So there is an article here
https://amp.cnn.com/cnn/2024/10/09/science/comet-tsuchinshan-atlas-earth
It speaks about a meteor that will be here in October and not return for 80000 years. I’m just wondering, why do meteors come back?
I assume it takes a lot of force to change the trajectory of a meteor, so wouldn’t it move in the same general direction forever and never come back?
In: Planetary Science
Comets come back because they orbit the sun just like the planets do. It’s just that most of that orbit is far in the outer solar system where it’s too faint to be seen.
As a sidenote, a meteor is what you get when something from space enters the Earth’s atmosphere. When that happens, the object either burns up in the atmosphere, or hits the surface. Either way, it gets destroyed and doesn’t go anywhere.
They are orbiting the sun, just like the Earth.
Which means they are basically just going in an oval around the sun over and over.
Eventually the orbit of the Earth and the orbit of the meteor line up and it ends up close to us again.
We have only discovered a couple of objects that are from outside of the Solar system, and therefore not orbiting the sun, those *do* behavior the way you were expecting. They were here for a bit and are now gone forever. But again, those are super duper rare.
Btw, I used the term meteor because that’s what you called it. But that article is about a comet. A meteor is something that enters earths atmosphere (which means it’s going to hit the Earth and stay here). Comet would be the proper term.
Not a meteor, a meteor shower. There is a difference.
A meteor, refers to a rock that falls through Earth’s atmosphere and burns up. Sometimes a piece will make it all the way to the surface and leave a crater.
A meteor *shower* refers to an event where a bunch of tiny meteors are visible in the sky. Most of them are incredibly tiny. And there is one reliable and repeatable way to find lots of tiny particle in space. To pass through the orbit of a comet.
All of the major meteor showers are associated with a comet. Every time it orbits near to the sun, the solar rays heat it up and form the tail of dust and water leaving the comet. That dust sticks around. And when Earth passes through the dust trail, we get a meteor shower.
They are orbiting the sun, just like we are.
They just have muuuuuuch bigger orbits than Earth does.
To add to others comments, the orbit is also typically elliptical (one poster mentioned “oval”). Unlike a planetary orbit, where the distance from the sun is generally the same throughout the orbit, a comet or meteor generally has an orbit that is an ellipse, or an oval. In this case, the distance from the sun is much closer at it’s periapsis or perigee (closest point in the orbit) than it’s apoapsis or apogee (furthest point in the orbit). This also means it moves very fast comparatively, perigee vs apogee. Essentially, the sun works like a sling shot, sending the orbiting body much further away after its close proximity with the sun. But, the sun’s mighty gravity brings it back for another pass. Depending on the size of the elliptical orbit, this can be a very long time.
Basically everything you can see in space with a normal telescope or your naked eye falls into 2 categories:
1. Distant stars
2. Things in an orbit in our solar system
A meteor is something that has hit the Earth. A meteor shower is caused by a collection of things that are orbiting together coming in contact with Earth at the same time.
So what is happening here is there’s some cloud of dust or debris that is in orbit in the solar system. When it crosses paths with Earth, some of it hits Earth and creates a meteor shower.
Then both Earth and the cloud continue on their orbits until the next time they cross paths (in this case, 80,000 years from now).
The answer is twofold:
1) Comets are frozen lumps of ice and gas. Most exist in stable, regular orbits far far away from the sun in a thing called the Oort cloud.
Sometimes they get disturbed and, whilst still in orbit around the sun, their orbit is very oval and very eccentric so they go from being far far away from the sun and moving slowly to really close and moving fast
Very occasionally we will see one that coms from deep space and is just passing through and never returns
2) They have to be far and distant most of the time, or they wouldn’t survive. When they get close to the sun they evaporate and boil off and that’s what causes the comet’s tail. A comet that didn’t have a highly irregular orbit and spent time close to the sun would very quickly stop being a comet and either disappear entirely or just become a regular rocky asteroid with what’s left
A comet is in a long looping orbit around the Sun, when it comes close to the Sun it heats up and bits break off the comet leaving a trail of dust and debris behind, the Earth in its orbit around the Sun occasionally passes through the debris causing a meteor shower to occur.
There are meteors that don’t come back: these are called interstellar interlopers. They drift around in the space between galaxies for sometimes literal billions of years, only to briefly zoom through a galaxy like ours.
https://en.m.wikipedia.org/wiki/Interstellar_object
A couple years ago an interstellar interloper zoomed through our solar system. Also on wikipedia:
https://en.m.wikipedia.org/wiki/%CA%BBOumuamua
The trajectories only look straight if you’re looking at them up close. Zoom way the hell out and you’ll find they’re basically elliptical with a massive body at one focus.
>I assume it takes a lot of force to change the trajectory of a meteor, so wouldn’t it move in the same general direction forever and never come back?
The Sun’s force of gravity is tugging on it for 80,000 years to get it to “come back.”
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