dcaster: Dr. Al Grauer


Title: Travelers in the Night Eps. 639 & 640: Earth Approachers & Rocks or Rockets

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s two stroy:

  • During a recent 60 day period asteroid hunters discovered 29 space rocks as they passed closer to us than the Moon. 
  • Kacper Wierzchos discovered 2021 GM1 in the constellation of Virgo. It might be a Moon rock or a piece of Apollo mission debris.

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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639: Earth Approachers

During a recent 60 day period asteroid hunters discovered 29 space rocks as they passed closer to us than the Moon.  These  small asteroids averaged 30 feet in diameter and ranged in size from one that could fit under a basketball hoop to one the would fill the whole basketball court.  Two of the space rocks, both about the size of of a smart car, flew past us at 7 mi/s,  less than 3 Earth diameters from our home planet. One of this size enters the Earth’s atmosphere about once every 9 months, bursts into fragments at an altitude of 115,000 feet, and rains pieces which strike the Earth’s surface at 5.5 mi/s.  If the impact were to occur within your hemisphere of the night sky you would be treated to a spectacular light show.    

In 2020 eleven such fireball meteors were observed and subsequently pieces of the parent object were discovered on the surface of the Earth.  In four different cases, called hammer events,  the falling space rock struck a man made object.  For example at 8:27PM on August 24, 2020, near the village of Gatuto, Kenya, a number of people saw a bright meteor in the sky and about 5 minutes later heard 3 explosions followed by a loud bang.  One eyewitness saw one fragment strike the ground 50 feet from him as it deposited a13.5 lb fusion crusted rock into the bottom of 3 foot deep hole in his maize garden.  Nearby a woman was cooking dinner when she heard a loud noise.  When she looked into the adjacent room she discovered a hole in the metal roof and a shattered rock on the concrete floor.

640: Rocks or Rockets

Recently my Catalina Sky Survey teammate Kacper Wierzchos was asteroid hunting with our 60 inch telescope on Mt. Lemmon, AZ when he spotted a relatively bright object moving through the constellation of Virgo.  Subsequently Kacper’s discovery was tracked by 11 different observatories around the world.  Scientists used these data to calculate the new object’s orbit about the Sun, estimate its size, and give it the name 2021 GM1.  This object is curious.  Its orbital period is 1 year the same as the Earth. It is small with an estimated diameter of 6 feet or so. It is traveling at a much slower speed than most asteroids relative to Earth and it is at a distance only slightly greater than our Moon from us.  These characteristics make scientists wonder if Kacpher’s discovery, 2021 GM1, is a rock ejected from the Moon or if it is space junk from a human designed mission to the Moon.  

As of 2019 meteorite hunters had found  371 lunar meteorites in Antarctica and Africa whose chemical composition is very similar to the rocks Apollo astronauts brought back from the Moon.  The idea is that these lunar meteorites were launched from the Moon by an impact which created a half mile diameter crater on the Moon, orbited the Sun for a while, and finally fell to Earth for meteorite hunters to discover.  On the other hand 2021 GM1 could be a piece of space junk similar to the discarded Apollo 10 lunar lander “Snoopy” which was found still orbiting the Sun a few years back.  Observations which reveal how 2021 GM1 is effected by Sun light could tells us if it is a natural or man made object.

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

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