What Planet is This?

13 Aug 2005

August Meteors

The Perseids are a meteor shower caused by the Swift-Tuttle comet that provide a display every 12th August. They're called the Perseids because they appear to radiate from the constellation Perseus, which was one of Ptolemy's original 48 constellations and is still one of the IAU's 88 contemporary ones. This year, the peak ZHR for the Perseids occured at about 05:00 UTC, so even though the sun was due to rise a bit before that time, I was parked at a window looking into the sky.

It is possible to see meteors during the day, but they're exceedingly rare. Only the very brightest type, called fireballs, can be seen, and they have to be of magnitude -6 or brighter. The AMS estimate that you'll only see one of these once in every 200 hours of observing time. Nonetheless, in the exact same minute that the sun rose (according to Heavens Above, a great site), I saw a bright orange glow in the SSW, at an altitude of about 35°, whose origin I later traced as being the constellation of Perseus. But I don't think it was a fireball.

The duration of the event was about fifteen seconds. The glow had a constant steady motion, in an uninterrupted straight line. The sky was gradually clouding over at the time, and may have obscured the last second or two of the object's visibility, but I'm pretty sure that it wasn't visible before or after the time I viewed it. The main features that make me think it wasn't a fireball were its slow constant movement, and its constant luminousity. It's very rare for meteors of any kind to last that long, too. It displayed no tail, and I'm pretty sure that it was actually an aeroplane reflecting the dawning sun.

The Perseids are a pretty major storm, but from time to time the November Leonids far outshine them. They can fall with such rapidity that it appears to be raining stars, but such events occur with a fair amount of unpredictability. It mainly depends on the path that the Earth takes through the tail of the comet Tempel-Tuttle, which orbits the Sun every 33 years. One site is predicting that at 01:40 UTC on the 21st November, the Earth will be passing through a trail put down by the comet in 1167. The maximum ZHR from this trail will be 16, which is far from the Leonids' peak.

It was 101 years since the Norman Conquest when Tempel-Tuttle spewed out what are likely soon to become meteors, and apart from the fact that Sir William Marshal, the "greatest knight that ever lived" was knighted in that year, it was a slightly boring year historically. Marshal later went on to observe the signing of Magna Carta in 1215. The definite article is not used in academic style, before "Magna Carta" because there's no definite article in Latin, though that seems uncannily like the split infinitive argument.

Halley's Comet, which I pronounce to rhyme with bailey, was at perihelion seven years after the signing of [the] Magna Carta, its second return after the Norman Conquest. One of the people who commented on it in 1066, and who had possibly seen it the time before too, was Eilmer of Malmesbury, a Benedictine monk who once launched himself with wings off of the top of Malmesbury Abbey, and flew for a furlong before landing and breaking his legs. He was going to attempt to fly again, this time with a tail, but he was forbidden by the abbot of the Abbey.

Cite: Palmer, S.B. (2005). "August Meteors", in: What Planet is This?
Archival URI: http://inamidst.com/notes/augustmeteors


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I omit the article before "Magna Carta" because it's a name. Some names, true, do take definite articles, like the Internet, but the Ukraine and the Argentine have become Ukraine and Argentina. The [Annexed District of] the Bronx [River], however, remains triumphantly the Bronx.

John Cowan, Sun Aug 14 01:12:23 2005


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