Fun vacation spots for Image credit Crawford Library of the Royal Observatory, Edinburgh, Scotland. Gas tails are formed when the electrically charged gas particles that exploded toward the Sun from the nucleus are pushed by the solar wind directly back behind the nucleus. Because of this, gas tails are generally straight, narrow, and point directly away from the Sun. The sunlight causes them to fluoresce. Dust tails are formed when small dust particles expelled from the comet’s nucleus toward the Sun are pushed behind the coma by solar radiation pressure. Because dust particles travel more slowly than gas particles, they lag behind the comet, with the result that dust tails tend to be more curved and broad than gas tails and not directly anti-solar, but rather angled back toward the direction from which the comet has just come fig. The section of the dust tail farthest from the coma is less dense, less bright, and more curved. Fun vacation spots 2016.