1. Comets By: Juan Alvarado and Cameron Murry

2. Rotation and Revolution of Halley’s Comet • In 1705 Edmond Halley predicted (using Newton‘s newly formulated laws of motion) that the comet seen in 1531, 1607, and 1682 would return in 1758 (which was after his death). • The comet did return when he predicted it would. • The comet was later named in his honor. • The average period of Halley's orbit is 76 years but you cannot calculate the dates of its reappearances by simply subtracting multiples of 76 years from 1986. • The gravitational pull of the major planets alters the orbital period from revolution to revolution. • Non-gravitational effects (such as the reaction from gasses boiled off during its passage near the Sun) also play an important (but smaller) role in altering the orbit.

3. Physical Properties of a Comet • A comet is an icy body that releases gas or dust. • They are often called dirty snowballs, or snowy dirtballs. • Comets contain dust, ice, carbon dioxide, ammonia, methane and more. • Some researchers think comets might have originally brought some of the water and organic molecules to Earth. • Comets orbit the sun, but most are believed to inhabit in an area known as the Oort Cloud, far beyond the orbit of Pluto. • Occasionally a comet streaks through the inner solar system; some regularly, some only once every few centuries. • Many people have never seen a comet, but those who have won't easily forget the celestial show.

4. Comet that are icy black rocks or are covered in dust are far away from the Sun. • Sometimes this water, gas, rocks and dust can been seen from the Earth as one or two tails streaming away from the comet. • Even when only one tail can be seen, there are two; one made from the lighter gas and water, and the other from the rocks, dust and chunks of ice.