March 21, 2019

AstroEvent: the Leonid Meteor Shower.

This week, be on the lookout for the meteor shower that can roar like a lion, but this year will probably meow like a kitten. The infamous Leonid meteors peak on the morning of Wednesday, November 17th. This shower has been known to produce storm intensity outbursts with a zenithal hourly rate (ZHR) in access of +1,000 roughly every 33 years, which last happened in 1999 & 2000. Last year, the Leonids had a minor brief peak over +60. This year is forecast to be nothing special, with rates probably topping 20 per hour. Still, the Leonids are always one shower to keep an eye on, as we definitely don’t know all of the intricacies of its ancient meteor streams… that big, dense, undiscovered knot could be lurking, just waiting to intersect our orbit.  This year, the Moon will be at 84% phase waxing gibbous and will set around 3AM local, providing a brief window of early morning darkness right before dawn. The Leonids will be active in the early AM hours all week.  Find as dark a site as possible, and don’t forget to count and report how many meteors you see from your location. The Leonids are swift movers emanating from the asterism of the sickle in the constellation Leo, and the parent comet is Temple-Tuttle. Good luck, and stay warm!

This week’s astro word is Airglow. This is yet another insidious factor that stands been you, the backyard observer and pristine optimal skies. Airglow is a pervasive background luminosity that is caused by charged oxygen and nitrogen atoms giving off a delayed luminescence from energizing caused by the Sun and cosmic rays. This is yet another reason that world class telescopes are located on windswept mountain tops or in space; airglow at sea level can noticeably knock down your local limiting magnitude a notch or two. In fact, airglow intensity & luminosity can change noticeably and measurably during the course of the 11 year solar cycle! This is but one factor that will lead to a significantly lower ZHR than is published this or any meteor season.




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