What Is a Meteor Shower?

The 2012 Geminids meteor shower in Thailand.
The 2012 Geminids meteor shower in Thailand.

What Is a Meteor Shower?

Meteor showers can be seen in the night sky, appearing as glowing trails of light, which many people often refer to as falling or shooting stars. This phenomenon occurs at specific times during the year, although it may happen in much smaller numbers as well, known as sporadic meteors.

Despite the common nomenclature used to describe this astronomic occurrence, a meteor shower is not actually a falling star. Instead, meteor showers are caused by comets, which are dusty balls of ice that travel very close around the sun. As the ice heats up, many tiny pieces break away and continue to orbit the sun. This circular trail may cross into the path of several planets, including Earth. As Earth crosses into this path of debris, the tiny particles are heated up by the high speed and friction caused by entering the Earth’s atmosphere. Most of these particles burn up before reaching land, but the process creates glowing streaks visible to humans below.

Meteor showers can have a duration of just a few days, or may last for as long as weeks, depending on the width of the comet trail in orbit. When Earth makes its complete orbit the following year, it again crosses paths with the space debris, allowing people on Earth to see the meteor shower. This consistency allows scientists to predict meteor shower dates, which turns them into annual events. Some of the most well-known meteor showers seen from Earth are listed below.

Perseid Meteor Shower

The Perseid meteor shower occurs every year between July 17 and August 24, with peak activity generally falling on August 12 or August 13. During its peak, observers have reported sighting between 60 and 100 light streaks per hour, making the Perseid shower one of the brightest meteor displays. This meteor shower is made up of debris from the Comet Swift-Tuttle, which has a width of greater than 16 miles and an orbital period of 133 years. Its name, however, is derived from the Perseid constellation, which is named for the Greek god Perseus. This meteor shower is primarily visible in the northern hemisphere, although fewer meteors have been sighted in the southern hemisphere.

Orionid Meteor Shower

The Orionid meteor shower occurs every year in October, with peak activity generally falling between October 21 and 22. Observers report sighting between 50 and 70 streaks of light per hour during this time frame. The Orionid meteor shower is made up of debris from Halley's Comet, which has a width of greater than 6.8 miles and an orbital period of between 74 and 79 years. Its name is derived from the Orion constellation, which is named for a character from Greek mythology.

Taurid Meteor Shower

The Taurid meteor shower can be seen in both the northern and southern hemispheres. In the northern hemisphere, it is visible between October 20 and December 10, and in the southern hemisphere it is visible between September 10 and November 20. The Taurid meteor shower is made up of debris from the Comet Encke, which is almost 3 miles in diameter and has an orbital period of 3.3 years. Recently, researchers have discovered an additional trail of Taurid meteors that includes 2 particularly large asteroids, which measure between 650 and 900 feet in diameter. Scientists calculate that these asteroids could make contact with Earth’s surface in 2022, 2025, 2032, and 2039. These asteroids are listed as potentially hazardous by the International Astronomical Union and are believed to be able to generate enough force on impact to destroy entire continents.

Geminids Meteor Shower

The Geminids meteor shower occurs each year between December 7 and December 17. Research indicates that the number of light trails left by this shower may be increasing every year, with the highest number of sightings recorded at between 120 and 160 per hour. This meteor shower is one of the only annual events not caused by a comet trail. Instead, the Geminids originates from a rock comet, which is a relatively rare astrological body made of a rock nucleus. This means that the light trails seen during the shower are not from dusty bits of ice, but rather pieces of rock. This rock comet, which moves closer to the sun than any other cosmic body, is known as the 3200 Phaethon.

Lyrid Meteor Shower

The Lyrid meteor shower takes place each year between April 16 and April 26, with peak activity typically occurring on April 22. On this day, the average number of light streaks observed is approximately 10, although some individuals have reported seeing as many as 20 at a time. The Lyrid meteor shower is made up of debris from the Comet C/1861 G1 Thatcher, which has an orbit period of around 415 years. The meteor shower has a recorded history of over 2,600 years.

Draconid Meteor Shower

The Draconid meteor shower occurs every year between October 6 and October 10. Its heaviest activity can usually be seen on October 8, with extreme spikes in activity in 1933, 1946, 1998, 2005, and 2012. During these years, Earth passed through the heaviest area of comet debris. This debris originates from the Comet 21P/Giacobini-Zinner, which is 1.24 miles in diameter and has an orbit period of approximately 6.6 years. It can be seen with the best clarity from the northern hemisphere and just after sunset, which is unique since most meteor showers are strongest before dawn.

When Is the Next Meteor Shower?

Aside from the meteor showers noted above, the next shower expected to occur in 2017 is the Andromedid meteor shower. This event occurs from November 25 to November 27, at an average rate of 5 meteors visible per hour.

Meteor showers are best viewed outside of cities, as artificial lights can obstruct the view of the night sky. Meteor shower watchers should try to locate the hub from which the shower originates. Most meteors will be seen between this hub and the sky directly above. Generally speaking, the hours between midnight and dawn provide the best viewing capabilities, as this is when the viewer’s location faces the Earth’s orbital direction.


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