Let's space rock and roll: Here's why and how meteor showers happen

Meteor showers are an annual occurrence, all because of comets' orbits


The Perseid meteor shower, one of the most visible of 2018, took place Sunday night through Monday morning. Experts said 60 to 70 meteors were visible per hour to the naked eye.

If you watched the shower, or if you didn't and wondered what was so special about some space rocks, you may now be wondering -- what exactly is a meteor shower, and what makes it happen? According to NASA, it turns out that the answer has more to it than just brightly-colored flying space rocks.

What is a meteor shower?

NASA defines a meteor as "a space rock—or meteoroid—that enters Earth's atmosphere." As the rock falls toward Earth, the air rushing against the rock heats it, creating a glowing hot trail of air as the rock zips through the atmosphere. This is what we commonly are able to perceive as a shooting star.

A meteor shower occurs when Earth encounters many meteors at once, sometimes visible to stargazers as upward of 100 per hour. The main factors in when a meteor shower will occur are comets, icy space bodies that orbit the sun. The meteors left behind from those orbits specifically are directly responsible for Earth's visible meteor showers.

How do meteor showers happen?

Whereas Earth and the other planets in its solar system follow mostly-linear orbits around the sun, comets' orbits are often slanted. Many are at angle to Earth's orbit, which is why most meteor showers occur yearly. The orbit of Comet Swift-Tuttle, the comet responsible for the Perseid shower, is nearly perpendicular to Earth's orbit.

As comets get closer to the sun, their frozen surfaces begin to boil off, leaving dust and rock in their wakes. This debris is left in the comet's path. As Earth makes its yearly journey around the sun, it moves through these clouds of comet debris, introducing many meteors at once into the atmosphere, resulting in what we know as a meteor shower.


The meteors range in size from as small as a dust particle to up to a boulder. Most of them burn so hot that they disintegrate as they enter Earth's atmosphere.

The bright streaks left behind by meteors have the potential to appear anywhere in the sky, but all of the meteors' tails will always originate from one point, called the radiant. This is because all of the meteors are approaching Earth from the same point, even though perspective may make them appear more skewed as they get closer.

When is each meteor shower?

Armed with this knowledge, if you missed the Perseid shower, you know there is no need to fear. According to the American Meteor Society lists 12 different annual meteor showers that will be visible on Earth. 

The most active showers are:

Quadrantids, next active Jan. 1 through Jan. 10 in 2019.

Lyrids, next active April 19 through April 25 in 2019.

Perseids, often most active July 13 through Aug. 26.

Orionids, next active Sep. 23 to Nov. 27, 2018.

Leonids, next active Nov. 5 to Nov. 30, 2018.

Geminids, next active Dec. 4th through Dec. 16, 2018.