As posted on AZDailySun.com on May 21, 2022
On the evening of May 30, the sky may come alive with an outburst of meteor activity. The result of a comet that broke apart a quarter century ago, the so-called Tau-Herculid Meteor Shower could exhibit thousands of shooting stars in a short period of time.
Such events are hard to predict, and it’s possible that the whole affair will be a dud, with minimal meteor activity. Despite this uncertainty, it will be worth hedging bets and checking out the sky on the 30th because witnessing such a celestial display can be downright exhilarating.
Astronomers predict that if this event does play out, it will be sometime on the 30th between 8:11-10:45 p.m., with peak activity between 9:45-10:45 p.m.
“Some calculations are suggesting that this event could produce thousands of meteors per hour and thus become what is known as a meteor storm,” said Nick Moskovitz, a planetary astronomer at Lowell Observatory. “My sense is that there is roughly a 50/50 change of that happening.”
The story of this potential meteor storm begins in 1930, when German astronomers Arnold Schwassmann and Arno Wachmann discovered a comet. Named Comet 73P/Schwassmann-Wachmann after its discoverers, it drew little attention and in fact was soon mostly forgotten; despite the fact that it orbited the sun in the relatively short time of 5.4 years, astronomers didn’t see it again until the late 1970s. This lack of observation was partly due to the faintness of the comet, and partly because the gravity of the king of the planets, Jupiter, yanked it around and changed its orbit. This meant that, like the bad guys in Raiders of the Lost Ark, astronomers were “digging” in the wrong place.
Since relocating the comet — in its new orbit — in 1979, scientists have consistently observed it during its regular passes through the solar system. During one of these passes, in 1995, the comet appeared hundreds of times brighter than in the past. The reason soon became apparent: the comet had broken apart, with fragments spreading throughout its orbital path.
What does this have to do with meteor showers and storms? At any given time, a piece of space debris may come in contact with Earth’s atmosphere and burn up as a meteor. Likewise, if a collection of cometary fragments — like those of 73P/Schwassmann-Wachmann — comes in contact with Earth, they will burn up. Only in this case, multiples fragments means multiple meteors. Such events are called meteor showers, and some of the best-known ones may exhibit dozens of meteors per hour as seen from Earth.
Meteor showers are typically named after the area of sky from which the meteors appear to originate (called the radiant). Astronomers thus named the one associated with Comet 73P/Schwassmann-Wachmann the Tau Herculid Meteor Shower, after a star in the constellation Hercules.
Historically, the Tau Herculid Meteor Shower has produced relatively few meteors. However, Comet 73P/Schwassmann-Wachmann has continued to break apart, and scientists believe that this fresh swarm of debris may collide with Earth’s atmosphere, and at just the right speed, to produce an event during which thousands of meteors may be visible, if but faintly; thus, a meteor storm.
As an aside, when the orbit of Comet 73P/Schwassmann-Wachmann changed, the radiant of its associated meteor shower also changed, to the constellation Bootes. The shower is nevertheless still called the Tau Herculid Meteor Shower, a misnomer of sorts. Whatever it is called, the possibility of this shower becoming a storm on the 30th is strong enough to warrant spending some time outside and gazing at the sky.