1. By: Juan Alvarado and Cameron Murry

2.  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.  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.