This article, originally published on Wednesday, was updated Monday morning with a cloud cover forecast.
Meteor showers happen when the Earth plows through a stream of debris left in the wake of comets, asteroids or other celestial bodies. Most are the size of grains of puffed rice or small pebbles, and produce blazing displays as they burn up in our outer atmosphere. Meteor storms result when Earth enters an unusually dense and intense clustering of interplanetary debris — akin to driving through a swarm of bugs on the highway. In an instant, your windshield would be covered with smears streaking into your direction of travel.
That’s why — in the unlikely event that things line up just right — an outburst of up to 1,000 shooting stars per hour may be possible.
Where the debris is coming from
Every meteor shower is connected to an object in space. In the case of the Perseids in August, the debris comes from Comet Swift-Tuttle, while the Geminids in December are sparked by an asteroid called 3200 Phaethon. Both displays result in 50 to 100 meteors every hour when viewed beneath clear, dark skies.
With the Tau Herculid shower, the parent comet is Schwassmann-Wachmann 3 (SW3), which made its closest approach to the sun on Oct. 16, 2011. Since then, it’s been in the process of fragmenting and disintegrating.
The comet was discovered in 1930 and orbits the sun every 5.4 years. It wasn’t seen again, however, until late 1979, making a series of clandestine passes by Earth. The comet unexpectedly graced the night skies in 1995 after having apparently fractured into four pieces.
Now it has broken into dozens of pieces, and each fragment, particularly that of 1995, can result in billions of tiny bits of debris.
Some of the gravel-sized pieces of debris may stream ahead of the main comet, and on a trajectory for possible intersection with Earth’s orbit.
What are the chances it produces a meteor storm?
According to space.com, a number of astronomers are optimistic that a new meteor shower may be in the offing this year, and some even assert that meteor storm levels — corresponding to 1,000 shooting stars per hour — could be attained.
That said, astronomers don’t know how much the fragments have spread out, nor the dimensions of the debris cloud.
Meteor rates could range between one and 1,000 meteors per hour. If a meteor storm occurs, it would only last for perhaps an hour or two, and probably less.
“This is going to be an all or nothing event,” wrote Bill Cooke, who leads NASA’s Meteoroid Environment Office. “If the debris from SW3 was traveling more than 220 miles per hour when it separated from the comet, we might see a nice meteor shower. If the debris had slower ejection speeds, then nothing will make it to Earth and there will be no meteors from this comet.”
How can I watch?
If a storm occurs, you will not want to miss it.
Astronomers have pinpointed the most likely time for the peak of whatever display may or may not transpire to be around 1 a.m. Eastern time Monday night/Tuesday morning. The shower’s “radiant” point, or the part of the sky from which meteors appear to emanate, will be high in the sky over North America at that time, so there’s no specific place in the sky to look.
Of course, you’ll want to isolate yourself from bright lights or obstructions and relocate to an area with a broad view of the sky. It will be weather-permitting, of course.
In large parts of the country, clear skies should allow for favorable conditions, including much of the eastern U.S. and the Southwest. However, clouds may blanket northern New England, the northern Plains, northern Rockies, Pacific Northwest and parts of Florida, making viewing more challenging.
Past meteor storms
Meteor storms have occurred with the Leonid meteor shower, which happens each year in November. Ordinarily, the Leonids only sling a few shooting stars per hour overhead, making an unremarkable show. But once in a while, the heavens explode with sudden spikes of extreme activity and meteor rates of 100,000 per hour.
It happened again in 1833. “At Boston, the frequency of meteors was estimated to be about half that of flakes of snow in an average snowstorm,” wrote Irish astronomer Agnes Mary Clerke, who stated that the storm lasted about nine hours. Clerke placed estimates of meteor rates at the unheard-of level of as many as 240,000 shooting stars per hour. That’s more than 60 shooting stars per second.
The Leonids again dazzled on the night of Nov. 13-14, 1866. One newspaper in Malta published an eyewitness report describing the scene as “truly grand and imposing … one of the most sublime that I ever beheld.”
Another meteor storm came in 1966, igniting an equally splendid fireworks show in the United States. Eyewitness Christine Downing, who drove north of Mojave, Calif., saw a couple of shooting stars every five minutes, which “at the time … seemed extraordinary.” At 12:30 a.m., it began “raining stars,” and by 2 a.m. “it was a ‘blizzard.’ ”
Her description, which can be read in full on a NASA Web page, is one of many from that night. “There was the unnerving feeling that the mountains were being set on fire,” Downing wrote. “Falling stars filled the entire sky to the horizon, yet it was silent.”
Additional, tamer outbursts took place in 1999 and 2001.
There aren’t any meteor storms from the Leonids or any other shower explicitly predicted in our lifetimes, nor are we likely to encounter anything close to what generations of the past saw — but next week might offer a taste.
An earlier version of this article incorrectly said that meteor storms result when Earth enters a clustering of interstellar debris. The debris comes from within the Earth's solar system.