Podcaster: Dr. Al Grauer
Travelers in the Night Digest: Eps. 507 & 508: Eric’s Night & Quiet Sun

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s 2 topics:

  • Eric Christensen posted 16 new discoveries on the Minor Planet Center’s Near Earth Object Confirmation Page
  • Night sky measurements made at the Cosmic Campground International Dark Sky Sanctuary reveal that from 2015 to 2018 the natural night sky has declined about 30% in brightness due to the Sun has entered a relatively quiet mode

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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507- Eric’s Night

On a recent night of observing with our 60 inch telescope on Mt. Lemmon, Arizona, my Catalina Sky Survey team captain Eric Christensen posted 16 new discoveries on the Minor Planet Center’s Near Earth Object Confirmation Page. Seven of these are classified as Apollo Near Earth Asteroids because their orbits about the Sun cross the Earth’s path as they travel further from the Sun than we do. Statistically , there are likely to be several thousand Apollo asteroids larger than a half mile in diameter, 100,000 larger than a football stadium, and tens of millions as large as a house.  2018 TP5, one of Eric’s single night Apollo discoveries is about 80 feet in diameter and can come to less than 1/2 the Moon’s distance from us. It is somewhat larger than the Apollo asteroid which exploded over Chelyabinsk, Russia injuring nearly 1,500 people in February of 2013. According to the Purdue University and Imperial College of London’s Impact calculator, an asteroid the size of 2018 TP5 enters the Earth’s atmosphere every 60 years or so, makes a light show and a booming sound as it bursts into a cloud of fragments at 80,000 ft, and rains pieces of itself onto the ground. Asteroid hunters are developing the equipment and skills which enable them to predict the impact of tiny space rocks. Thus in the future you may have the opportunity to witness the light show an impactor creates and perhaps even obtain clues which will enable you too find a piece of it on the ground.

508 – Quiet Sun

The natural night sky is never completely dark due to the light from the Moon, randomly placed stars, planets, the Milky Way, light reflected by dust in the solar system, and airglow from the Earth’s atmosphere.  Night sky measurements made at the Cosmic Campground International Dark Sky Sanctuary when the Moon is below the horizon, reveal that from 2015 to 2018 the natural night sky has declined about 30% in brightness.  Amazingly this is due to the fact that the Sun has entered a relatively quiet mode, near a  minimum in the solar cycle, and thus has less ability to energize the atmosphere during the day time which in turn produces less air glow at night.  Humans have observed and recorded the presence of spots on the Sun since around 800 BC and have determined that there is an increase in the number of sunspots every 11 years producing the Solar Cycle.  During the past five years there have been the fewest number of sunspots  since 1906.  Overall solar activity in general seems to be on the decline since about 1950.  This may effect you.  From 1645 to 1715 AD the Sun’s magnetic field was so weak that it produced no Sun spots.  During this time, called the Maunder Minimum, the Earth experienced what is called the little ice age and Europe and North America were much colder than normal.  Don’t count on the decrease in solar activity to save you from human produced global warming, however something potentially important to you is happening on the Sun.

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

End of podcast:

365 Days of Astronomy
The 365 Days of Astronomy Podcast is produced by Planetary Science Institute. Audio post-production by Richard Drumm. Bandwidth donated by and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at or email us at This year we will celebrates the Year of Everyday Astronomers as we embrace Amateur Astronomer contributions and the importance of citizen science. Join us and share your story. Until tomorrow! Goodbye!

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