# Can a meteor shower have a interval greater than 1 year?

Most meteor showers are yearly events. In the manga "SoSo no Frieren" the characters experience a meteor shower that happens only once every fifty years. The story does not take place on Earth, though.

Is this plausible? Wikipedia says,

A meteor shower results from an interaction between a planet, such as Earth, and streams of debris from a comet.

Perhaps from a comet with a period of 50 years, when this stream of debris crosses the planet's orbit.

Is this interpretation feasible? Is there any known meteor shower with a period greater than 1 year?

• Are you seeking an answer based on what we've observed in our solar system? In other words, an answer to "is there any meteor shower which the Earth experiences which has a period of greater than a year?" If so, then Astronomy is probably your best choice for where to ask, although the answer you got here covers it. If your question is "I'm building a fictional world; how could that world have a meteor shower which has a period of 50 years during the few thousand years surrounding the time I'm interested in?" If so, then Worldbuilding may be your best choice for where to ask. Sep 21, 2022 at 23:40

This is really more of a question for Astronomy.SE, in general this doesn't happen, but circumstances can work out that it does, see the updated last few paragraphs.

Every meteor shower with an identified cometary source comes from a comet with a period longer than one year, but the meteor showers are still annual. The Eta Aquarids and the Orionids are sourced from Halley's Comet, and it has a period of 75-76 years.

The debris and dust shed by the comet as it orbits (at least, that part of it ejected fast enough to escape the comet's meager gravity) winds up in an orbit around the Sun; generally an orbit close to the comet's orbit, maybe a little smaller, maybe a little larger, maybe a tiny bit off-inclination. The result is an orbiting swarm of dust, gas and debris surrounding the orbit of the comet, and when the Earth passes through the area of this elliptical torus, that's when some of it passes close enough to hit the atmosphere, and we see meteor showers.

That said, the meteor showers themselves are typically more significant when a passage of the generator comet is recent.

And credit to Mark, there are meteor showers that do exhibit the requested behavior. Comet 55P/Tempel-Tuttle is the source of the Leonid meteorite shower, and it has an orbit that gets under 1.5 million kilometers from Earth's orbit. As a result, the recently-shed dust and gas doesn't have to disperse far from the comet's orbit to encounter Earth. So with most comets as this dust spreads out, the individual effects of each perhelion passage are lost in the noise, but with the Leonids and Tempel-Tuttle, the nearness of the passage means that the perihelion density clumps are better defined when Earth encounters them, resulting in a spectacular jump in meteorite frequency a bit over every 33 years (the orbital period of the comet), with a far higher proportion of meteorites than usual.

The last such peak were the 1999-2001 storms. 2022 is predicted to produce a higher-than-average level, but not meteor-storm level.

Given a similar setup, it's not hard to imagine a situation where the peak every 50 years on a hypothetical 50-year comet gets noticed by everyone in a fantasy setting, but only those who really know their astronomy notice that a lesser version happens every year. Especially if the last few times it happened, things kicked up into the dozens of thousands of meteors per hour range.

• @MichaelW. it is the Earth's orbit that causes the interval to be 1 year, if the comet's orbit changes, the Earth will still pass through the debris left behind once per year (until all of the debris is gone). Sep 21, 2022 at 20:18
• i.imgur.com/LjUeU0l.png (my understanding of this nice answer, in a badly drawn picture format) Sep 21, 2022 at 23:42
• I think you're underselling things with your last paragraph. The Leonid metors, for example, can exhibit a thousand-fold variation in the number of meteors, giving the effect of a 33-year cycle.
– Mark
Sep 22, 2022 at 0:14
• Would a more elliptical planetary orbit allow this? Earth is more or less in the same place every time it comes around, but eg Mercury might manage to miss the dust cloud one time around and hit it the next Sep 22, 2022 at 10:10
• @Andrew Even elliptical orbits sweep through the same region of space relative to what they're orbiting, every orbit. And the comets that produce these meteor showers are also already in very elliptical orbits. If the two orbits come close enough that a notable meteor shower occurs on the planet, they're going to keep coming close enough until the comet's orbit is changed by something else, or the comet stops orbiting the star, and even then, the debris torus will remain for some time. Mercury's orbit does precess due to general relativity, but nowhere near fast enough to avoid this. Sep 22, 2022 at 10:24