Life on Other Planets.

One of the most common unanswered questions scientists find themselves asking is "Is there life on other planets?" Since the first famously documented UFO sighting in 1947, the idea of extra-terrestrial life has been debated almost non-stop. The subject has inspired many TV programs, such as The X-Files, and films (Mars Attacks, Independence Day, and the Men in Black films to name but a few). Scientists have come up with many new ideas and ways of trying to either prove or disprove the existence of life elsewhere.

Mars is a very similar planet to earth in relation to size and atmosphere. Therefore it seemed like the most likely place to search for life. At the end of the 19th century, an American named Percival Lowell built himself an observatory so that it was possible for him to study Mars in intimate detail when its orbit was closest to Earth. At this time it had recently been suggested that the planet had a system of channels on the surface, present from the evaporation of flowing water. Looking through his telescope Lowell became convinced he could see a network of artificial canals. This led him to believe that there were intelligent beings on Mars who had built these canals. However, spacecraft have now visited Mars and found that there is no evidence of water at all. It is now thought that the lines he could see were the combination of Lowell's overactive imagination, and scratches on the lens of his telescope. We are now searching one of Jupiter's moons, Europa, as this seems to be the next likely place to hold life.

It is seen to be more likely, however, that we will find less intelligent life in one of two different ways:

It may be possible for us to obtain material from another planet or moon or star from elsewhere in the Solar System. Spacecraft may be able to visit these bodies and, for example, use a robot to collect material for examination. This may be examined on site, or brought to Earth to be investigated in laboratory conditions. They could be tested for things such as evidence of fossilised organisms. Another, possibly slightly far-fetched hope is that we may find simple organisms like bacteria actually living on the desired planet. These ideas spanned from the discovery of rock on our planet that originated from Mars; knocked from the planet when a comet collided with it. In 1996 a group of scientists created conflict by claiming that they had found evidence of fossilised bacteria in one of these rocks, but other scientists disputed this idea.

The other possibility is that we can examine the atmosphere of other likely planets or moons. The planet Earth is largely made up of oxygen (20%) due to the presence of photosynthesising plants producing oxygen as a waste product. If an indication of oxygen appeared in a different planetary atmosphere, it would have a high chance of holding life forms on it. To learn about different atmospheres it isn't mandatory to visit the planet. We can find this information by looking at the light spectrum it emits.

People however think it would be more fascinating to discover intelligent life elsewhere. The Search for Extra-Terrestrial Intelligence project (SETI) has been running for several decades, but has not yet found any concrete evidence that intelligent beings truly exist outside of Earth.

Earth is constantly sending radiation into space. All broadcasting stations produce radio waves. These waves spread from a transmitter, and many of these end up in space, travelling away from us at the speed of light. It is very possible that, if there is intelligent life capable of producing these same signals, we will be able to pick them up. It is just as likely that they will deliberately send out signals that we will be able to receive, and will convince us of extra-terrestrial intelligence. The SETI project has been using radio telescopes since the 60's, but has had no positive results yet.

The SETI project began in 1959 when Philip Morrison and Giuseppe

Coconni publish in Nature magazine the first modern SETI article, "Searching for Interstellar Communication," which first illustrated the potential of using microwave radio for extraterrestrial communication. In 1960 Dr. Frank Drake conducted the first SETI search, Project Ozma. In 1961 the first SETI conference, Order of the Dolphin, is held at the National Radio Astronomy Observatory in Green Bank, WV. Dr. Drake introduces as its agenda what is now know as the Drake Equation, a controversial statistical method for estimating the number of advanced technological civilizations in the Milky Way Galaxy. In 1982 NASA began SETI searches with The High Resolution Microwave Survey (HRMS). 1988 saw The Planetary Society organize an international meeting on SETI in Toronto, Canada. This led to a Robert Stephens establishing project