Mars has long been looked upon as a prime candidate
for extra-terrestrial life, and is the subject of many a wild science
Towards the end of the 18th century, the German born
astronomer William Herschel made many interesting comparisons of the Earth
and Mars, sparking off the idea of there being life on Mars. He worked
during the peak in early telescopic observations of the planets, and his
observations of Mars heralded the beginning of the search for extra terrestrial
intelligence. After all, where else should there be life other than on
a planet which shows so many remarkable similarities to our own? Herschel's
results were as follows:
- He determined the length of the Martian day as
24 hours, 39 minutes and 22 seconds, a mere 14 seconds below the currently
- He noted that the rotation axis of Mars is inclined
at an angle of 25° to the ecliptic, compared to Earth's 23.5°. Similarly
to Earth therefore, Herschel noted the changing seasons, although the
Martian equivalents are almost twice as long, because it takes almost
two Earth years for Mars to orbit the Sun. He even went as far as correctly
associating the seasons with the growth and shrinkage of the polar ice
caps (which he inferred were thin layers of ice and snow). In a Martian
hemisphere, spring and summer sees the polar cap shrink and the dark
surface features become more distinct. Conversely, in autumn and winter
the polar cap begins to grow and the dark features fade.
- He detected changes in the light and dark patterns
of the planet surface, which he associated with cloud cover and cloud
As a result of all of this data, by the end of the
18th century, Mars was seen as being very much like Earth in many respects.
Both have a day of approximately 24 hours, both show successive seasons
resulting in variations in polar ice cap sizes, and both have clouds obscuring
parts of the surface. The growing resemblance of Mars to Earth soon led
to the logical supposition that the dark features could be vegetation,
growing in spring and summer before receding in the autumn and winter.
This idea developed into the possibility of there also being intelligent
life on Mars and this theory became so strong that in 1802 the German
mathematician Karl Friedrich Gauss proposed that the Martians be signalled
by drawing huge geometric patterns in the Siberian snow! His suggestion
was never carried out.
The most famous observation that lead to the suggestion
of the presence of life on Mars must be that of `Martian canals'. It is
often put forward that the Italian astronomer Giovanni Schiaparelli first
noted these features during his mapping through the favourable opposition
in 1877. However, it was in fact Father Pietro Secchi who first observed
40 or so linear, straight line features criss-crossing the Martian surface
in 1869 which he termed canali, meaning `natural water channels'. This
term was soon mistranslated into English as canals and the idea arose
that an alien race was desperately constructing canals to store water
so as they could survive on their fast drying planet. This theory was
popularised by the wealthy American amateur Percival Lowell (1855 - 1906)
who financed the construction of a major new observatory near Flagstaff,
Arizona which would be used primarily for continuing studies of Mars.
By the end of the nineteenth century, Lowell had reported the observation
of 160 canals.
Despite the public excitement brewing at theories
of life on Mars at this time, many astronomers still could not accept
the features as being true canals. In 1894, the American astronomer Edward
`To save my soul I can't believe
in the canals as Schiaparelli draws them'
However, these more sceptical views were easily drowned
out by the exciting announcements of Lowell and his colleagues. it soon
became fashionable to view the Martians as a race who constructed massive
canals as irrigation networks, carrying water from the polar caps to vegetation
near the equators. The reddish appearance of Mars was suggestive of a
dying, desert-like planet whose occupants had to struggle to irrigate
their farmlands. The prospect of Martian invasions became the typical
plot for an explosion of science fiction novels, with the aliens abandoning
their arid homeland to invade the Earth for it's abundant resources.
The reason for such speculation stems from the fact
that superficially, Mars appears to have many Earth-like characteristics.
However, the barrage of spacecraft we have sent to Mars have shown us
a very different world indeed. Mars, as it is now, would prove to be very
hostile for the development and sustainment of life. However, in the past,
the planet was probably far more like the Earth and could well have hosted
all of the necessary conditions for life to begin. July 1996 saw excitement
of this prospect grow when NASA released the results of their study of
a Martian meteorite (called ALH84001) in which they claimed to have found
fossilised bacteria. Although this result is still in question, it has
raised the possibility of there once having been micro-organisms living
on or beneath the Martian surface. These are not quite the canal building
or spacecraft flying, bug-eyed aliens many were once expecting, but they
are still more than enough of a find to warrant a huge public interest
and a revival of spacecraft (and possibly even manned) missions to Mars.
Marvin the Martian image TM & ©
1998 Warner Bros.