The page you are viewing is taken from an exhibit called MIRA: Exploring the Universe from the Central Coast.
The exhibit ran from 1 July through 24 September 2000 at the Pacific Grove Museum of Natural History.

ANSWER: A growing problem with light pollution!

A time exposure looking south from the Oliver Observing
Station shows stars and the Milky Way streaked by the
rotation of the Earth. Stars are visible to the horizon.

Lack of understanding of the nature of light and how the eye functions creates this problem. The amount of light needed to clearly see an object is called luminance. When the amount of light exceeds luminance, glare occurs, causing decreased adaptation of the eye and less vision. Light pollution is the result of glare and urban sky glow reflecting into the night, obliterating the natural light of distant objects.

Dark skies are increasingly difficult to find in the U.S. A critical factor in locating the MIRA observatory in Monterey County was the clear skies between San Francisco and Los Angeles. The light pollution in the Central Coast has increased dramatically in the last few years.)

Directing light onto the object intended to be lit, prohibiting useless upward-directed illumination of the nighttime sky, and using only the amount of light necessary should be common sense. Lighting the sky wastes energy, curtails our research into the mysteries of the Universe, and denies everyone the breathtaking beauty of the night sky. Legislation is required to protect dark skies for everyone.

In Monterey County, the worst sources of light pollution come from the cities skirting the Monterey Bay, the City of Salinas, and the correctional facilities at Soledad. Light pollution from these sources now crosses the mountains into Carmel Valley and spreads the length of the Salinas Valley. Night sky viewing at the Fremont Peak Observatory, the Oliver Observing Station on Chews Ridge, and the Weaver Student Observatory in Marina are now affected.

Recognizing that the right kind of light pointed in the right direction is adequate (and, in fact, desirable) for safety, communities across the country have begun adopting ordinances to regulate exterior lighting in order to protect dark skies.

The International Dark-Sky Association offers facts, guidance, and sample ordinances at their website, www.darksky.org. The Astronomical Society of the Central Coast and MIRA astronomers have worked to prepare a draft ordinance intended to curb light pollution of Monterey County skies before our dark sky resource is irretrievably lost.

A time exposure looking east from the Oliver Observing
Station shows the effects of light pollution over the Salinas
Valley. All but the brightest stars are obscured by the glare
of uncontrolled lighting in the Salinas Valley cities. 
(Photo courtesy of Robin Casady)

Same view from the MIRA Observatory taken before
morning twilight in 1985. The cities show as narrow
glows at the bottom; the white glow is the delicate
reflection of sunlight off interplanetary dust.
(Photo courtesy of Robin Casady)

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© 2000 MIRA