Eduardo Alvarez and Robert Buchheim developed a 4-point method to calculate the diurnal parallax of these objects, a computation which was first done by Regiomontanus. They’re not planets, but the “exo” type of these objects have been suggested as a major source of white dwarf pollution. The Stardust probe was the most recent expedition to one of these objects named Tempel 1, after (-5[1])achieving its originally intended goal (10[1])of collecting dust samples from one of these objects named Wild 2. One popular hypothesis about these objects by Fred Whipple describes them as “dirty snowballs.” (10[3])For 10 points, (10[1])name these celestial objects that are made of ice and have a tail. ■END■