Hey Space Placers!
I was at work yesterday and the subject of other life in the Universe made the rounds. To a person (there were 5) each thought that life other than us and our planet existed elsewhere in the Universe.
I watched "Earth vs the Flying Saucers" last night and got the January 2012 issue of Sky and Telescope Magazine with the cover story "How Could Aliens Find Us?". To top it off, there is now a project being proposed to look for alien artifacts/evidence in the high-resolution photographs from Lunar Reconnaissance Orbiter (LRO) - http://www.sciencedirect.com/science/article/pii/S0094576511003249.
I will state my own view on the subject of extraterrestrial life - I believe that other life DOES exist in the Universe, if not our own solar system. To create life - as we know it - you need a stable and long term energy supply, a suitable habitat (water, atmosphere, chemical compounds, food sources) and sufficient time for evolutionary processes to work. To get where we are now, we have had the Sun, Earth, and 4.5 billion years going for us to create us and our planet teeming with life.
I truly believe that life can exist on Mars below the surface - not "Martians" as in War of the Worlds", but rather extremophile life forms like we find in the harshest habitats on our planet - deserts of ice and sand, the bottom of oceans, arid and acrid environments. And who knows what might lurk in the subsurface ocean of Europa.
There might come a time when discovery of life elsewhere is announced. As Carl Sagan once said, "Extraordinary claims require extraordinary proof". The Search for Extraterrestrial Intelligence (SETI) is ongoing in its listening to space in order to find possible signs of intelligent life - http://www.seti.org/ Curiosity is headed towards Mars with the most advance instruments available to study the Red Planet. NASA is looking at ways to study Europa's ocean. In sum, we are looking for signs of life and life itself elsewhere.
Do I believe that Earth has been or is being visited by aliens? I say that anything is possible but I stand by Dr. Sagan's axiom. It has to be proven by scientific means in order to be valid. Nothing else will do as anyone can say anything and "photograph" anything.
With 2012 literally around the corner the doomsday contingent may arise again - remember the movie and the "end of the Mayan Calendar means the end of the world" nonsense? I am pretty sure the planet will be here by the end of 2012 and hopefully humanity along with it.
Have you explored your own feelings on this subject? It is pretty hard to look up at a clear and totally dark sky with thousands of stars and the Milky Way and not think "we are not alone". And when you consider that there are BILLIONS of other galaxies, it becomes an almost certainty because of the sheer numbers of stars and planets out there that something/someone else must be looking back and pondering the same thoughts as they look into their sky.
Perhaps time will eventually tell us the answer to our question.
Sky Guy in VA