Transcript Other Celestial Objects - science9atsouthcarletonhs

Other Celestial
Objects
Comets, asteroids,
meteoroids, meteors, and
meteorites
Comet
 A comet is sometimes
called a “dirty snowball”.
 It is a mixture of frozen
water, gases and dust.
 A comet is invisible
except when it is near
the Sun.
 A comet has a very
eccentric orbit.
A comet’s tail
 As it approaches the Sun, a
tail, millions of km long
becomes visible.
 A comet’s tail will always
face away from the Sun as it
is created by the solar wind
from the Sun.
 http://www.windows.ucar.edu
/tour/link=/comets/comet_mo
del_interactive.html
 http://www.esa.int/SPECIAL
S/Rosetta/SEM3NV0PGQD_
0.html
asteroids
 Most asteroids are
found in the asteroid
belt, between Mars and
Jupiter.
 They have a rocky
composition.
 The largest asteroid
known is Ceres
Meteoroid
 A meteroid is a rock travelling through space but has
yet to reach the Earth’s atmosphere.
meteors
 A meteor is a bright streak of light in the sky (a
shooting star or a falling star) produced when a small
meteroroid enters the Earth’s atmosphere.
 Most meteoroids are small and burn up due to the
heat of friction through the atmosphere.
A Meteor’s orbit
 If you have a dark clear sky ,on an average night, you
will probably see a few meteors per hour.
 During one of the annual meteor showers you may
see as many as 100/hour.
meteorites
 Only the largest meteors can survive travelling
through Earth’s atmosphere and fall to Earth as
meteorites.
A Famous Meteorite
 The Hoba meteorite is
the largest meteorite to
be discovered. It was
found in Namibia, Africa
 This meteorite weighs
60 tons.
Meteorite craters
 Only meteoroids larger than
a few hundred tons can
survive and hit Earth, leaving
a crater.
 This crater is the Barringer
Crater, near
Winslow,Arizona. It was
formed 50,000 years ago by
an iron meteor about 30-50
m in diameter.
 The crater is 1200 m in
diameter and 200 m deep.
 About 120 impact craters
have been identified on the
Earth.