Former General Science Teacher
The Earth is a special place. It has the rare conditions that make life possible. The Earth has liquid-water and its distance from the Sun make just right temperature on the Earth.
Does life exist only on Earth? Scientists would love to find evidence of life out in space. Scientists are expecting life in two candidates in solar system, the Mars and Europa (a moon of Jupiter). On the Mars’ surface, signs of the flow of water were found and the Europa has a warm interior and may have liquid-water beneath its icy surface. Living things change the land, sea and air. If life had not evolved on the Earth, there would be much less oxygen in our atmosphere and no fossils in the rocks. So the conditions on Mars and the Europa may give clues about the existence of life, there now or in the past. For that, scientists sent ‘The Path Finder’, the wheeled robot to the Mars, to find any form of life, even simple bacteria, but could not find any evidence of life on the Mars.
Scientists put forward SETI project (The Search for Extra Terrestrial Intelligence) to find the evidence of intelligent life in space. If we want to detect life far out in space, we have to hope that the life is intelligent and sending out signals. The search for this signal is called SETI project. In 1960 physicist Jocelyn Bell noticed strange signals coming from a distant star. May be the signals had been sent by distant aliens. If in any nearest star have an intelligent life, communication with them will be impossible. Radio waves take about four years to reach us from the nearest stars, and 2 million years from our nearest galaxy Andromeda. If we send signals now, it will be received only after 2 million years by the Andromeda. So astronauts are unlikely to visit planets where life exists.
Source: Arutha (60th Anniversary Magazine of Kumundhoo School, 2008)