THE SOUTHWORTH PLANETARIUM

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70 Falmouth Street   Portland, Maine 04103

43.6667° N                   70.2667° W 

Altitude:  10 feet below sea level

Founded January 1970
Julian Date: 2458808.16

2019-2020:  LVI

            "We can't wait for yesterday."

THE DAILY ASTRONOMER

Wednesday, November 20, 2019

Micro Meteor Outburst?

or

Alpha What?

The Alpha Monocerotids. 

Never heard of these?

Be consoled.   It's a minor meteor shower that is not only centered around an obscure constellation, but peaks around the same time as the much more famous and furious Leonids.     Most years the Alpha Monocerotid "peaks" are pathetic, and often don't even occur at all.  This year, however, this usually underwhelming shower could very well produce a spectacular, though fleeting, meteor storm.   If it does occur, it will last less than an hour and the activity one observes will depend on the location.

The Alpha Monocerotid "burst."  We could possibly experience a rapid meteor storm produced by the usually unremarkable Alpha Monocerotid shower.    The peak time will be around 11:50 p.m. on November 21st.     Observers should look toward the eastern sky just beyond Orion's belt to see, perhaps, a stunning meteor outburst.       Image: Sky and Telscope

The Alpha Moncertoids appear to emanate from a region around Alpha Monocerotis, the "brightest" star in the modern constellation Monoceros, the Unicorn.  This star, which lacks a proper name owing to its faintness, is six times dimmer than Polaris.   It was assigned the alpha designation in the Bayer system only because the constellation's other component stars are even fainter.   Developed in the 17th century by Dutch cartographer Petrus Plancius (1552-1662),  the faint Monoceros occupies the dark region within the Winter Triangle, formed by Betelgeuse (Orion), Sirius (Canis Major) and Procyon (Canis Minor).     Monoceros is so faint one would be hard pressed to even notice it in completely dark skies.

The meteor shower named for the constellation's bright star is also obscure mainly because the cometary dust tail from which the meteoroids originate is thin and weaves around the area through which Earth revolves.      Meteor showers occur when Earth moves through a field of particles a comet -or, rarely, an asteroid-releases when moving through the inner solar system.  We experience a meteor shower's peak when our planet passes through the densest part of that stream.       Quite often, Earth will actually miss the stream that the Alpha Monocerotid's unknown parent comet left in its wake.    However, astronomers have noticed outbursts in both 1985 and 1995.     Two astronomers, Esko Lyytinen of the Finnish Fireball Network and Peter Jenniskens of NASA's Ames Research Center, have paid close attention to this shower for many years.   They noted that Earth's position and other circumstances during this year's Alpha Monocerotid peak time are very similar to those in 1995, the year of the last dramatic outburst.  Hence, their prediction of another rapid meteor storm.

WHERE AND WHEN?

The peak should last no more than 40 minutes.    The best time to watch will be around 11:50 p.m. EST. on November 21st.   Fortunately, being on the US East Coast, we'll be well placed to see these meteors. Also, the waning crescent moon won't rise until 12:03 a.m., so we won't have to contend with any lunar light interference.    Unfortunately, the radiant will be low in our sky:  at that time, Monoceros will be ascending in the eastern sky.      More meteors are visible when the radiant is at or near the zenith, the point directly overhead.  Consequently, observers in parts of South America will be in the best position to observe this rapid peak.

We don't know what we'll see: perhaps dozens of meteors a minute!    The 1995 peak was 400 an hour, which is a bit misleading as the peak lasted less than an hour and the 400 number was an extrapolation.   Meteor shower rates are notoriously difficult to predict as we don't have direct observations of the comet stream that produces them.  However. if you're out on November 21st just before midnight, be sure to look over into the east, in the dark region abutting Orion's belt.   There, if only for a few minutes, one might behold a meteor spectacle greater than anything the Leonids could possibly produce this year.....maybe.      

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