Dec 24th: Another Close One & Worth Tracking

By on December 24, 2017 in

Podcaster: Dr. Al Grauer
Travelers in the Night Digest: Eps. 351 & 352: Another Close One & Worth Tracking

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s 2 topics:

  • Rose Matheny is at it again! She found 12′ diameter 2017 GM that came closer than our communications satellites!
  • Greg Leonard discovered the 100-200 meter diameter PHA (Potentially Hazardous Asteroid) 2017 FD157 that can also come closer than our communications satellites. It is truly worth watching.

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.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by — no one. We still need sponsors for many days in 2017, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at

351 – Another Close One
Asteroid hunters have become aware of the many small space rocks which come near Earth because of improvements made to telescopes, cameras, and computer analysis software. Recently, my Catalina Sky Survey teammate Rose Matheny used her skills and a new camera to discover the second small space rock in 32 days which came between the communications satellites and the Earth’s surface. Rose spotted her 10 to 12 foot diameter space rock as it approached the Earth more than a million miles away with its little full moon face pointing towards us. 31 hours later, her discovery, 2017 GM, came to within 10,100 miles of Earth as it streaked by at about 11 mi/s on its way towards an encounter with Venus five and a half weeks later. It it had been on an impact trajectory with our planet, Rose’s early detection would have allowed asteroid hunters to alert humans to prepare for a spectacular light show as it exploded in our atmosphere.

There are likely to be scores of millions of tiny asteroids like 2017 GM orbiting our Sun which come close to our home planet. Approximately once a year one enters our atmosphere and explodes harmlessly about four times higher than airliners fly. Most of these space rocks originated from collisions in the asteroid belt between Mars and Jupiter. More rarely they are the result of a collision between a larger asteroid and Mars or our Moon. These interplanetary visitors have traveled between planets long before humans imagined space travel to be possible.

352 – Worth Tracking
My Catalina Sky Survey teammate Greg Leonard was observing with our team’s 60 inch telescope on Mt. Lemmon in Arizona when he discovered a relatively large space rock, 2017 FD157, which can theoretically come closer to the Earth’s surface than the communications satellites. We don’t have enough data to predict when it will make a very close approach to us. What we do know is that 2017 FD157’s orbit and that of the Earth nearly intersect coming to about Earth diameter of each other. For 2017 FD157 to make a very close approach to our planet, both of them would need to be at the position on their respective paths which are closest to each other.

If history is a guide, it is likely that additional observations will reveal that 2017 FD157 will never impact the Earth. About once every 11,000 years one of its size impacts the Earth with an atmospheric impact energy of several of large hydrogen bombs creating a crater a mile in diameter. If in an extremely unlikely turn of events, 2017 FD157, appears likely to impact our planet in the far distant future, humanity would be well served to mount a space mission to deflect it from it’s deadly course. If humans have enough time they may be able to paint it so that over time sunlight pressure would change its path otherwise a nuclear detonation or some other more aggressive move would be necessary.

For Travelers in the Night this is Dr. Al Grauer.

End of podcast:

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