Celestial Commuter Show : Tuesday’s Solar Eclipse Will Be Last of the Century Here

At the height of the morning rush hour Tuesday, the shadow of the moon will race across Los Angeles in the last solar eclipse visible here for the rest of the century.

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

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.

At the height of the partial eclipse in Los Angeles on Tuesday, almost four-fifths 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 even to be viewed briefly. The retina of the eye has no pain receptors, so the damage can happen without warning.

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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 that 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 occasionally slips in between the planet and the central star that lights it.

Although the sun is about 400 times larger than 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 partial ones because the moon and the sun are not always 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

Late rush-hour commuters will be treated to a partial, or annular, eclipse of the sun beginning at 7:44 a.m. Tuesday. In Los Angeles at the height of the eclipse, the sun will appear to be 72% covered. It will be the last eclipse visible in Southern California for the rest of this century.

Comparing Views * The trademark solar halo 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 four-fifths 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 to completely cover the sun.

Total eclipses are spectacular, with a very dark sky and flaring solar corona. These occur when the moon is closer to 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, the Los Angeles Astronomical Society and local clubs. Sources: Griffith Observatory, Astronomy magazine

Where the Eclipse Can Be Seen

* Weather permitting, the eclipse will be visible across North America in a path moving from southwest to northeast.

* The moon’s shadow will take one hour and 40 minutes to cross the country. The portion of the sun obscured by the moon decreases with distance from the path of annularity.