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Apr - May 98
Astronomical
Feature of the Month
COLD VOLCANOES
"Blues For Neptune" By Bob Eggleton A geyser shoots liquid nitrogen into the frozen atmosphere of Triton. Artwork available for purchase from Novagraphics.
Are all volcanoes hot? You would think they were - which is precisely why
members of the JPL team processing images from Voyager 2 were so astounded when they
discovered what looked like active volcanism on Neptune’s moon Triton. With a
surface temperature of -235 degrees Celsius, Triton was thought to be a cold, frozen,
inactive world. Far from it! Geysers blast plumes of liquid nitrogen 8,000 meters up
into the air, where wind patterns make long dark streaks on the surface out of debris
carried in the liquid. The exact mechanism causing these eruptions is unknown, but all it
would require is a little heat at the bottom of the ice cap. The warmth would evaporate
some of the frozen nitrogen trapped beneath the ice, making a pocket of gas. When the
pressure builds enough, gaseous and slushy nitrogen would burst through the ice as a
geyser. The heat could come from tidal stretching of the moon (like Jupiter’s Io) or
from a greenhouse-like buildup of warmth from the distant Sun by semi-transparent parts of
the ice cap. Whatever the cause, the effect is startling, totally unexpected, and
definitely a subject for an IAAA painting!
Oblique angle Voyager image of Triton geysers. Long curved line in center top is plume of "smoke." Short vertical line on left end of curve is 8000 meter tall jet of liquid.
International Association of Astronomical Artists