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The Leonid meteor shower is suppose to be absolutely spectacular tonight.
weekend
Comet's trail expected to ignite big sky show
David Perlman, Chronicle Science Editor Friday, November 16, 2001
--------------------------------------------------------------------------------
Brilliant showers of meteors called the Leonids should streak across the late night sky this weekend, and stargazers are expecting one of the most spectacular displays our solar system can provide.
Beginning late tomorrow night and climaxing around 2 a.m. Sunday, the Earth in its orbit will swing through clouds of tiny fragments left from the tail of a comet that flashes between the sun and Earth roughly every 33 years.
As this debris flares and vaporizes in Earth's high atmosphere, astronomers say the spectacle may even become a full-fledged meteor storm, with hundreds if not thousands of "shooting stars" an hour appearing after midnight tomorrow.
"It's now or never," said Robert Naeye of the Astronomical Society of the Pacific. "Astronomers don't think we'll see another storm like this one until the year 2099. We will probably never see a better meteor shower in our lifetimes."
It depends on the weather, and as of yesterday forecasters were predicting mostly clear skies tomorrow night in San Francisco, the Peninsula and the East Bay, but "mostly cloudy" in Marin and the northern counties.
The Leonid showers should be visible even above city lights, although anyone who ventures into darker country is in for a more fantastic show.
In the Bay Area, amateur astronomers, and professionals, too, will be on hand at seven locations tomorrow night to explain the phenomenon to the public.
The Leonid meteors are so called because they appear to originate from the constellation Leo, although in fact they are infinitely closer to Earth -- flashing less than 100 miles above us. Most years, the Leonids are usually sparse during their annual November visitation.
But this year's display could be the most spectacular since 1966, astronomers say, because Earth will be passing through three distinct trails of debris left from three separate flights of the Tempel-Tuttle comet into the solar system in 1699, 1767 and 1866.
There should be a repeat show next year, but the moon over the Bay Area will be full then, and the sky will be too bright for the meteors to be clearly visible.
"This is the year to see the show," said Peter Jenniskens, a meteor expert at the SETI Institute and NASA's Ames Research Center in Mountain View. "The best way is to make a whole weekend of it. Get out into the country -- up to the mountains if you can -- and be patient. You should make an all-nighter of it."
For folks who can't leave home, urban light pollution will dim the show, although many Leonids should still be strikingly visible. "So be friendly to your neighbors," Jenniskens said, "and keep your porch lights off if you can --
you'll all see better."
Jenniskens is predicting a "classic meteor storm" -- 15 meteors a minute by 1 a.m. Sunday and more than 30 a minute by 2 a.m. Then the numbers will "fade away rapidly," he said. Other scientists have forecast lower counts of six a minute.
As Earth passes through the three trails of debris from Tempel-Tuttle's tail, the meteors -- ranging in size from sand grains to marbles -- will hit the upper edges of the Earth's atmosphere at nearly 160,000 miles an hour, according to Jenniskens.
At roughly 60 miles above the Earth, each meteor will encounter enough of Earth's thin upper atmosphere to heat into incandescence and turn into a tiny cloud of ionized gas as hot as 7,300 degrees Fahrenheit before it vanishes, he said.
Some of the larger meteors may even explode as blazing fireballs in the sky,
as they did during the Leonid shower of 1998, Jenniskens said.
Over the weekend, Jenniskens and colleagues from several research centers will be flying from Edwards Air Force Base aboard a modified Air Force NKC135 tanker aircraft, with 20 observing windows specially built for the scientists.
Originally, NASA invited meteor researchers from five nations to fly with Jenniskens, but because the plane has been on standby since the terrorist attacks of Sept. 11, the foreign scientists will not be aboard, and their instruments will be operated by American researchers.
One major purpose of the flight is to analyze the ionized organic gases that emerge in the dying instants of each meteor.
If those gases survive the intense heat, Jenniskens believes, they may be altered chemically, but still remain in the atmosphere -- a strong indication that similar meteors could well have carried the chemicals essential for life to the surface of the early Earth.
