Download Memo to Provost regarding replacing light fixtures on Commons lawn (pdf)

MEMO
To: Provost Claudia Beversluis, Dean Uko Zylstra
From: Students of Astr384 (Prof. D. Haarsma), co-sponsored by Department of Physics and
Astronomy
Date: May 5, 2008
Re: Proposal to replace light fixtures on Commons Lawn
We propose that the 23 “china hat” style light fixtures on the Commons Lawn be replaced with
“shepherd’s crook” style light fixtures. The new fixtures would be safer, more energy efficient, and
improve the educational experience at the Calvin Observatory.
A clear night away from city lights can be an astounding thing. The light wash of the Milky Way, the
full outline of the Little Dipper, meteors streaking across the sky, bright planets and thousands of stars;
maybe even a galaxy if you know where to look. Few sights can so easily show the vastness of the
universe.
Maintaining and reclaiming dark skies is part of
creating space for the appreciation of God’s creation.
Furthermore, it is an important contribution to the
astronomy education Calvin College can offer to both
its students and its surrounding community.
Current campus lighting of pathways and parking lots
is accomplished primarily by three types of light
fixture: “cobra head,” “china hat” and “shepherd’s
crook” (shown in Figure 1). The former two types
illustrate much that is problematic with older light
fixtures installed without consideration for directional
lighting.
Fig. 1 The three main campus light fixtures (left to
right): cobra heads illuminate parking lots, china hats
light Commons Lawn and shepherd’s crooks the Chapel
patio, as well as the east side of campus.
The purpose of exterior light fixtures is to illuminate an area to help prevent crime and ease movement
at night. To do this effectively, light must travel from the light source to an object (or person) to be
illuminated, and bounce from there to an observer’s eye. Light that travels directly to the eye does not
help one see anything – this represents a “waste” of light; worse, it can detract from a person’s night
vision and hinder his or her sight of anything in dimmer light, just as when a driver or pedestrian is
temporarily blinded by oncoming headlights and finds it more difficult to see for a time after the car
has passed. This represents both a waste of the energy that produces the light and a compromise to
safety.
Both older campus light fixtures (cobra heads and
china hats) fail in this area. As illustrated in Figure
2, they send a great deal of light directly toward an
observer’s eyes (and up into the sky, where it is also
“wasted” and contributes to overall light pollution).
Fig. 2 From left to right, a cobra head light and china
hat send much of their light output directly at the camera
or upwards into the sky. In contrast, the shepherd’s
crook light has a clear cut-off in the light cone so all of
its light is directed downwards where it is useful.
In contrast, the shepherd’s crook light fixtures,
which have already been accepted as safe on the
east side of campus where they are used in the
parking lots and along the pathways around KE, the
DeVos Communications Center and the Prince
Conference Center, provide as much light at a
distance of 10 meters as do the China hats while
providing more light near the posts. They also very clearly send light downward rather than outward or
upward, putting light where it can illuminate rather than blind.
While an ultimate goal will be the upgrade of all lighting fixtures on campus, some are more urgently
needed than others. Here is where other goals – in particular, educational goals – can inform our
priorities in accordance with Calvin’s Expanded Statement of Mission, which states, “In this
community learning goes well beyond the classroom, making it possible and necessary that all campus
life promote the educational tasks.”
Light pollution greatly hinders the kind of research that can be done with Calvin’s telescope and the
general familiarity with and appreciation of the night sky that its students can achieve. Part of the
problem is our location in Grand Rapids, a city where general light pollution is a significant issue that
Calvin cannot directly improve. But the 23 china hat lights around the Commons Lawn present an
additional, more direct and significant problem – a problem which can quickly be addressed by
updating these lights to the shepherd’s crook style to match the new Chapel patio lighting. This change
would amount to a total cost of $60,500, as estimated by Lucas DeVries from Calvin’s Physical Plant.
While some of these lights have buildings or trees between them and the observatory, a few of them
shine directly at the observatory dome. They are bright enough to cast clear shadows in the
observatory, where they are responsible for two types of damage. First, glancing in their direction can
ruin one’s night vision, forcing the observer to wait several minutes before seeking faint objects or
trying to identify constellations with dimmer stars. Second, they contribute to the overall sky glow,
making it difficult to observe galaxies, nebulae or other faint objects, especially near the horizon.
These lights directly limit the ability of the observatory and the observers who work there to teach
people about the night sky. Being able to see interesting objects in the sky is crucial for all astronomy
classes as well as for those from the college and its community who visit the observatory.
Furthermore, as a point of contact between the college and the Grand Rapids community, the
observatory offers a perfect opportunity for light pollution issues to be easily communicated to others
who may go out to affect their own communities. In this way, Calvin can indirectly improve the
lighting conditions throughout the Grand Rapids by serving as leader and working model of such
improvements. Dark skies require the cooperation of a whole community. A community as large as
that of Grand Rapids will require a leader to follow if it is to change lighting to a more dark-sky
friendly arrangement. Calvin College is well-poised to be such a leader by setting up an accessible,
working system which others can learn from and imitate or improve.
The replacement of the china hat light fixtures around Commons Lawn with the newer shepherd’s
crook style lights will accomplish progress toward many of Calvin’s goals. It will use energy more
efficiently. It will improve the level of safety by allowing better vision in dim areas at night. It will
further educational goals in the areas of astronomy and light pollution issues. And it will represent one
more step toward reclaiming the dark sky that offers so much space for wonder at the magnificence of
God’s creation.