Many novels focusing on life on other planets written close to 1900 echo scientific ideas of the time, including Pierre-Simon Laplace's nebular hypothesis, Charles Darwin's theory of natural selection, and Gustav Kirchhoff's theory of spectroscopy.
These scientific ideas combined to present the possibility that planets are alike in composition and conditions for the development of species, which would likely lead to the emergence of life at a suitable geological age in a planet's development.

By the time Wells wrote The War of the Worlds, there had been three centuries of observation of Mars through telescopes.
Galileo observed the planet's phases in 1610 and in 1666 Giovanni Cassini identified the polar ice caps.
In 1878 Italian astronomer Giovanni Schiaparelli observed geological features which he called canali (Italian for "channels").
This was mistranslated into English as "canals" which, being artificial watercourses, fuelled the belief in intelligent extraterrestrial life on the planet.
This further influenced American astronomer Percival Lowell.

In 1895 Lowell published a book titled Mars, which speculated about an arid, dying landscape, whose inhabitants built canals to bring water from the polar caps to irrigate the remaining arable land.
This formed the most advanced scientific ideas about the conditions on the red planet available to Wells at the time The War of the Worlds was written, but the concept was later proved erroneous by more accurate observation of the planet, and later landings by Russian and American probes such as the two Viking missions, that found a lifeless world too cold for water to exist in its liquid state.
Many novels focusing on life on other planets written close to 1900 echo scientific ideas of the time, including Pierre-Simon Laplace's nebular hypothesis, Charles Darwin's theory of natural selection, and Gustav Kirchhoff's theory of spectroscopy. These scientific ideas combined to present the possibility that planets are alike in composition and conditions for the development of species, which would likely lead to the emergence of life at a suitable geological age in a planet's development.
By the time Wells wrote The War of the Worlds, there had been three centuries of observation of Mars through telescopes. Galileo observed the planet's phases in 1610 and in 1666 Giovanni Cassini identified the polar ice caps. In 1878 Italian astronomer Giovanni Schiaparelli observed geological features which he called canali (Italian for "channels"). This was mistranslated into English as "canals" which, being artificial watercourses, fuelled the belief in intelligent extraterrestrial life on the planet. This further influenced American astronomer Percival Lowell.
In 1895 Lowell published a book titled Mars, which speculated about an arid, dying landscape, whose inhabitants built canals to bring water from the polar caps to irrigate the remaining arable land. This formed the most advanced scientific ideas about the conditions on the red planet available to Wells at the time The War of the Worlds was written, but the concept was later proved erroneous by more accurate observation of the planet, and later landings by Russian and American probes such as the two Viking missions, that found a lifeless world too cold for water to exist in its liquid state.
The War of the Worlds