United States Army Materiel Command. The U.S. Army Materiel Command (AMC) is the primary provider of materiel to the United States Army. The Command's mission includes the research & development of weapons systems as well as maintenance and parts distribution.
A comet is a small, icy object that orbits the sun and has a long tail of gas. Some comets can be seen from Earth every few years, while others pass by once in a person's lifetime. Comets are made of ice, dust, and tiny pieces of rock, but to people on Earth, they look like streaks or smudges across the night sky.
Halley's Comet. Halley's Comet or Comet Halley, officially designated 1P/Halley, is a short-period comet visible from Earth every 75â76 years. Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and the only naked-eye comet that might appear twice in a human lifetime.