in our Solar System
surface of Mars as seen from a Viking lander (NASA)
Of the nine planets in our Solar System only two
seem good candidates for life as we know it. The planet closest
to the Sun, Mercury, is too hot. The next out, Venus, while
it is very Earth-like in size and shape, has an average temperature
of 475 degrees C (still too hot), and a lack of life giving
Earth, of course, shows some signs of intelligent
life. Mars, which we'll come back to in a moment, is the next.
Beyond that the planets, with the exception of the last, Pluto,
are gas giants (Jupiter, Saturn, Uranus and Neptune) who's high
pressure atmosphere's and chill temperatures, though they don't
rule out life, suggest it would be in a form much different
than our own.
Planet Mars (NASA,
Calvin J. Hamliton)
When large telescopes were first built a century
ago, astronomers turned their attention towards Mars. Giovanni
Schiaparelli, an Italian, published a series of observations
he'd made of Mars including reports of canali (Italian for channels)
he'd seen on the surface. When the word was improperly translated
to English as "canals" it seemed to connote they were dug by
intelligent life. Later on Percival Lowell, who studied Mars
for decades from his observatory in Flagstaff, Arizona, furthered
this idea of canals and suggested that they were dug by intelligent
beings. Others even suggested that the Martian
moons were really artificial satellites.
More careful observations in this century show
that the "canals" once seen do not seem to match surface features
actually on Mars. The best explanation for the earlier observations
are wind storms that cover and uncover darker rock of the surface
with lighter colored sand.
"Face" formation on Mars (NASA,
Calvin J. Hamliton)
Close observations of Mars via probes (including
landers on the surface) have failed to find any trace of intelligent
life or it's remains. (Strangely enough the best evidence for
life on Mars was discovered back
on Earth) But robot observers and landers have found the marks
of dry stream beds indicating that water, a requirement for
all Earth life, once flowed on the surface. Now the planet seems
dry. Martian temperatures can get as warm as 70 degree Fahrenheit
under the best conditions, but usually stay below freezing.
The air is thin and unbreathable by our standards. These factors
do not completely rule out life and the Viking 1 and 2 landers
attempted to sample the soil to look for signs of organic activity.
Most of the tests came back negative and the single positive
test may be the result of an unusual chemical reaction taking
place in the soil. Again the tests do not completely rule out
primitive life on Mars as only a small portion of the surface
Photographs of the terrain of Mars did uncover
an unusual feature: a cluster of hills that, when seen with
the Sun at a particular angle, resembles a face. Nearby are
other features that look like pyramids. Some have interpreted
these as sculptures by Martians similar to the giant figures
etched in the ground on Earth in such places as Nazca,
Peru. It is much more likely, though, they are a fully natural
phenomenon not unlike shapes or faces often seen, by imaginative
humans, on Earth in mountains or hills.
(NASA, Calvin J.
There is also one surprise candidate for life
in our solar system. Far out beyond the orbit of Mars lies the
largest planet in our solar system, the gas giant, Jupiter.
One of it's fourteen plus moons, Europa, seems to be covered
with smooth, but cracked ice. Scientists have suggested that
the tidal forces on Europa (caused by the pull of Jupiter's
gravity and the motion of the moon's orbit) may give this Europa
a hot core. If that is true there may be liquid water below
Europa's ice shell. Hot volcanic vents on this ocean floor might
be an environment that would enable life forms similar to the
creatures that populate thermal vents in Earth's oceans to survive.
It seems unlikely though, if these creatures exist, that they
are operating flying saucers.
Copyright Lee Krystek 1996.
All Rights Reserved.