A Shower From a Comet’s Tail

The Leonid meteor showers are peaking this week, so I’ll be out trying to catch a glimpse of them. Unfortunately, Murphy’s Law of Meteors that seems to follow me tends to make meteor shower nights also cloudy nights in Paradelle. Add to that the lack of truly dark skies here and watching for meteors can be difficult.

From midnight to dawn this weekend is a good time to look for meteors in the annual Leonid meteor shower. There is New Moon today and that at least guarantees the darkest skies for the shower’s peak mornings. The peak this year is expected to be before dawn on Tuesday, November 17, but people online have reported sightings already. In an ideal location at the peak, you could see 10 to 15 meteors per hour.

Though meteor showers get their names from their radiant point (the place where they seem to come from) that is not their actual source. The Leonid shower is below the horizon in the constellation Leo the Lion, but the radiant point will rise over the eastern horizon around midnight which is why it will be better to look in the hours before dawn. Actually, you don’t need to know where that point is because they will appear in all parts of the sky.

The actual source is the comet Tempel-Tuttle and the meteor storms occur when the comet is in our neighborhood. 55P/Tempel–Tuttle (commonly known as Comet Tempel–Tuttle) is a periodic comet with an orbital period of 33 years. It was independently discovered by Wilhelm Tempel in 1865, and then by Horace Parnell Tuttle in 1866. The orbit of Tempel–Tuttle intersects that of Earth nearly exactly, so the streams of material ejected from the comet during perihelion (nearest to us) passes do not have to spread out over time to encounter Earth.

Animation of 55P/Tempel–Tuttle orbit around Sun.gif
Animation of 55P/Tempel–Tuttle orbit around Sun – JPL, NASA, CC BY-SA 4.0, Link

 

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Ken Ronkowitz

A lifelong educator on and off the Internet. Random by design and predictably irrational. It's turtles all the way down. Dolce far niente.

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