Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 155 & 156: Night Sky Friendly & Invisible Stuff
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- Being night sky friendly means that you only use outdoor lighting fixtures which direct light onto the ground where humans need it.
- In 1933 Fritz Zwicky suggested that the high speeds of galaxies in the relatively distant Coma Cluster are indicative of some type of invisible material which is pulling on them.
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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Transcript:
155E: Night Sky Friendly
Being night sky friendly means that you only use outdoor lighting fixtures which direct light onto the ground where humans need it and not up into the sky where it obscures the natural wonders of the Universe.
Currently more than 2/3 of the US population and more than 1/2 of the those people living in Europe cannot see the Milky Way or a meteor streaking through the night sky because of inappropriate outdoor lighting.
Amazingly enough being night sky friendly saves money and is good for business.
The economic impact of being night sky friendly has been demonstrated by Union County in the northeast corner of New Mexico. Union County, New Mexico has a population of slightly over 4,000 people. It is not on any heavily traveled tourist route, and it has a history of low visitor spending. Amazingly, Union County’s economy received a 15.6% boost when Clayton Lake State Park was certified as a Dark Sky Park by the International Dark-Sky Association. Park staff and volunteers continue to work closely with the Town of Clayton and the New Mexico State Parks system to ensure quality lighting guidelines both within the park and in the surrounding community. Being Night Sky Friendly has produced an across the board increase in local business activity in this economically depressed rural community.
Perhaps more importantly the reduced glare produced by night sky friendly lighting reduces the risk of accidents.
You can find information about becoming night sky friendly on this and the International Dark-Sky Associations websites.
156E: Invisible Stuff
In 1933 Fritz Zwicky suggested that the high speeds of galaxies in the relatively distant Coma Cluster are indicative of some type of invisible material which is pulling on them.
Nearer to home, Mercury, the planet closest to our Sun, zips along at 29 miles per second. In contrast, the much more distant Pluto orbits at a leisurely 3 miles per second . The Sun controls the orbits of these objects in this way because it has most of the mass of the solar system and is relatively compact.
In the 1970’s Dr. Vera Rubin began to measure the speeds of stars in galaxies using the Doppler shift. She expected stars orbiting at different distances from the centers of spiral galaxies to behave like the planets in our solar system since for these giant star systems the luminous mass that we observe is concentrated towards their centers. To her amazement the stars near the edge of the great galaxy in Andromeda and many other spiral galaxies are moving at speeds which indicate that these galaxies contain ten times the amount of mass that emits radiation which is visible to us. It was at this point that Dr. Rubin realized that she had discovered compelling evidence to support Zwicky’s dark matter hypothesis.
Picking up the torch, a high school student, Theodora Mautz has received the Young Astronomer Award from the Astronomical League for her investigation of the possible effect of dark matter on globular clusters orbiting our Milky Way Galaxy.
We know there is invisible stuff which has gravity. Its nature remains a mystery.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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