Then my point stands. The point is not about plasma in a vacuum. My point is that the material that fluoresces in the tail of the comet had to get to a point in space a long long way from the comet. If that one molecule is fluorescing all the way on it’s trip, then the tail must appear curved. It doesn’t look curved so we must assume that it is not fluorescing for most of the trip. This dark material must have been ejected ahead of the apparent motion of the tail so as to be in position to fluoresce when it intersects with the triggering event. The triggering event could travel from the comet to the tail at the speed of light, but by my understanding not in excess of it. But the material itself must be vastly slower than the speed of light. Even at the speed of the solar wind lets say 400kph it takes 5 hours to cover the distance to the end of a 10 million kilometers long. But in five hours the tail has moved ahead of where the material ejected 5 hours earlier is headed. Thus the material must have been aimed ahead of the apparent tail to arrive at its ion emitting destination. This being the case, the model of the anatomy of a comet should be revised to show these ejected pieces of matter. They must be ejected from all directions with the vast majority never intersecting with the triggering event that will cause it to emit Ions and Fluoresce.
The difference in time between when the material destined to fluoresce in the tail of the comet leaves the coma and intersects with the triggering event has to be very great. It must be very great as it has to move in a direction sideways to the solar wind. This means the model of the comet must be revised to show this material moving away from the comet in all directions.
Now for the triggering event which causes the ion emission in the apparent tail. If the triggering event is indeed photons it still takes quite a few seconds to cover the 10 million kilometers to the tail. And then since the far end of the tail may at times be many millions of miles further away from the observer than the head end of the tail it takes the photons emitted by the ion emission at the end of the tail quite a few seconds longer to make it back to the earth bound observer. This means again that the tail should appear curved as in an arc. But it does not, therefore the entire premise of the straight line tail must be rejected. Only if the distance is the same or nearly so from every point on the tail to the observer can it appear straight. Thus my postulations that there must be a method for all points along the apparent tail to be approximately equidistant from the observer. NO MATTER WHERE IN SPACE THAT OBSERVER HAPPENS TO BE.
Now the only method I am aware of that can cause this effect has to do with suspended ice crystals that are formed when water vapor, not water, water vapor freezes. And the only way they can give this effect is if they are in a very low density cloud surrounding the comet.
I do not know that they exist, I am postulating that they must exist for the tail on the comet to appear straight.
The Ice crystals I am accustomed to viewing are earth bound and I admit, I do not understand everything about them. But they can make it appear as if a beam of light is shining up into space where no beam exists. They do it in three dimensions.
I am postulating that this same optical apparition could be at least partially responsible for the tail on the comet to appear in the shadow of the comet, where no beam of light exists.
It is worth considering. That is all I am saying.