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So I will shortly write a page about the topic of meteor calculations and wanted to review the practice on the calculations page mostly in light of some approachs I saw recently.
With that lets get on topic:
1. Calculating speed by approximating meteor distance from earth
This is a method I have seen used often recently. The idea of it is that a meteor should come out of space, so it should generally be a certain distance away from earth (there are several approachs to estimating which distance, which I will not name further). By knowing the distance and the time the meteor required to reach earth one can figure out its speed and by that its kinetic energy.
Now this method would probably be what first comes to mind when one wants to calculate meteor speed, but I don't agree with it.
That has several reasons. For one thing most meteor summonings, especially if they are common techniques of characters, are almost instantanous. So they would always give very big results.
The second reason is that the likelyhood of actually finding such big meteors or several small meteors anywhere close to earth is extremely unlikely. So the distance you would likely have to pull a meteor from is even a lot larger than the distance most of the before mentioned estimations give. Take a look here for example. In all of March only 2 objects pass earth closer than the moon and looking at the table as a whole most of the time pulling meteors from space just like that might as well make them FTL or at least high relativistic.
So I really doubt a method like this would return reliable and reasonable values, especially if the one using it can do so freely at any time.
2. The absolute standard
The method that likely doesn't need to be discussed is that if the speed of a meteor can be determined by some method we can just use that.
3. The minimum value 1
If otherwise no speed can be determined, I believe the minimum speed of objects that hit earth can be used. That is 11 km/s. Note that this is the speed for befor entering earths athmosphere, athmospheric effects can slow small meteroids down. This calculator consideres that (under the athmospheric effects section), but for many really small one it predicts them to explode to pieces before hitting earth, so in that cases this shouldn't be used. Usually 11 km/s is a solid estimation though and can be used like that in my opinion.
4. The minimum value 2
Something interesting I found here (topic dark flight) is that meteroids apparently stop glowing once they slow down below 2-4 km/s. So for burning meteors and the like we could assume them to be faster than that and for not glowing ones that they are slower than that.
I am uncertain if we should use that to determine speed or not... Well, we can use it for cases where it is questionable if meteors move at meteor speed.
So my suggestion on how to estimate speed of meteors is:
1. If you can calculate it somehow, use that.
2. If you can't calculate it, but the technique uses something that can be assumed to have natural meteor speed use 11 km/s.
3. If its questionable wether or not the meteor has typical meteor speed and you can not calculate its speed otherwise, assume above 2-4 km/s if its burning/ablation occured and below 2-4 km/s if it is not.
With that lets get on topic:
1. Calculating speed by approximating meteor distance from earth
This is a method I have seen used often recently. The idea of it is that a meteor should come out of space, so it should generally be a certain distance away from earth (there are several approachs to estimating which distance, which I will not name further). By knowing the distance and the time the meteor required to reach earth one can figure out its speed and by that its kinetic energy.
Now this method would probably be what first comes to mind when one wants to calculate meteor speed, but I don't agree with it.
That has several reasons. For one thing most meteor summonings, especially if they are common techniques of characters, are almost instantanous. So they would always give very big results.
The second reason is that the likelyhood of actually finding such big meteors or several small meteors anywhere close to earth is extremely unlikely. So the distance you would likely have to pull a meteor from is even a lot larger than the distance most of the before mentioned estimations give. Take a look here for example. In all of March only 2 objects pass earth closer than the moon and looking at the table as a whole most of the time pulling meteors from space just like that might as well make them FTL or at least high relativistic.
So I really doubt a method like this would return reliable and reasonable values, especially if the one using it can do so freely at any time.
2. The absolute standard
The method that likely doesn't need to be discussed is that if the speed of a meteor can be determined by some method we can just use that.
3. The minimum value 1
If otherwise no speed can be determined, I believe the minimum speed of objects that hit earth can be used. That is 11 km/s. Note that this is the speed for befor entering earths athmosphere, athmospheric effects can slow small meteroids down. This calculator consideres that (under the athmospheric effects section), but for many really small one it predicts them to explode to pieces before hitting earth, so in that cases this shouldn't be used. Usually 11 km/s is a solid estimation though and can be used like that in my opinion.
4. The minimum value 2
Something interesting I found here (topic dark flight) is that meteroids apparently stop glowing once they slow down below 2-4 km/s. So for burning meteors and the like we could assume them to be faster than that and for not glowing ones that they are slower than that.
I am uncertain if we should use that to determine speed or not... Well, we can use it for cases where it is questionable if meteors move at meteor speed.
So my suggestion on how to estimate speed of meteors is:
1. If you can calculate it somehow, use that.
2. If you can't calculate it, but the technique uses something that can be assumed to have natural meteor speed use 11 km/s.
3. If its questionable wether or not the meteor has typical meteor speed and you can not calculate its speed otherwise, assume above 2-4 km/s if its burning/ablation occured and below 2-4 km/s if it is not.
