This time of the year, there is still a great deal of light in the sky at 9:00 in the evening. On Friday night of 8th week, a group of students met up in front of the Observatory as a pink-and-purple sunset slowly faded from the western sky. The Bald Spot seemed to glow softly in the growing twilight.
There is a student organization on campus called the Outdoor Lighting Task Force whose job it is to minimize the effects of light pollution at Carleton. Excessive street lighting interferes with birds’ migration patterns and people’s sleep cycles, and bleeds into space to make the stars much harder to see for anybody who lives in a city. The Task Force is trying to redesign Carleton’s outdoor lighting to save electricity by using LEDs and pointing light downward as much as possible so it’s used efficiently, not radiated into space. They have to strike the delicate balance between minimizing light pollution and safety. If there is insufficient lighting, people won’t be able to see where they’re going.
To educate the public about the effects of light pollution, the Task Force organized a stargazing trip out in the Lower Arb. Before we headed out, our guides pointed out the bollards around the observatory as a particularly good example of efficient lighting. The sky darkened as we walked, and some moments I was quite grateful that the path was pale gravel and my companions up ahead were making noise. But our eyes adjusted gradually to the dark, and even the middle of the Arb is never completely lightless at night. Up on a hill in the Lower Arb prairie, we could see the entire skyline free from trees, including the bright lights of nearby Northfield and even a dull glow to the north from Minneapolis-St. Paul.
Jenny Goetz ’11 handed out star maps and led us on a tour through the view. We could all recognize the Big Dipper all right, even those of us who were not particularly astronomically trained. The two stars of the dipping part led us to the North Star, and then on to the Little Dipper. Returning to the tail of the Big Dipper, Jenny showed us how to “arc to Arcturus” and “spike to Spica.” The sky was noticeably brighter and harder to see stars in the north.
And there were celestial-related snacks, of course: star-shaped cookies, Starbursts, and Milky Ways.
When we were done, we all walked back into campus in the dark. In the parking lot of the Rec Center, Jenny told us to look up. There were way fewer stars visible here, so much so that we could barely make out the constellations. That's why it's worthwhile to crash around in the Arb at night: the view is amazing.