I’ve always believed that a comet’s tail exists as a result of the forces of the solar wind and other ejecta from the sun, so that the tail always points away from the sun. I notice on this video (http://science.nasa.gov/media/medialibrary/2013/11/29/weird_anim2.gif) that as the comet emerges from the sun-blocking disc, its tail gets swept in a direction that’s almost perpendicular to the direction it’s moving, and hence almost perpendicular to any line drawn from the sun to the comet. What forces would cause the tail of the comet, or any outgassing, to be directed across the lines of force that the solar winds exert? Why doesn’t the comet look like a comet “should” as it moves away from the sun?
Looks to me as the tail is beginning to show the effects of the solar wind. A later video would probably show it away from the sun. The action of the solar wind is not instantaneous.
Comets generally have two tails: the ion tail, pointing directly away from the Sun, and the dust tail, which points away from the sun a bit as well as being affected by the direction of the comet’s movement and outgassing etc
I would guess the close encounter with the sun has caused significant outgassing, and the dust launched by that takes some time to be pushed by the radiation pressure (unlike the ion tail, which the solar wind affects a lot more strongly)
It appears that the thing evaporated before it reached the Sun, and is now only visible on very high powered telescopes.
I think the tail is mostly pointing away, you just have to picture it in 3 dimensions. The comet is moving from our point of view towards the sun so the tail is pointing more or less our direction. Then it swings around and is pointing away from us - at least that’s how I interpret the image.
If the comet is traveling as fast as the solar wind, then the tail wouldn’t blow past it.
Watch the GIF. It shows pretty much what I’d expect for a comet moving nearly the speed of the solar wind.
As mentioned above, there are two tails, ion and dust. The ion one is affected more quickly, the dust one takes a bit longer to get blown past the comet.
It seems to me the direction of the tail would be the sum of the vectors from the direction and force of the solar wind and the direction and momentum of the particles in the tail. When the direction of the comet is changing fast as it is at perihelion, the momentum of the material in the tail might be a significant component. Then as the comet moves away and the solar wind has more time to act, the tail would eventually straighten in a direction away from the sun.
Imagine a streamer blowing in front of a circle of fans. Now swing the thing the streamer is attached to quickly in a circle around the fans. If you do it fast enough, the streamer isn’t going to stay straight - it will have a force vector tangent to the circle its ‘nucleus’ is making around the fans, and a force vector acting perpendicularly to that from the fan wind. With a solid streamer the effect would be to force it into some kind of arc. If the ‘streamer’ was just a conglomeration of unconnected particles, you might get the fan-like shape we saw of the tail as the comet came around the sun after perihelion.