Image by S. Molau and P. Jenniskens, NASA Ames Research Center
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Stars seem to fall like rain during the 1995 Alpha Monocerotid meteor outburst.

Image by S. Molau and P. Jenniskens, NASA Ames Research Center

How to see this week's intense 'unicorn' meteor storm

Astronomers expect that this year’s Alpha Monocerotid meteor shower will be an epic outburst with possible rates of up to 400 shooting stars an hour.

Sky-watchers may get to see 2019 really go out with a bang, with the expected arrival this week of an explosion of shooting stars.

If astronomers’ predictions hold true, the Alpha Monocerotid meteor shower could come to life in dramatic fashion on November 21 and 22, with possible rates of up to 400 shooting stars an hour during its relatively brief peak. Such an outburst would make this shower at least four times more intense than the peak meteor rates seen during the more famous Perseid and Geminid annual meteor showers.

The Alpha Monocerotidsare so named because the meteors seem to radiate from the constellation Monoceros, the unicorn. Like other annual meteor showers, the Alpha Monocerotidshappen when Earth plows through a trail of debris left in the wake of a sun-orbiting comet. The small grains of rock and dust burn up as they careen through our atmosphere, creating dazzling streaks of light. (Find out how scientists in Japan hope to create artificial meteor showers on demand.)

However, unlike more prolific showers that regularly deliver dozens of meteors an hour, the Alpha Monocerotids are usually fairly quiet. Their claim to fame instead comes from intermittent bursts of activity that, at times, produce astonishingly high counts of hundreds or even more than a thousand meteors an hour.

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“Most years, our planet misses or grazes the meteor stream, but rarely, we actually plow through a denser part of the debris, and this can cause noticeably much more dramatic meteor activity in our skies,” says meteor expert Peter Jenniskens, a senior research scientist at the NASA Ames Research Center.

Big meteor outbursts from this shower were recorded in 1925, 1935, 1985, and 1995. The first three of these occurrences caught sky-watchers by complete surprise. But Jenniskens helped predict the 1995 shower and was then able to witness it first-hand from the Spanish countryside.

“It is amazing to be part of only a handful of people to have ever seen this shower, which had previously been reported as ‘stars falling like rain’,” Jenniskens says. “I came in with low expectations at the time, trying to confirm my predictions, but it became immediately obvious when the meteors started to race across the overhead sky at amazing rates of up to five meteors a minute that we were indeed moving through a dense part of the debris stream.”

This year, Jenniskens and fellow meteor forecaster Esko Lyytinen from the Finnish Fireball Networkused existing data from previous storms to create computer models of Earth moving in relation to the positions of past meteor clouds. Their predictions suggest that Earth will slam into the same stream that it encountered nearly a quarter-century ago, which means 2019 should deliver a similarly spectacular sky show.

When and where is the best time to look up?

This time of year,the constellation Monoceros rises above the northeast horizon in late evening across the Northern Hemisphere. That means observers should face the eastern sky to see the most meteors. The best views will be from dark sites away from city lights across eastern North America, South America, western Europe and northwest Africa.

Annual meteor showers typically have peak activity that can last for hours, with straggler meteors visible for days or weeks before and after the event. In this case, however, the debris stream that causes the shower is very narrow—less than 32,000 miles wide—so the peak is expected to last from a mere 15 minutes to an hour. (Find out why the moon releases surprising amounts of water during meteor showers.)

Jenniskens and Lyytinen predict that the peak of the outburst will arrive at 11:50p.m. ET on November 21 (4:50 UT on November 22). But because that peak time is somewhat uncertain, Jenniskens suggests that observers get a head start and begin looking up an hour or two beforehand.

If you’re not in the right location to watch the outburst in person, the Virtual Telescope Project will broadcast a livestream that will start at 11:15 p.m. ET (4:15 UT).

What can meteor watchers expect to see if this outburst occurs?

If the predictions bear out, sky-watchers should expect to see few to no meteors before the outburst begins.

“We are not sure how strong the display will be exactly, since we are not sure how deep Earth will be moving through the meteor stream,” he adds. “But most meteors will be easy to see, since they will be as bright as well known naked-eye stars like Polaris, Deneb, and Vega.”

Once it starts, Jenniskens recommends that people keep watching for about an hour to ensure they see the full show.

“Expect to see a sudden appearance of meteors, and an equally dramatic hard stop,” he says.

Clear skies!

Andrew Fazekas, the Night Sky Guy, is the author of Star Trek: The Official Guide to Our Universe and the 2nd edition of The Backyard Guide to the Night Sky. Follow him on Twitter, Facebook, Instagram, and his website.