Phil Plait Talk https://www.youtube.com/watch?v=rjECbQ1r-k0 Comets Consists of a nucleus (Ice-Rock Densities g/cc) containing dust & frozen gas Tail appears when nucleus heats from Sun gases are released. Objects originate from Kuiper belt and Oort Cloud Comet nuclei Comets: Coma Appears when comet about 5AU from the sun Comet warms up releasing dust and gas Comet Dust Tail Tails form about 1AU from Sun. Released dust is pushed by radiation pressure from sun, creating a dust trail. Dust Tail Plasma (ion) tail Released gas is stripped of electrons from Suns UV light. Ions (in this case atoms lacking electrons) are pushed by ions from the sun called Solar Wind creating the plasma tail Plasma Tail Plasma tail always points away from sun. Tail is usually about Million Km long (.01AU) Size of nucleus