Darn moon. We love its radiance but sometimes it just gets in the way. Count on it being there Monday morning Oct. 21 during the peak of the annual Orionid meteor shower. The shower is best seen in the wee hours before dawn when the radiant point, the spot in the sky from which the meteors will all appear to radiate, is high in the south above the upraised arm of Orion the Hunter.
Normally we’d expect to see up to 20 very swift meteors per hour but moonlight will halve that number. Don’t let that stop you. The sun rises late, so you can squeeze in a little meteor watching between 5 and 6 before work.
Use the morning to dig out that old telescope and check in on Jupiter and the wonderful display of lunar craters along the moon’s terminator, the dividing line between day and night. I usually multi-task during meteor showers, poking the scope around from this to that while taking breaks for meteor-watching.
The Orionids are so-named because all the meteors appear to originate from northern Orion. But they’re also “Halleyids”, crumbs dropped by Halley’s Comet during its 76-year orbit of the sun.
Each streak of light you see signals the incineration of a flake of Halley’s Comet, the parent comet of the Orionids. Every year in late October, Earth cuts across Halley’s orbit and bits of dust shed by the comet from previous passes near the sun burn up as they strike the upper atmosphere at speeds of 148,000 mph.
Few showers offer up faster meteors. Don’t bother pointing one out to an observing companion – it’ll be gone as soon as you open your mouth. Most tear across the sky in second or less.
We cross Halley’s orbital path twice a year, and each time we do, our planet slams into sand-sized bits of debris strewn by the comet during the many times it’s circled the sun. Our other encounter with Halley leftovers happens every around April 21 during the Delta Aquarid shower.
Watch for Orionids between about 2 a.m. and dawn. South or southeast is a good direction to face once you’re cozy under a big blanket to stay warm. The shower lasts a few days, so if the weather looks bad, try the mornings before and after Monday’s peak.