Comets
Comets...Dirty Ball of Ice
• They look like a star with a ghostly white tail.
• The term comet derived from the Greek word
“aster kometes”, which means long-haired star.
• Composed of ice, frozen gases (ammonia, methane, Carbon dioxide, and other organic compounds.
Comets…where they come from?
Kuiper Belt -
Similar to asteroid but found beyond Neptune.
Oort Cloud – Discovered in 1950 by Jan Oort, found beyond Pluto.
Movement of Comets
•
The red circle represents the orbit of one planet.
Although the comet in the animation is orbiting (blue) the Sun in a counter clockwise direction, there are many comets that orbit in the opposite direction.
As can be seen from the diagram, the tail of the comet always point away from the Sun, so after a comet has passed the Sun it actually travels tail first.
Movement of Comets
• They travel around the sun in long looping orbits that bring them near the sun on one end and around Jupiter on the other hand.
• If a comet has large orbit, it takes a long time to go around the sun. Some are
“short-period” comets that take 5 or 10 years to complete an orbit. Some are
“long-period” comets that take decades, centuries, or millennia to orbit the sun.
Movement of Comets…example
Comets… insights
• The comet’s tail is made of material from the comet; gas from the ices and dust that is mixed in with the ice. They escapes as the comets melts.
• The tail always points away from the sun due to the solar winds (movements of heat away from the sun.)
• They can be seen by us only when they pass by the sun and the sun’s heat melt them. Comets seen in the sky
Comets seen in the sky