Friday, October 28, 2005

Chronicle Photographer Lance Iversen Captures Images of UFOs

UFOs Over San Francisco Cropped
Spellbound by sky lights
Bright twinklers were nearby Mars and Venus, say astronomers -- or were they?

By David Perlman
Chronicle Science Editor

     Mysterious, bright lights in the night sky Wednesday that alarmed or bemused scores of Bay Area residents were not mysterious at all but most likely a pair of planets whose orbits around the sun are carrying them close to Earth right now.

     Others are not so sure.

     Andrew Fraknoi, chairman of the astronomy department at Foothill College, said the lights were probably Mars and Venus, two planets that currently appear close together and will probably remain brilliant for another week or two until their orbits begin moving them away from Earth again.

     If they seem to take on unusual colors, twinkle or even move, Fraknoi said, it's because of an optical illusion caused by Earth's somewhat dense, moisture-laden lower atmosphere. Clouds scudding by also may obscure them briefly before they reappear, he said.

     Residents across California and people as far east as Las Vegas reported seeing the lights in the sky late Wednesday. Those who called space officials at Vandenberg Air Force Base on the Central Coast and the Federal Aviation Administration drew the usual response Thursday: No, there were no missile launches, no wandering airplane pilots had failed to file flight plans, no military jets were aloft, and no one was suggesting UFOs.

     No one except astronomers could offer an explanation.

     Chronicle photographer Lance Iversen caught images of the peculiar lights in his camera around midnight Wednesday, looking east from Twin Peaks. Mars and Venus would have been visible in the eastern skies at that time.

     Iversen said that at one point he saw four distinctly separate lights, but then saw only two that seemed to move in unison.

     "They were just lights moving in the sky," he said. "They might have been helicopters, although I couldn't see any fuselages, but the lights were moving far enough and fast enough so they couldn't have been planets -- and I know planets when I see them."

     But Fraknoi said Venus and Mars remain the best explanation for the lights.

     In their orbits around the sun, all planets move at different speeds, just as the Earth does, and periodically their varied speeds cause them to catch up and overtake the Earth's orbital flight and bring them closer to our home planet.

     In fact, the Red Planet will be exactly 43.1 million miles from Earth at 8:25 p.m. Saturday, and its orbit won't bring it that close to Earth again until the summer of 2018, according to astronomical calculations.

     Venus, which orbits the sun inside Earth's orbital path, is now about 106 million miles away -- no record, but close enough to appear much brighter than usual.

     According to Fraknoi, Mars now far outshines even the brightest of all the stars in the sky, and when skies are clear, the fourth planet from the sun could look even bigger than normal. Its brilliance should be apparent above the eastern horizon soon after sunset, but will appear even brighter as it climbs higher in the sky during the night.

     On the night of Nov. 7, Mars will be directly opposite the sun in relation to Earth -- a position astronomers call opposition, which means it will rise above the eastern horizon just at sunset, climb higher and higher, and remain in the sky all night until it sets at sunrise.

     The Martian orbit last caught up with Earth's in August 2003, and on that occasion it was even closer -- about 36 million miles away. It won't come any closer than that for another 60,000 years, NASA astronomers have calculated.

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