Transcript Comets, Asteroids, and Meteoroids Power Point

COMETS
COMETS
• 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
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
Showerhappen 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