Quadrantids open the year

In the night between January 3 and 4 come the Quadrantid meteors.

See the end note about enlarging illustrations.

I was pleased with this arrangement I hit on in Astronomical Calendar 2023 for showing most of what is to be shown about each major meteor shower. A group of four illustrations:

– Space view of how the meteor stream intersects Earth’s orbit, causing the annual shower.

– Under that, a closer space view of Earth, showing how it spins as it advances, and the directions from which it is met by sunlight, moonlight, and the meteors.

– To the right, a sky scene showing how you will see the radiant of the shower appear above the horizon.

– Above that, a closer-up chart of the part of the starry sky where the radiant is.

The radiant is the place among the stars from which the meteors fly out to any part of the sky. Usually the constellation in which the radiant happens to be gives the shower its name: Leo, the Leonids, etc.

One of the tricks played by goblins on those who offer to explain things astronomical is that the dear Quadrantids are the first shower of the year. We have to start off by admitting that there is no constellation Quadrans.

Once there was: Quadrans Muralis, the “wall quadrant,” an instrument for measuring the altitudes of stars. It was one of the “modern” constellations, added after the Renaissance to the 50 handed down from ancient Greek astronomy. It was drawn on a chart by Jérome Lalande in 1795, got the Latin version of its name in 1801. It filled an area north of Boötes; did not inspire fondness, and was ignored when the constellations were officially delineated in 1929. The area remains with Boötes.

And yet, the Quadrantid name works better than “Boötid” would. Being off the north end of the constellation figure, it is far from the stars that familiarly mark that figure, especially Arcturus. And there is a (usually) lesser shower called the June Boötids.

Northern Boötes is quite far north, near the end of the Big Dipper, so that for north-hemisphere people the Quadrantid radiant is in the sky almost all of the long winter night. And the zenithal hourly rate (ZHR, the number one observer might expect in good sky conditions around the shower’s peak time with the radiant overhead – actual counts are likely to be lower) is given as 110, one of the best.

Here is the sky scene as the Quadrantid radiant comes into view, for a mid-USA location.

As the radiant climbs slantingly up from the northeastern horizon, more meteors from it are likely to be in the sky.

But then there’s moonlight. This year, the Moon, not long before its full phase, is high in the sky, over in Taurus. And this includes the time when the shower is expected to be at its peak, around 4 Universal Time (4 AM in Britain, 11 PM in North America’s Eastern time zone). Though half a sky away from the radiant, it will make the fainter meteors in its region harder to see. It will not go down and set till around 5 AM. By then the radiant will be highest, about overhead. So between 5 AM and morning twilight may be the time to look.

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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” or “Open image in new tab”, 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.