 Back |
Next
|
Comets
-
Where
do comets come from?
-
Oort
cloud or Kuiper Belt
-
Are
comets young or old?
-
Very
old
-
Probably
left-over icy planetesimals
-
Comets
are mostly ice
-
What
happens to ice when it is far from the sun?
-
When
ice gets close to the sun it vaporizes
-
Water
vapor (H2O) is broken up by sunlight into oxygen and hydrogen
-
Sunlight
does not push on hydrogen, expands in a ball 10 million km wide
-
is
this what we think of when we see a comet?
-
other
effects give the interesting shapes, colors
-
Does
a comet die when it comes close to the sun?
-
Usually
not: it looses 0.5% to 1% of its mass per orbit
-
Death
sequence described later
Comet
Kohoutek, 1974. Optical light (left) hydrogen UV lines only (right)
| Back |
Next
|