The Rare Double Meteor Shower Explained

Alongside solar and lunar eclipses, meteor showers are popular astronomical events around the world. While more than 900 of these phenomena happen every year, only about 30 of them can be seen. However, the most remarkable of these cases is the double meteor shower.

Meteor showers occur when meteors fall through the atmosphere. Such events are generally associated with comets that orbit the sun, occurring when the Earth's orbit intersects with their paths and the meteoroid streams they leave behind. In the rare case of a double meteor shower, the Earth crosses through the paths of two comets at around the same time. As a result, more comet debris falls through the Earth's atmosphere, resulting in more streaks of light in the sky than normal.

As of writing, the most recent occurrence of a double meteor shower was at the end of July 2024. The Alpha Capricornids were active from July 3 to August 15, while the Southern Delta Aquariids were active from July 12 to August 23. During the July 30 to 31 peak, the moon was either waning or only a thin crescent, so it didn't interfere much during the early-morning viewing hours — the best time to watch well over 20 meteors per hour as the Earth rotated into the meteoroid stream.

To better understand the rare double meteor shower, it can help to learn more about regular meteor showers. As meteoroids before entering Earth's atmosphere, meteors are made up of iron or rock and orbit the Sun. Aside from shedding comets, meteoroids can come from the rocky debris of celestial collisions, such as asteroids crashing into each other.

The special part, though, happens when a meteoroid enters Earth's atmosphere: Friction with air particles makes the gases around the debris (now called a meteor) burn and glow, creating a stream of light as it falls toward the ground. The bigger the meteor and the faster it travels, the longer and brighter it will glow — sometimes for several minutes. When it comes to the individual meteors that streak through the sky, they're referred to as shooting stars. They only become a meteor shower when there are an abundance of meteors, which can fall at a rate ranging from 10 to 100 per hour.

Since comets have orbits of their own, scientists can predict when meteor showers occur. However, the number of meteors can vary and be harder to predict because those aspects depend on when the comets shed debris and how long it lingers in space before Earth passes through it. Most meteors disintegrate during their descent to Earth's surface, but there are times when large ones survive the entry, at which point they are called meteorites.