Dark Skies a Local's Delight
By E.A. Barrera

Palomar Observatory

For anyone driving at night into Ramona, Julian and other areas of San Diego's rural country, it is one of the first and most pleasant changes to be seen. Slowly, the opaque night sky of the city gives way to a crisp, clear, black canvas dotted with so many stars it seems there must be something special taking place - some great celestial event that has gathered all those usually unseen portals of time and energy together.

But it is simply the normal evening view for those living outside the tents of light produced by a city's culture and industry. An urban center may have street lights and store lights and neon glittering out of a downtown, but for astronomers, environmentalists, and those who simply prefer nature's peace to man's chaos, those urban beams are a form of pollution.

Known as "sky glow," the lights can impede scientific exploration, endanger nocturnal wildlife and ruin the peace folks look for when they leave the city.

Scott Baker, an amateur astronomer for 28 years, is co-owner with his wife, Martha, of the Mountain High Bed and Breakfast and Observatory on Deer Lake Park Road in Julian.

The light pollution from local sources that hits Palomar mountain each night. Photos courtesy of Palomar Observatory

Baker said when he first started the study of astronomy he joined the San Diego Astronomy Association and did all of his observing at the club's dark-sky site at Tierra Del Sol, between Campo and Jacumba, one mile north of the border.

"When I first started going there, it was so dark, you could barely see your hand in front of your face. Now, after years of people buying the land around us and building houses, and the small Mexican town that sprang up just across the border, the skies are no longer dark.

"That's what brought me to Julian. We bought this B&B and I built my observatory, and now we are full-time residents. The sky here is dark, not as dark as Tierra Del Sol was, but now, one of the darkest skies available, outside of the Borrego desert."

According to John Harman of the British Environmental Agency (BEA), sky glow is a brightening of the night sky caused by artificial light being "scattered by small particles in the air such as water droplets and dust."

Graph showing how light pollution affects star gazing.

"The major sources of artificial light include street lighting, security lamps, advertising and display lighting, floodlights for sporting events and building illumination. Poorly fitted lights allow light to shine upwards, which causes sky glow. Some artificial light is also reflected upwards from roads, pavements and buildings," said Harmon.

David Crawford, executive director for the International Dark-Sky Association, noted that when astronomers research the galaxy, extremely faint objects can only be seen at sites free of air pollution and urban sky glow.

"For example, scientists interested in how the universe was formed may study the light of galaxies and quasars at enormous distances from Earth. These images offer information about faraway corners of the universe, helping us understand how our own world was formed. Yet, after traveling countless light-years, the light from these objects can be lost at the very end of its journey in the glare of our own sky," said Crawford.

The BEA states light pollution negatively impacts wildlife by causing migrating birds to collide with lighted buildings and creates a sense of false dawn, which can disrupt a bird's behavior.

One reason often sighted for increasing an area's lighting is the safety it can offer. But Crawford said it was a common misconception that uncovered lighting provided better light and thus more security.

"Globes and similar fixtures ...when turned on at night, they radiate not only in the direction where illumination is needed, but in all directions," noted Crawford. "More than half the light is directed upward to add to the sky glow and sideways to cause glare.

"All it takes is proper light fixtures, using only downward directed lighting and turning lights off when not in actual use," said Baker.