The usually sparse annual Alpha Monocerotid meteor shower may be a sensational though probably short-lived spectacle in the night of November 21-22 (Thursday-Friday).
See the end note about enlarging illustrations.
Our diagram shows the scene as the source of the meteors has climbed for a couple of hourse into the sky, but you might start looking earlier, since, as we’ll see, the peak of the outburst could be just before midnight for North America’s Eastern time Zone, just before 11 p.m. for the Central and 9 p.m. for the Pacific zones.
For alerting me to this, I’m indebted to my friend and meteor expert Alastair McBeath, and I’m going to quote some of his words.
The prediction is “based on a re-evaluation of the shower’s past activity, and a different assumption regarding the parent comet’s behaviour. This has suggested there could be a fresh, probably short-lived, outburst with ZHRs of order 400 or more, centred at 04:50 UT on 2019 November 22 (so overnight on Nov 21-22 for Europe, including the UK). As ever with meteor showers, there are of course no guarantees, but if the strength estimate is right, that would make it comparable to the 1995 event.”
Some explanations:
The radiant of a meteor shower is the point or small area from which the meteors see, to radiate. The streaks in our diagram are merely suggestive; they can appear far off from the radiant. Radiant positions shift from day to day as Earth moves along its orbit through the meteor stream; hence the arrow through the radiant in the diagram. And The Alpha Monocerotid radiant has shifted over the decades and is now nearer to brilliant Procyon, the alpha star of Canis Minor the Lesser Dog, than to the alpha star of the constellation Monoceros the Unicorn. The Alpha Monocerotids happen to travel almost exactly in Earth’s equatorial plane.
“ZHR” is zenithal hourly rate, the number of “shooting stars” one alert person might count in an hour at the peak time and in perfect sky conditions with the radiant overhead. Actual rates are generally much less.
This shower’s usual ZHR may be only about 3. But there were outbursts that were complete surprises in 1925, 1935, and 1985, and a predicted and well-observed one in 1995. If the ZHR indeed reaches 400 this time, it will be a feast.
The parent comet is, I believe, long-period-comet C/1943 W1 Van Gent-Peltier-Daimaca, which made its only known dive through the inner solar system in 1944.
The International Meteor Organization has a lot about the reasons for thinking there may be an outburst.
To turn to matters more vital for our planet, here is a scary graph from today’s news.
These are the rates of production of fossils fuels (oil, gas, coal), up to the present and projected.
Black: the rate that almost all nations pledged to stick to, by the Paris Agreement of 2015 (from which the U.S. has withdrawn).
Blue: the rate to avoid world temperature rise of 2 degrees Celsius above pre-industrial levels, once considered the tipping point to runaway heating.
Yellow: the rate to keep the rise below 1.5C, now understood to be the more likely tipping point.
Red: the actual current plans of the nations, according to this latest and largest report.
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ILLUSTRATIONS in these posts are made with precision but have to be inserted in another format. You may be able to enlarge them on your monitor. One way: right-click, and choose “View image”, then enlarge. Or choose “Copy image”, then put it on your desktop, then open it. On an iPad or phone, use the finger gesture that enlarges (spreading with two fingers, or tapping and dragging with three fingers). Other methods have been suggested, such as dragging the image to the desktop and opening it in other ways.
This weblog maintains its right to be about astronomy or anything under the sun.
It’s clear now there was indeed an outburst event from the Alpha Monocerotids (AMO) on November 22 this year, about when expected, although activity was probably some way below that observed in 1995. Current estimates, subject to change as the detailed analyses progress, suggest the event peaked at about 04:57 UT, give-or-take five minutes. Estimated Zenithal Hourly Rates – EZHRs – for the highest level of activity (which probably lasted just a few minutes, so this is not the same as a “true” ZHR) were probably of the order of 40-100, an uncomfortably large range of values because it’s unclear presently how great a proportion of fainter-than-normal AMO meteors were present during the outburst. The whole event was short-lived, with above normal ZHRs reported between roughly 04:46 and 05:26 UT. The “Live” International Meteor Organization graph, using five-minute data bins for the detected visual meteor counts, has indicated there may have been a secondary peak, with EZHRs of maybe 70 or so at about 05:08 UT. A full examination of all available data is currently underway, and hopefully these early estimates can be better refined subsequently.
For myself in the UK, there was sadly no repeat of the near-perfectly-timed sky clearance I enjoyed for the 1995 AMO outburst, with only solid overcast and yet more cold rain all night on Nov 21-22. Even back then, so far as I’m aware, I was one of just two UK observers to see anything of the 1995 event, thanks to yet more typically poor November weather. I described that outburst at the time as like having the Perseids turned on for half-an-hour on an early winter’s night! Not quite so good this time it seems, but I’m still sorry to have missed what there was.
There’s a good chart showing who has a good chance to see this shower burst, world-wide at that time, at the Sky and Telescope web site. That’s geometrically speaking, of course. Weather is another factor.