Relative to the sun, the gaseous component of comet tails..the part that you see..points downwind of the solar wind at the location of the comet. This is very nearly in a direction that is opposite to the direction of the sun, but may differ by several degrees depending on how the local solar wind velocity vector is oriented. In general, the dust tail points along the comet's orbit. The gas tail points downwind of the solar wind which is a spiral-shaped flow of gas. The direction these tails point depend entirely on which planet you are standing on and viewing the actual dust/gas motions in the tail. The gas component generally points in the opposite direction of the sun to rather high accuracy, but its specific direction depends on the solar wind. Near the sun...direct radiation pressure may dominate and make the gas flow exactly opposite to the solar direction.