How to see Tau Herculid, the best eruption of the century

With a little cosmic luck, we could potentially have a meteor storm of epic proportions next Monday night/Tuesday morning. We recently wrote about the possibility of an eruption of the Tau Herculids on the night of May 30-31. Since we’ve been out of the shower for a little less than a week now, let’s take a look at the shower outlook, what happened during meteor storms of yore, and more.

tau Herculids: The story so far

The shower’s source is short-period comet 73P/Schwassmann-Wachmann 3. Despite its name, the radiant for the tau Herculides has now drifted from Hercules to the adjacent constellation Boötes the Herder. Unfortunately, it’s also problematic to call the shower the ‘Boötids’, as there’s already a June meteor shower of the same name. Today, the shower radiant is about 8 degrees from the bright star Arcturus, toward the globular cluster Messier 3 and Alkaid (Eta Ursae Majoris) at the tip of the handle of the Big Dipper asterism.

What really gets scientists excited about a meteor shower is Earth’s encounter in 2022 with the comet’s 1995 fragmentation flow. This event dramatically increased the comet’s brightness by a factor of 400. Now next week the comet will be nowhere near Earth — it’s actually 1.4 astronomical units (AU) away, in fact — but the 1995 event should have set off quite a particle stream for our beautiful planet.

At the time of writing, the American Meteor Shower (AMS) has refined the key meeting time to 4:45-5:17 Universal Time (UT) / 12:45-1:17 AM US Eastern Time EDT on Tuesday morning, May 31 or 9 :45-10:17 PM Pacific Time PDT on the evening of Monday, May 30. The radiant will be right on the zenith for Baja California around this time, although most of the Americas will be well placed to witness an uptick in meteor activity. The moon also reaches New the day before on May 30…another plus.

If we get a 10-fold increase in the tau herculids, we might see a Zenithal hourly rate (ZHR) of ~140 meteors per hour – similar to the annual Geminids or Perseids. If we get to a 100-fold or higher increase… well, it could get interesting.

But first, a few caveats are in order. It is not known how much and in which direction Comet 73P ejected debris during the 1995 event: this could contribute to a more intense (or weaker) storm than expected. Also, the tau Herculid current is approaching Earth from behind, making them a slower squall that needs larger particles than usual to light up the sky. Finally, remember that ZHR numbers are an ideal speed assuming a dark sky with the radiant directly overhead… most observers will actually see less.

Anatomy of a Meteor Storm

Usually, a ZHR of 1000 or more is considered the informal boundary for a meteor storm versus a meager meteor shower. Typically, during the annual Geminids or Perseids, you’ll see a meteor or two about once a minute; at a speed of more than a thousand per hour, you see a meteor every few seconds, including bright fireballs. I remember watching the 1998 Leonids reach storm level just before dawn, with so many bolids lighting up the Kuwaiti desert that you knew there were meteors missing right behind you. Observers who witnessed the Leonids of 1966, which peaked at a staggering 80,000 (!) meteors per hour, noted how the stream emanating from the radiant gave viewers a real sense of our planet’s movement through space, a whole ‘Star Trek‘warp speed-like effect.

In recent years, we have seen the 2012 Giacobinids (Draconids) flirt with storm levels, with a ZHR of over ~900 per hour. The anatomy of the 2022 tau Herculids bears some resemblance to another major storm of the past: the now-defunct Andromedids. The source of this squall is the now-defunct ‘lost comet’ 3D/Biela, which is believed to have fragmented and spawned some of the great meteor storms of the late 1800s.

An image of the great Leonid Meteor Storm from 1833.Public domain image

Observing a Meteor Storm

You don’t need any special equipment to watch a meteor storm: just clear skies and patience. Our typical strategy is to watch for about ten minutes: if I see meteors, I keep looking. European and British observers may also want to start watching a few hours earlier. Meteor storms do not read forecasts and can always start a little earlier than expected.

You can even hear meteors pinging over a radio tuned to a free frequency on the FM dial. Make sure you dress warmly (even in May), bring a lawn chair and bug spray and find as dark an observation spot as possible… also bring a few friends to view different parts of the sky and the chance of the catching meteors as they fly by. In fact, bright fireballs have been known to “sizzle” via a strange phenomenon known as electrophonic sound.

At the time of writing, the cloudy outlook for the contiguous United States appears broadly favorable. It might be worth checking out the action on NASA’s all-sky meteor camera network when it’s cloudy.

Imagine a meteor storm as simple as setting up a tripod-mounted DSLR camera with a wide-angle lens, setting the focus and priority to Manual/Bulb settings, then taking a few quick test shots to check the ISO/exposure /f- quit the air condition settings and see what pops up. I like to use an intervalometer to automate the process and simply set it up to take sequential sets of photos so I can sit back and visually view the shower.

Also, be sure to count meteors and report what you see to the International Meteor Organization (IMO). This data will greatly contribute to meteor science and the modeling of meteor flows and showers in the future.

Finally, be patient during your meteor wake. You may not see anything at all… or witness the spectacle of a lifetime. Clear skies, and good luck!

This article was originally published on Universe today by Nancy Atkinson. Read the original article here.

Leave a Reply

Your email address will not be published.