NOVEMBER STAR MAP |
NOVEMBER 7, 1999: Leonids Reign
- One of the greatest meteor storms of the 20th century could be poised to brighten Lehigh Valley skies during the early morning hours of Thursday, November 18th. This yearís Leonid meteor shower, which runs in cycles of heightened activity every 33 years, has been predicted by some astronomers to produce big dividends in 1999. Comet Tempel-Tuttle passed this way in early 1998. Like a truck dumping dirt on a bumpy road, the comet unloaded ribbons of debris in our part of the solar system, material that the Earth could pass through on Thursday morning the 18th. The signs all point to some region of the world getting a burst of activity resulting in thousands to tens of thousands of shooting stars raining down from the heavens per hour. Presently, Europe and western Africa are the prime target areas, but if Earth intersects the swarm of dirt just a few hours late, the East Coast could be ground zero for some of the best celestial fireworks of this century. Last year, the Leonids also were predicted to produce a flurry of activity. The target area was the Far East. Instead, from California westward across the Pacific, throughout Asia and Europe, large numbers of fireballs were observed, but the main storm never developed. Now a year later, the alignment of Earth and cometary debris seems to be better, and hopes are again running high that on the 18th we could see it raining meteors. Start observing around midnight on the morning of the 18th. If the storm materializes over western Europe and Africa as predicted, weíll see long tailed meteors streaming overhead. If the shower is late by 2-4 hours, the area from which the meteors will be radiating will be higher in the east, and we see the "really big show."
NOVEMBER 14, 1999: Meteor Thursday
- The roulette wheel is spinning in one of astronomyís biggest gambles. Thursday morning could see Lehigh Valley skies bursting with shooting stars, thousands of them, maybe even hundreds of thousands of them, streaking away from the Sickle of Leo, the Lion in the east. Thursday could also be the dawn of disappointment for many weary souls if the clumps of discarded debris from Comet Tempel-Tuttle miss the Earth and leaves us with only the memories of the great Leonid storms of 1966 and 1833. In 1966, I waited impatiently all night for the skies to clear. I was angry and dead tired the next morning when my dad drove me to school. But I knew if I waited long enough, the comet would return; and the Earth at its appointed time would dive through the plane of cometary dust, possibly producing another great spectacle. Meteor Thursday is almost upon us. If a storm doesnít materialize somewhere in the world, then strong displays are conceivable in 2000 and 2001. But after that, the chance of a blizzard of meteors becomes more remote. Jupiterís "strong arm" gravity will change the orbit of the comet ever so slightly, decreasing the chances of a major return of Leonids for several centuries. So we canít just say that in another 33 years, weíll have another opportunity. Itís now or never. The chances of a truly memorable display over Valley skies is probably less than 5 percent. However, in 35 years of observing, I have learned never to say, "Never." Iíll be out Thursday morning looking east after midnight, waiting for that miracle. You should be to. More meteor information at the web site below.
NOVEMBER 19, 1999: Leonids Fizzle for Valley
- The Leonid "meteoric rain" fell mostly in Spain and the Middle East yesterday morning leaving observers in the Lehigh Valley literally out in the dark and freezing from the cold. I know, because I was one of them, bundled in six layers, stuffed into a sleeping bag, with eyes and camera glued skyward. Under spectacularly clear Valley skies, with a frosty wintry Milky Way overhead, rates from the Leonid meteor shower were downright disappointing. My first confirmed Leonid was seen around 11:30 p.m. with the radiant barely above the eastern horizon. High hopes were quickly dashed. It was an hour and 40 minutes later before the next shower-related meteor was seen. But then rates steadily began to build as Leo climbed higher into the sky. This was normal for any night of meteor watching as our observing platform, the Earth, rotated us into the oncoming dust particles. From 1-2 a.m.--6 Leonids, 2-3 a.m.--19 Leonids, 3-4 a.m--16 Leonids, 4-5 a.m.--22 Leonids, and 5-6 a.m.--23 Leonids... Brightening horizons brought a halt to observing at 5:50 a.m. The meteors in general were faint, some at the threshold of visibility. There was not a one spectacular event during seven hours of continuous sky watching; but there were several occasions when a handful of meteors were witnessed within several minutes of each other raising hopes that maybe a stronger display was about to begin. It never happened. It seems that astronomers may have gotten it right and wrong at the same time. Europe and the Middle East got the best views, 1800+ meteors per hour, but the great storm never developed. More about the Leonids next week.
