Cutaway Callisto: Ice, Rock, and Ocean
Explanation:
Cruising past the moons of reigning gas giant Jupiter,
Voyager and
Galileo have returned tantalizing evidence for a
liquid water ocean
beneath the surface of Europa.
Now researchers are reporting telltale indications that the
battered Jovian moon Callisto may also harbor
a subsurface ocean.
This cutaway view of Callisto shows
a whitish 200 kilometer thick band of
ice just beneath the moon's surface.
The hypothetical ocean - indicated by the underlying light blue stripe -
is potentially a salty layer of liquid water up to 10 kilometers thick,
while the rest of the interior is seen as a jumble of rock and ice.
Why a salty subsurface ocean?
Magnetic measurements made during Galileo flybys so far indicate
Callisto's magnetic field is variable, analogous to
results during Europa passes, and a plausible explanation
is that Callisto too has a subsurface liquid layer.
If the liquid were salt water it could easily carry
electrical currents
and produce the
changing magnetic field.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
