Moon Has Starring Role : Partial Solar Eclipse on Tuesday Will Be the Last Visible in County Until the Next Century

At the height of the morning rush hour Tuesday,the shadow of the moon will race across Orange County in the last solar eclipse to be visible to county residents for the rest of the century.

Almost everyone in North America will have a chance to watch the moon partially eclipse the sun.

“This is a fairly good alignment for people in Orange County because the moon will cover a significant portion of the sun, whereas if you were (300 miles) farther north, it would be almost imperceptible,” said Jeff Sloan, an eclipse buff of Costa Mesa.

But, weather permitting, those watching from within a narrow band 150 miles wide, running from Baja California through southern New Mexico to northern New England, will see an even rarer sky spectacle: an annular eclipse in which the moon will blot out all but the sun’s fiery rim, creating a kind of golden solar wedding band.

Such a celestial portent in February, 1831, reportedly inspired Nat Turner, who led America’s largest slave rebellion.

Several county eclipse buffs, including John Sanford, president of Orange County Astronomers, have traveled as far as Morocco to experience the maximum effect, which will occur there at sunset. In Orange County, at the height of the partial eclipse Tuesday, almost three-fourths of the sun will be blotted out at 9 a.m.

Morning sunshine will turn to twilight. As the source of light in the sky shrinks, shadows will sharpen. In the shade of leafy trees, the ground will be dappled with hundreds of bright, dancing crescents caused by the eclipse, as overlapping leaves form a profusion of natural pinhole projectors.

“As far as astronomers in general are concerned, most eclipses are not of great scientific value, but they are of great aesthetic value and great emotional value,” said Griffith Observatory Director Edwin C. Krupp.

In all, the eclipse here will last about 2 hours and 45 minutes, beginning at 7:44 a.m. and ending at 10:29 a.m.

“You will have the thinnest crescent sun that we will see for the duration of the century,” Krupp said. “One could even say it was just like the crescent moon if it were not so bright and so dangerous to view directly.”

Astronomers warn that anyone looking directly at the eclipse risks serious eye damage unless they use proper safety filters, such as No. 14 welder’s goggles or special solar Mylar filters. Parents should keep young children from looking at the sun. Even though most of the sun’s light will be blocked, the remaining sunlight is still too intense to be viewed even briefly. The retina of the eye has no pain receptors, so the damage can happen without warning.

People can safely view the eclipse indirectly by projecting its image through a pinhole camera or by reflecting it with a pocket mirror onto a shaded wall.

Even though the eclipse will take place during rush hour, Caltrans is not worried. Spokesman Vincent Moreno said Caltrans data indicates that motorists--who appear to be willing to slow down and gawk at almost anything--actually are rather picky when it comes to rubbernecking and generally will slow only for phenomena in their immediate line of vision. The last eclipse did not cause a celestial gawkers block, he said, because commuters would have had to look up to see it.

A solar eclipse occurs somewhere around the world two to five times a year. It happens when the moon moving in its orbit around the Earth slips in between the planet and the star that lights it.

Although the sun’s diameter is about 400 times that of the moon, it also is almost 400 times farther away from the Earth, so that the two appear about the same size when viewed from Earth. Most eclipses are only partial, because the moon and sun are not perfectly in phase.

When the moon is at the farthest reaches of its orbit, it can cause an annular eclipse when it passes in front of the sun because its disk is slightly smaller than that of the sun, as seen from Earth.

The last annular eclipse visible in the region occurred two years ago--a rare late-afternoon eclipse that, for those lucky enough to experience clear skies, combined the ring of solar fire with the colors of sunset. Tuesday’s event will be the last time people in the United States will see an annular eclipse for 18 years.

Not until May 20, 2012, will the moon again appear to pass within the sun, as viewed from the Western United States, and it will be another seven years after that before the moon completely blocks the sun from view.

Darkness in the Morning Rush-hour commuters will be treated to a partial eclipse of the sun beginning at 7:44 a.m. Tuesday. In Orange County at the height of the eclipse, the sun will be 72% covered. It is the last eclipse visible in Southern California for the rest of this century.

Comparing Views:

The trademark solar ring will be visible in El Paso, which is almost directly centered on the path of annularity, Other cities along the path, such as St. Louis, will see an offset ring. The ring is visible only momentarily.

From Southern California, the sun will be about three-fourths covered, with coverage increasing toward the southernmost part of the state.

Annular vs. Total Eclipses:

In an annular eclipse, the moon is silhouetted briefly in front of the sun but is too far from Earth and can completely blot out the sun.

L.A. Eclipse Schedule:

5:56 a.m.: Sunrise

7:44 a.m.: Eclipse begins. The moon begins to move in front of the sun.

9 a.m.: Maximum eclipse. the moon covers 72% of the sun’s surface.

10:29 a.m.: Eclipse ends. Moon leaves the face of the sun.

Avoiding Eye Injury:

Any eclipse, even a total one, has the potential to cause eye injury because the visible sunlight is still far too intense even for brief glances, Here are some tips:

Create a pinhole camera by making a tiny hole in a sheet of heavy paper and using it to project the sun’s image onto a second sheet of paper held below. The image is faint but discernible.

Use a pocket mirror to reflect the sun’s image onto the shaded wall of a building.

Hang out with the experts. The Griffith Observatory will be open from 7 a.m. Specially fitted telescopes will be provided by the observatory. Sources: Griffith Observatory, Astronomy Magazine Researched by VICTORIA McCARGAR / Los Angeles Times