OSSD First Place Award

Junior Division
(Middle Schools; 7th and 8th Grades)

"Polluting Palomar: Effect of Skyglow on Star Visibility" (Year II)
(see abstract below)

(Photo: Julie Rucker)

From left to right are: Karen A. Hauser (Honorable Mention), Skye Aaron (Third Place),
Jeremy M. Hahn (Second Place), and Jacob J. Rucker (First Place).
(Photo from CSSF Web Site)

Advisor: R. Hunker
California Science Teacher of the Year 2004, Junior Division
Awarded by the California State Science Fair.

 

Rhoades School Teacher Honored

San Diego Union-Tribune
June 2, 2004

ENCINITAS – Roxanne Hunker, the math and science chairwoman at The Rhoades School in Encinitas, has been named California Science Teacher of the Year 2004, Junior Division, by the California State Science Fair. Hunker was previously honored as the San Diego County Science Teacher of the Year in 2002.

Of the 80 junior division students countywide who advanced to the state fair this year, 16 were from The Rhoades School, a private campus serving 300 kindergarten-through-eighth-grade students. Eighth-graders Jake Rucker and Shannon Mueller of The Rhoades School placed first for their fair entries, and eighth-graders Ray Sarno and Rebecca Chan placed second.

Hunker received the top honor partly because of the high number of her students who make it to the state competition each year.

 

 

Quantifying the Effect of Skyglow on the Visibility of Stars - Year II

Jacob Rucker
2004 California State Science Fair

 

Introduction

Southern California is a national treasure for astronomical observations because of its dry climate, clear skies, and accessibility to remote mountains. The pristine conditions at Palomar and Mt. Laguna Observatories, however, are being threatened by the increasing skyglow, a component of light pollution caused by excess light directed up into the night sky, which obscures the visibility of stars. To help the observation conditions at Mt. Palomar, the type of lighting is restricted within a 48-kilometer radius. But is this enough?

Abstract

Objective: Skyglow caused by excess light from urban centers obscures the visibility of stars and is an increasing problem for astronomical observations. This experiment determines whether the amount of skyglow can be predicted based upon the angle of observation and a site's distance from an urban center.

Materials/Methods: I used a digital (CCD) camera to take over 300 60-second time exposures in similar weather and moonlight conditions between September 2003 and March 2004 from sites around San Diego County at distances of 30, 45, 60, 75, 100, and 124 kilometers from the urban center and at angles of 45, 60, 90 (zenith), 120, and 135 degrees. The images were downloaded and converted into bmp files. I developed a custom computer program to isolate skyglow pixel values by removing CCD noise and star pixels from the images and to compute the average intensity of the skyglow pixels, from 0 to 765, for each image. Resulting intensities for each site were averaged, graphed, and compared to known functions to determine a best-fit mathematical correlation to the intensity (skyglow) as a function of a site's distance from the urban center and the angle of observation.

Results: The average intensity of the zenith images varied greatly at the six sites, from 32.4 at 30 km from the urban center to 13.6 at 45 km, 7.1 at 60 km, 5.8 at 75 km, 3.9 at 100 km, and 3.1 at 124 km. Based upon the data, I derived an approximate formula for zenith skyglow value, "S", as a function of distance, "d": S = 2.4 X 10^2 X d^-1.9 per one degree of sky. The amount of skyglow at 45 to 60-degree angles of observation averaged up to 220% more than zenith skyglow values for the same distance and up to 87% average increase at 120 to 135 degrees.

Conclusions: The amount of skyglow (S) decreased inversely with the distance (d) from the urban center, as approximated by the equation: S = 2.4 X 10^2 X d^-1.9 per one degree of sky, with significantly greater amounts of skyglow for non-zenith angles of observation both towards and away from the urban center. Applying the formula reveals that observable visible light from stars remains below 50% until over 50 km from a city the size of San Diego and does not improve to 90% visibility until over 115 km from the urban center, indicating an increasing threat to astronomical observations at the nearby Mt. Laguna and Palomar Observatories.

 

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Thank You Melles Griot

The OSSD would like to recognize and thank Melles Griot for their past and ongoing support of our Educational Outreach efforts. They have provide HeNe Lasers for both the Senior and Junior division OSSD First Place Winners at the Greater San Diego Science and Engineering Fair for over five years and continue to assist the OSSD with encouraging optic and photonic projects at the SD Science and Engineering Fair.

 

 

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