What Are Meteor Storms?
Meteors are light phenomena that occur when a piece of cosmic rock (meteoroid) tears through our atmosphere. Sometimes, many rocks can accompany a single rock. However, if there are thousands of rocks falling in nearly parallel trajectories, we call that a meteor storm.
Shortly after the discovery of meteors in general, we discovered storms. They are one of the rarest celestial events the humanity has ever witnessed, and therefore they are quite sought-after. But witnessing a meteor storm is not exactly easy. Their main characteristics are a high meteor concentration, brevity of duration, and unpredictable conditions required for facilitation. In other words, it is an event that occurs rarely, might end abruptly, and we never know when it will happen again.
From an astronomer’s point of view, research was difficult to conduct due to unpredictability. You cannot exactly orchestrate meteor showers, let alone storms, in your lab, right? Thankfully, showers that happen several times during the year provide priceless insight. We even use calendars for shower predictions with special highlights for potential storms. Some showers are so potent that their peak is always a storm, while others are not that powerful.
As we already explained, storms are massive outbursts of meteors in the sky. The terms used for explaining both celestial phenomena are self-explanatory. Showers are long outbursts of cometary debris that enters our atmosphere at high velocities, while storms are massive showers. Most meteors are micrometeorites, meaning that they have zero chance to reach the surface. When they fall in clusters (or mega clusters), they create a celestial event on a massive scale that we see as a “star storm” – millions of grain-like fragments that cover the sky. Storms are classified as large outbursts that produce more than 1,000 meteors in an hour.
The peak of massive showers such as Leonids might be labeled as storms. For example, the one shower (and storm) that catapulted meteoritics into mainstream culture was the Leonid from 1833. Even though we are now aware which comet is responsible for that storm, why it happens, and where it happens, people back then were very confused. For them, celestial events have ties with religion and mythology, while scientists regarded them as atmospheric phenomena. Olmsted was one of the first astronomers to distinguish meteors as rocks from outer space and classify the event as extraterrestrial. Soon after, meteors, showers, and storms entered the vocabulary of modern astronomers. Today, Leonids are still the biggest storms in astronomy, along with Andromedids.
Leonids are probably the most famous meteoritic phenomena in both astronomical and non-astronomical circles. Amateurs and professionals are observing and keeping track of the storm’s parent comet Temple-Tuttle. Through intricate research, experts uncovered that the comet crosses its perihelion every 33 years. So, it is neither rare nor frequent. One Leonid storm still holds the record for the largest meteor storm in human history. In 1966, after waiting more than a century for a proper display, Leonid storm lighted up the sky on November 17. That single event produced around 144,000 meteors per hour. Leonids are also among the fastest meteor showers, with meteors flying through the atmosphere at 72 km/sec. If you want to learn more about Leonids, have a look at our page dedicated to meteor showers.
Andromedid or Bielid storms are one of two massive November meteor events. The shower is associated with the comet 3D/Biela, which unfortunately disintegrated in 1846. The comet belonged to the Jupiter family. Several astronomers recorded sightings independently from 1772 to 1806. But it was Biela who finally defined it as periodic in 1826. As a consequence of its disintegration in 1846, the comet split into two parts and neither has been seen since.
However, the disintegration brought about impressive celestial shows, particularly in 1885. That specific meteor event is also one of the biggest Andromedid showers and storms. The peak occurred on the 27th of November, with 13,000 meteors per hour marking a proper meteor storm. However, because the comet is no longer in existence and its remnants are mainly floating in space, it is hard to make predictions. Orbital perturbations are frequent, so debris can rarely cross Earth’s path in a manner that is suitable for a storm. The best example is the shower from 1940 when only 30 meteors per hour were visible.
How Can We Predict Storms?
This one question is one of the most asked ones ever since the inception of astronomy. While early predictions had somewhat primitive foundations (and little to no scientific basis), the situation is different now. With the help of elaborate studies, observations, and high-level calculations, we can create outlines and work out patterns of comet appearances. Halley’s comet returns to us every 76 years, but that is just one out of thousands (or millions, more likely) comets that can pass Earth.
Modern predictions have more sophisticated foundations in science than before. Astronomers predict with great accuracy the comets and meteors using trajectories and theory. Based on the comet trajectory, we can guess the possible trajectories of meteors as they are debris left behind by the comet. The optimal model for calculation employs debris release rate (size, direction, mass, and velocity of release included) and gravitational forces that influence the trajectories. Another essential piece of the puzzle is Earth’s movement and rotation. Once we take everything into account, we can determine the most probable outcome and forecast for the future.
Storms are a hot topic in the astronomical community. Showers with unusual developments and heavy concentrations of cometary debris are an endless source of information for young scientists. If you wish to inform more about this specific celestial event, you can always visit the American Meteor Society (AMS). There you will find all kinds of fun facts regarding meteors and meteoroids, as well as fireballs and asteroids.
One excellent source for further space exploration is the International Meteor Organization. IMO hosts numerous programs where you can learn more about observational techniques. Speaking of observation, an expert in observing celestial occurrences is certainly NASA.NASA has several branches that are dedicated to individual fields of study, including the one that specializes in small Solar System bodies like meteors and meteoroids.