COMETS
Comets contain a nucleus, dust tail and an ion tail A comet is a small body of ice, rock, and cosmic dust loosely packed together Comets contain a nucleus, dust tail and an ion tail
COMETS Referred to as DIRTY SNOWBALLS due to their composition Probably left over from the time when the planets formed
COMETS
dust tail and an ion tail Center is the nucleus COMETS Passes close to the sun, solar radiation heats the comet and gas and dust stream off in the form of a LONG TAIL TWO TYPES OF TAILS dust tail and an ion tail Center is the nucleus
COMETS Elongated orbits Ion tail always POINTS AWAY from the sun – ion tail is blown away by solar wind (made of ions) Dust tails don’t always point away from the sun
COMETS Scientists think that comets come from: Oort Cloud, spherical region that surrounds the solar system When gravity of a passing planet/star disturbs part of the cloud, comets can be pulled toward the sun. Kuiper belt, which is the region outside the orbit of Neptune.
ASTEROIDS
ASTEROIDS Small, rocky bodies that revolve around the sun Irregular shapes Orbit in the ASTEROID BELT – wide region between the orbits of Mars and Jupiter Thought to be material left over from the formation of the solar system
Asteroid Belt
Types of Asteroids Outermost region of asteroid belt - asteroids are dark reddish brown (may be rich in organic material) Asteroids – dark gray surfaces – rich in carbon Inner most region – asteroids are light gray (stony or metallic composition) Examples: Hektor, Ceres, Vesta
Examples of Asteroids
METEOROIDS Meteoroid - A small, rocky body that revolves around the sun – probably pieces of asteroids Meteorite – meteoroid that enters earth’s atmosphere and strikes the ground Meteor – bright streak of light caused by a meteoroid/comet dust burning up in the atmosphere
Meteor
Meteors Meteor Shower- happen when Earth passes through the dusty debris that comets leave behind
Types of Meteorites
IMPACT CRATERS
IMPACT CRATERS When an object in space collides with another object in space – impact crater Planets/moons with no atmospheres have MORE IMPACT CRATERS Atmosphere acts as a shield – smaller objects “burn up”
Impact Craters Every few thousand years impacts may be powerful enough to cause a natural disaster Impact that is large enough to cause a global catastrophe are estimated to happen once every few hundred thousand years, on average
TORINO SCALE System that allows scientists to rate the hazard level of an object moving toward Earth 0 = small chance of hitting Earth 10 = definitely will hit Earth