--------------------------------------------------------------------------------
For more details about the Leonid meteor shower, visit the Astronomical Society of the Pacific's Web site at www.astrosociety.org and the NASA site at leonids.arc.nasa.gov.
weekend
Comet's trail expected to ignite big sky show
David Perlman, Chronicle Science Editor Friday, November 16, 2001
--------------------------------------------------------------------------------
Brilliant showers of meteors called the Leonids should streak across the late night sky this weekend, and stargazers are expecting one of the most spectacular displays our solar system can provide.
Beginning late tomorrow night and climaxing around 2 a.m. Sunday, the Earth in its orbit will swing through clouds of tiny fragments left from the tail of a comet that flashes between the sun and Earth roughly every 33 years.
As this debris flares and vaporizes in Earth's high atmosphere, astronomers say the spectacle may even become a full-fledged meteor storm, with hundreds if not thousands of "shooting stars" an hour appearing after midnight tomorrow.
"It's now or never," said Robert Naeye of the Astronomical Society of the Pacific. "Astronomers don't think we'll see another storm like this one until the year 2099. We will probably never see a better meteor shower in our lifetimes."
It depends on the weather, and as of yesterday forecasters were predicting mostly clear skies tomorrow night in San Francisco, the Peninsula and the East Bay, but "mostly cloudy" in Marin and the northern counties.
The Leonid showers should be visible even above city lights, although anyone who ventures into darker country is in for a more fantastic show.
In the Bay Area, amateur astronomers, and professionals, too, will be on hand at seven locations tomorrow night to explain the phenomenon to the public.
The Leonid meteors are so called because they appear to originate from the constellation Leo, although in fact they are infinitely closer to Earth -- flashing less than 100 miles above us. Most years, the Leonids are usually sparse during their annual November visitation.
But this year's display could be the most spectacular since 1966, astronomers say, because Earth will be passing through three distinct trails of debris left from three separate flights of the Tempel-Tuttle comet into the solar system in 1699, 1767 and 1866.
There should be a repeat show next year, but the moon over the Bay Area will be full then, and the sky will be too bright for the meteors to be clearly visible.
"This is the year to see the show," said Peter Jenniskens, a meteor expert at the SETI Institute and NASA's Ames Research Center in Mountain View. "The best way is to make a whole weekend of it. Get out into the country -- up to the mountains if you can -- and be patient. You should make an all-nighter of it."
For folks who can't leave home, urban light pollution will dim the show, although many Leonids should still be strikingly visible. "So be friendly to your neighbors," Jenniskens said, "and keep your porch lights off if you can --
you'll all see better."
Jenniskens is predicting a "classic meteor storm" -- 15 meteors a minute by 1 a.m. Sunday and more than 30 a minute by 2 a.m. Then the numbers will "fade away rapidly," he said. Other scientists have forecast lower counts of six a minute.
As Earth passes through the three trails of debris from Tempel-Tuttle's tail, the meteors -- ranging in size from sand grains to marbles -- will hit the upper edges of the Earth's atmosphere at nearly 160,000 miles an hour, according to Jenniskens.
At roughly 60 miles above the Earth, each meteor will encounter enough of Earth's thin upper atmosphere to heat into incandescence and turn into a tiny cloud of ionized gas as hot as 7,300 degrees Fahrenheit before it vanishes, he said.
Some of the larger meteors may even explode as blazing fireballs in the sky,
as they did during the Leonid shower of 1998, Jenniskens said.
Over the weekend, Jenniskens and colleagues from several research centers will be flying from Edwards Air Force Base aboard a modified Air Force NKC135 tanker aircraft, with 20 observing windows specially built for the scientists.
Originally, NASA invited meteor researchers from five nations to fly with Jenniskens, but because the plane has been on standby since the terrorist attacks of Sept. 11, the foreign scientists will not be aboard, and their instruments will be operated by American researchers.
One major purpose of the flight is to analyze the ionized organic gases that emerge in the dying instants of each meteor.
If those gases survive the intense heat, Jenniskens believes, they may be altered chemically, but still remain in the atmosphere -- a strong indication that similar meteors could well have carried the chemicals essential for life to the surface of the early Earth.
--------------------------------------------------------------------------------
For more details about the Leonid meteor shower, visit the Astronomical Society of the Pacific's Web site at www.astrosociety.org and the NASA site at leonids.arc.nasa.gov.