NOVEMBER 21, 1999: Leonids Bright Side
- What happened to the Leonid meteor storm? It never developed. The debris from Comet Tempel-Tuttle, however, did produce high rates for Europe and the Middle East. but little in the way of major significance for the Lehigh Valley. Observers in Spain saw numbers as high as 30 Leonids per minute for a half hour period while Israeli amateurs doubled the rates of western Europe. The observations were centered around 2 hours GMT or 9:00 p.m. EST. For East Coast observers, the burst of activity happened several hours too early, with the radiant, the location where the meteors were coming from, well below our eastern horizon. We were passengers on an Earth located in the lee of the storm. Like a car moving through rain, our position at 9 p.m. was on the back windshield, staying clear of most of the rain (meteors) and completely protected from Leonid meteoroids whizzing past us well outside our atmosphere. Furthermore, meteor rates are mathematically manipulated to show the number of shooting stars which would be visible under ideal conditions. This is called the zenithal hourly rate. It is a way of standardizing observations, but almost always inflates the counts. I calculated the approximate ZHR for my last hour of observations on the morning of November 18. I reported seeing 28 Leonids between 4:50 a.m. and 5:50 a.m. However, due to sky conditions, and the altitude of the radiant, and other standard factors associated with Leonid meteors, my ZHR was just over 200 meteors. Suddenly my rates donít sound that bad. You may have already guessed that the reportedly high European and Israeli rates were also ZHRís manipulated from the raw counts.
- The above photo is comprised of two separate images taken on Thursday morning, November 18, 1999 by Gary A. Becker. The first photo captured four Leonids which occurred in a 30 second burst of activity around 3:30 a.m. EST. To this image was added another Leonid meteor captured just after 4:10 a.m. This meteor appears at the lower right of the photo (5). The pictures were originally imaged on Royal Gold 1000 and manipulated through Paint Shop Pro by the photographer to produce the single high contrast b/w image which is shown here. The Sickle of Leo, shown as a backwards question mark, outlines the head and body of the Lion. The same photo, but without the numbers, appears below.
NOVEMBER 28, 1999: Geminids Perfection
- With the Leonids behind us, there is one more meteor event this year which bears examination. Every December, the Earth intersects a group of meteoroids which are possibly a remnant of the Great Comet of 1680. These shooting stars radiate near the brightest stars of the Gemini Twins, Caster and Pollux, and are known as the Geminids. Unlike the 33 year cyclical burst of activity anticipated by the Leonids, the Geminids put on a very acceptable show each year. The main reason why they are often missed by so many observers is simply due to the cold and clouds of December. First discovered in 1862, hourly Geminid rates have been steadily increasing. In the 1930ís meteor rates of 40-70 per hour could be expected. In the 1950ís 60 meteors per hour was the norm, 80 shooting stars per hour in the 1970ís, and currently 60-110 meteors per hour at maximum. The rate increase is not just wishful thinking. The orbit of these particles is gradually being changed by Jupiter, bringing the main body of meteoroids ever nearer to Earthís path. Rates should reach their maximum sometime near the middle of the next century, but no one is looking for a Geminid storm, just a consistently higher annual rate. What makes this yearís Geminids particularly interesting is that maximum activity occurs between 5-6 a.m. on the morning of December 14. That puts the Eastern US in the best possible location for sweeping up the most meteors. In addition, the moon sets just before 10 p.m. on the 13th, so there will be no degradation of rates due to unwanted moonlight. Look for an on-line Geminid meteor map at the web site below. More about the Geminids next week.