonists. In the meantime, asteroid hunters will need to use ground and space based telescopes to make sure that one of these rogue asteroids does not sneak up on planet Earth.
For Travelers in the Night this is Dr. Al Grauer.
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365 Days of Astronomy
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