Oct 17, 2000

Weekend Meteors

On Friday the 13th of October a brilliant fireball startled stargazers in Texas, Oklahoma, and Kansas. But that was just a piece of space junk -- a real meteor shower arrives this weekend.

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October 18, 2000 -- Last Friday, the 13th of October, thousands of high-school football spectators were gathered in outdoor stadiums across the Midwestern US when something happened to distract even diehard fans from action on the field below.

With no warning, a fiery meteor as bright as the full Moon streaked over Texas, Oklahoma, and Kansas around 7:30 p.m. local time. It was a halftime show from the heavens!

"At first I thought it was a high-flying aircraft with its landings light on," recounts Alex Leslie, who saw the meteor from a Hill City, Kansas, football game. "As it passed almost directly south of us, it separated into about five burning points, mainly white but some green hues, too. A 'smoke trail' lingered for some time after the object passed. It took about five minutes to cross the entire sky." [Alex Leslie's full account]

Emergency phone lines were jammed with UFO reports soon after the sighting, but in this case the strange lights were not from outer space. The object that slowly burned across Texas skies had left Earth only hours before.

Above: On Friday the 13th of October, startled onlookers in Kansas saw this disintegrating fireball high overhead. Photo courtesy KSN News. [more information]


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Earlier on Friday a trio of Glonass satellites lifted off from the Baikonur Cosmodrome in Kazakstan aboard a single Russian Proton rocket. Glonass is the Russian equivalent of the American Global Positioning System. The successful launch added three new satellites to the Glonass array and, unintentionally, triggered the Friday night sky show over Texas.

"In my opinion, the [Texas fireball] was the re-entry of the Proton rocket's 4th-stage casing," says Alan Pickup, a satellite decay expert who works at the United Kingdom's Astronomy Technology Centre at the Royal Observatory in Edinburgh. "It was a cylinder 3.7m in diameter and 4m long that weighs some 800 kg."

"The object had passed through perigee (closest approach to Earth) at 7:19 p.m. Central Daylight Time (00:19 UT) when it was over the eastern Pacific en route to the Mexico coast. It would have passed 3.1 degrees west of Abilene, Texas, at 7:25 p.m. (00:25 UT) and almost directly over Lubbock, Texas, 19 seconds later. Its track continued over Oklahoma and Kansas towards Lincoln, Nebraska, which it would have reached at about 7:27 p.m. local time were it still in orbit."

Case closed--the fireball came from Asia, not from outer space.

But there is a real meteor shower in store this weekend for erstwhile star gazers inspired by Friday's fiery display.

Earlier this month our Earth's orbit carried our planet into a diffuse stream of dusty debris from Halley's comet. Until now we've been in the rarefied outskirts of the debris field, but we're heading for denser parts. Tiny bits of Halley dust that burn up in our planet's atmosphere will produce a meteor shower, called the Orionids, that peaks this weekend, October 21st and 22nd. Orionid meteors won't be nearly as bright as a decaying Proton rocket shell, but the display should be nonetheless pleasing.

the orbit of Halley's comet
Earth passes close to the orbit of Halley's comet twice a year, once in May and again in October. Although the comet itself is very far away -- presently beyond the orbit of Jupiter -- tiny pieces of Halley are still moving through the inner solar system. These particles are leftovers from Halley's close encounters with the Sun every 76 years; each time the comet returns, solar heating evaporates about 6 meters of ice and rock from the nucleus. The debris particles, usually no bigger than grains of sand, gradually spread along the comet's orbit until it is almost uniformly filled with tiny meteoroids. When these meteoroids strike Earth's atmosphere they produce the Orionid meteors in October and the eta Aquarid meteors in May.

No matter where you live, the best time to see Orionid meteors will be during the hours before dawn on October 20th through 23rd. Rural observers should enjoy as many as 20 shooting stars per hour. During this year's broad peak, centered approximately on Oct. 21st, the light of the waning quarter Moon will make faint meteors hard to spot; pre-dawn observers on the 22nd and 23rd may have better luck with diminishing moonlight.

Orionid meteoroids are fast. They hit the atmosphere at a head-spinning velocity of 90,000 mph. There's no danger, though, because the tiny specks of dust disintegrate well above the stratosphere. True to their name, the Orionids will appear to stream from the constellation Orion, which is high in the southern sky before dawn. The best place to look for meteors is not, however, directly toward Orion. Orionids can appear anywhere in the sky, with tails that point back to the shower's radiant above Orion's left shoulder. Experienced meteor watchers suggest looking 90 degrees away from the constellation -- that's usually the best direction to watch Orionids fly by. Also, try to choose a dark area of the sky away from the bright Moon.

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Above: The sky as seen by an observer looking south from mid-northern latitudes at 3 a.m. on October 21, 2000. The Orionids radiant, denoted by a red dot, is about 50 degrees above the southeastern horizon. Because Orion is near the celestial equator, the Orionids are a good shower for both northern and southern hemisphere observers. A similar sky map for southern meteor watchers would show the Orionid radiant 40 degrees above the north-northeastern horizon at 3 a.m. local time.

Even if the usually-reliable Orionids fail to produce a pleasing show, there's still plenty to see. October's glittering pre-dawn sky includes Jupiter, Saturn, and the brightest star of all, Sirius -- all near to the Orionids radiant. Waking up early for this weekend's meteors is a no-lose proposition!

You can follow Orionids activity, with updates and images, at

Web Links

Alan Pickup's Satellite Evolution and Decay Web Site -- find out which piece of space junk will decay next!

Oklahoma-Texas re-entry -- details from Alan Pickup

Halley's Comet Returns in Bits and Pieces -- 1998 Science@NASA story about the Orionid meteor shower.

Witnesses See Fire in the Sky -- a weekend report from KSN News and MSNBC -- news about comets, meteors and asteroids; features a suggested ground track for the Texas fireball.

Glonass Home Page

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