... nucleus is the solid part of acomet, in the middle of the comet’shead.• The coma is the gassy atmospherethat surrounds the nucleus when the comet nears the Sun.• The tail is the long, bright ... out from the center of the galaxy. These are the Norma Arm, the Scutum-Crux Arm, the Sagittarius Arm, and the Perseus Arm. The Sunlies in a small arm called the Orion Arm, alsocalled the Local ... headstowards the primary mirror. 2. It is then reflected up the tube to the smaller, secondarymirror.3. The light is then reflectedback down the tube, through ahole in the primary, to the focus(located...