On the last morning of May, there is a chance of a meteor shower.

We may see nothing at all if predictions hold true, as there is a chance of a rare meteor shower on May 31st. There is a wonderful world of meteor shower predictions.

The story begins with the discovery of the periodic comet 73P/Schwassmann-Wachmann 3 in 1930. We will refer to it as simply "Comet 73P" from here on out. Astronomers Arthur Wachmann and Carl Schwassmann caught a comet moving through the constellation Hercules.

It was the comet's elliptical path that gave observers pause, as it gave the comet a good chance of being a splendid object.

The orbit of Comet 73P. Credit: NASA/JPL

But such was not to be, as comet 73P was a decided under-performer during the 1930 apparition, only topping out at +7th magnitude and never really breaking naked eye visibility. The comet appeared as seen through the giant 40-inch refractor at the Yerkes Observatory, perhaps the first time humans had set eyes on the 1.3 km nucleus.

The comet was not seen much after 73P dissipated from view. The comet was over 1.3AU from the Earth at the time, which was a 400-fold increase.

Comet 73P
Fragments of Comet 73P, imaged by the Spitzer Space Telescope. Credit: NASA/JPL-Caltech/W. Reach

The European Southern Observatory caught four separate fragments for what was once comet 73P, later observations by Hubble and the late-IR Spitzer Space Telescope added dozens more.

Hubble witnesses the 2006 fragmentation event. Credit: NASA/HST/STScI

When comets travel close to the Sun, they lay down debris streams of dust. If a planet happens to be in the way of the shower, you can see it in the sky. There are two great annual showers that originate from comets.

Comet 73P
The many tails of Comet 73P. Image credit and copyright: Michael Jaeger.

The Sun and planets pull debris streams into and out of the Earth's path over time. The Andromedids was once a great storm in the late 19th century, but has since fallen into obscurity.

The models show that things could get interesting later this month. There is a stream called the Tau Herculid meteors. The shower's name comes from its 1930 position near the star Tau Herculis, though in modern times the shower's position has moved into the adjacent constellation of Boötes the Herdsman.

The Herculids aren't much to look at on most years. Earth is due to cross a couple key streams in the year 2022. An encounter with streams from 1892 and 1897 can be seen in an astronomer's work. It is anyone's guess how dense these streams are. A pair of studies, one led by a Japanese team and another by a German team, both concluded that the Earth will run headlong into the 1995 stream this year.

Earth on the morning of May 31st at ~5:00 UT/1:00 AM EDT, versus the incoming Tau Herculid meteor stream. Credit: Dave Dickinson

There is a May storm in the making.

On the morning of Tuesday, May 31st at around 5:00 Universal Time or 1:00 AM Eastern Time, there is a chance of a Herculid eruption. The sky is high for Northern Hemisphere observers in the pre-dawn hours. The Moon is out of the way and will reach New on May 30th.

A ten-fold increase in the ZHR from the late 19th century streams could mean a ZHR of 140.

The Tau Herculid radiant on the morning of May 31st, as seen from the U.S. East Coast. Credit: Stellarium.

The slow shower of the Tau Herculids has an inbound speed of 16 km/second and an incoming speed of 72 km/second. You can expect a slow and stately Tau Herculid to come from near the star Arcturus and the end of the handle of the Big Dipper.

A closeup view of the Tau Herculid radiant.

We witnessed a meteorite storm from the dark deserts of Kuwait in 1998 and believe me, it is an unforgettable sight. Do you really want to miss out on the chance to see the 2022. If the skies are clear on the morning of May 31st, you can set your alarm.

There is a paper written by Joe Rao on a possible meteorite shower.

The lead image credit is from 2020. The image is copyrighted by Jeff Sullivan.