Watch out for possible meteor outburst by alpha Monocerotids

A little-known meteor shower is set to provide a short-lived outburst on the night of November 21-22, 2019, experts predict.

A bright meteor (not an alpha Monocerotid) flashes through Orion. Image credit: Paul Sutherland

The shower is known as the alpha Monocerotids, and is so-called because the meteors appear to radiate from the direction of the constellation of Monoceros, the Unicorn. (The radiant actually lies just inside neighbouring Canis MInor.)

In most years, rates for this shower are so low that observers are unlikely to notice it above the usual background level of sporadic meteor activity.

But NASA meteor scientist Peter Jenniskens and colleague Esko Lyytinen predict that, for a short time, meteor rates will rise dramatically. The event is likely to last less than an hour, and to occur around 04.50 UT. 

This time particular favours observers in Europe and northwestern Africa because the radiant, to the east of Orion, will be at its highest and skies will be dark. It may also be seen from much of the USA and Canada, earlier in their nights, but no meteors from the shower can be seen before the radiant, near the bright star Procyon, rises late in the evening.

This photo of an alpha Monocerotid was captured from Wilcot, UK, in 2015. Image credit: Richard Fleet

Outbursts of the alpha Monocerotids have previously been observed in 1925, 1935, 1985 and 1995. The first three of these were entirely unexpected, but meteor science and the mapping of meteoroid streams in the Solar System had advanced enough to allow the 1995 event to be forecast accurately.

Now Jenniskens and Lyytinen have found that the Earth’s orbit will intersect with a dense stream of meteoroids in 2019. Previous observations have shown that the meteors were left by a long-period comet, that is a comet travelling in from the depths of the Solar System. The actual comet responsible for the alpha Monocerotids has never been identified.

The International Meteor Organization is keen for amateur astronomers to keep watch on the night of maximum to check whether an outburst occurs, and to count the meteors seen. If rates during the short outburst match the one that occurred in 1995, then an observer with clear, dark skies might expect to see a few meteors a minute.

Meteor expert Peter Jenniskens pictured hunting meteorites in Sudan. Image credit: NASA

The Moon will be a morning crescent in the constellation of Virgo and so not bright enough to spoil the show. But if you can you should watch a part of the sky well away from the Moon so that it does not distract you.

Two other meteor showers, the Leonids and the Taurids, are still also active this week, so you may observe members of those showers too.

We have a full guide to observing meteors visually, plus an article with tips on how to photograph a meteor shower.


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