Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 137E & 138E: Near Venus to Past Jupiter & How Big It IsSubtitle(None)
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- About a month before my Catalina Sky Survey teammate Rik Hill spotted it, a 5 football field diameter asteroid had been almost as near to the Sun as the planet Venus.
- Dr. Arlo U. Landolt of Louisiana State University has spent more than 30 years establishing a network of standard stars around the sky which are used to calibrate the measurement of the brightness of objects in space.
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: Big thanks to our Patreon supporters this month: Rob Leeson, David Bowes, Brett Duane, Benett Bolek, Mary Ann, Frank Frankovic, Michael Freedman, Kim Hay, Steven Emert, Frank Tippin, Rani Bush, Jako Danar, Joseph J. Biernat, Nik Whitehead, Michael W, Cherry Wood, Steve Nerlich, Steven Kluth, James K Wood, Katrina Ince, Phyllis Foster, Don Swartwout, Barbara Geier, Steven Jansen, Donald Immerwahr
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 signup@365daysofastronomy.org.
Or please visit our Patreon page: https://www.patreon.com/365DaysOfAstronomy
Transcript:
137E: Near Venus to Past Jupiter
About a month before my Catalina Sky Survey teammate Rik Hill spotted it, a 5 football field diameter asteroid had been almost as near to the Sun as the planet Venus. His discovery images showed it about to cross the Earth’s orbit at a speed of 21 miles per second coming towards us. Additional observations by telescopes in Illinois, New Mexico, and Arizona showed that its 7.6 year path around the Sun will take it out to well past the planet Jupiter. This object’s orbit is highly elliptical and inclined so that it moves above and below the plane where the planets and nearly all of the other solar system objects exist. It had crossed the Earth’s orbital path moving towards the Sun about 6 weeks before it was discovered but nobody noticed it since it was faint and far away from Earth.
About 6 years from its discovery it will be once again traveling towards the Sun as it crosses the Earth’s orbit at a speed of 10 miles per second relative to us. Its path never brings it closer than about 14 times the distance to our Moon from our home planet. This is a good thing since this asteroid is 10 times larger than the object which killed 80 million trees over an 800 square mile area at Tunguska, Russia in 1908.
The asteroid hunting community has discovered nearly 1600 potentially hazardous asteroids which are larger than several football fields in diameter and come to less than 5% of the distance to the Sun from Earth. Fortunately we have not discovered any large objects like this one which are on an impact trajectory with planet Earth.
138E: How Big It Is
Asteroids are moving points of light in the night sky, which shine by reflected Sun light. The asteroid hunting community determines a new object’s orbit around the Sun by continuing to measure its changing position in the sky.
A very few of the known asteroids have come close enough to bounce RADAR beams off of or have been visited by spacecraft. In these rare cases we have direct measurements of an asteroids size and shape. For the vast majority, however, we can only estimate the size of an asteroid by comparing its brightness with nearby standard stars to determine a calibrated brightness for it.
The asteroids calibrated brightness combined with our knowledge of the Earth’s orbit, the asteroids path in space, and an assumption about the percentage of Sun light that it reflects allow us to estimate this tiny point of light’s physical size. It is also possible to determine an asteroid’s shape by repeatedly measuring it brightness as it spins on its axis and moves about the Sun.
Dr. Arlo U. Landolt of Louisiana State University has spent more than 30 years establishing a network of standard stars around the sky which are used to calibrate the measurement of the brightness of objects in space. He has conducted his observations using telescopes principally in Chile and Arizona. Dr. Landolt’s Standard Star observations are an important key to our understanding of physical processes occurring in the Universe.
The next time you hear someone state the size of an asteroid it is a safe bet that it based on Dr. Landolt’s Standard Star measurements.
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 libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes.
This show is made possible thanks to the generous donations of people like you! Please consider supporting to our show on Patreon.com/365DaysofAstronomy and get access to bonus content.
After 10 years, the 365 Days of Astronomy podcast is entering its second decade of sharing important milestone in space exploration and astronomy discoveries. Join us and share your story. Until tomorrow! Goodbye!