There is no greater feeling in the world than the joy that overcomes me when I look up at the night sky and realize that somewhere up there, someone just like me might be looking back. Each of us wondering about the other's existence, each of us just as curious about the cosmos's wonders, and each of us separated by a seemingly endless void that may never -or at least not within our lifetimes- be transversed. However to me that doesn't spoil the wonder, it doesn't “dullen the thought”, in fact, it gives me a reason to protect this world, to cherish it, so that one day perhaps our descendants can make that voyage. One which we ourselves have laid the foundation.
When we look up at the night sky ..given adequate conditions of course.. we see a tapestry of stars displayed like christmas lights against the black curtain that is the cosmic void. This sight is truly awesome, it is humanly impossible to successfully count out each star displayed on an favorable night. Amongst this tapestry you may spot an orangish band stretching from horizon to horizon, this is the Milky Way, the center of our galaxy, it consists of billions upon billions of stars, nebulae, and other foreign bodies, it has dazzled us for generations. Surely somewhere amongst this vastness life has come about to intelligence, perhaps it has occurred many times. But it is important to note that even given the enormous amount of opportunities for life to arise elsewhere we are still separated a great many billion miles from even the nearest star system.
Given this fact even if life glitters the galaxy, civilizations may be completely helpless when it comes to making contact with one another. As professor Carl Sagan put it: We are but a mote of dust suspended in a sunbeam. We are one of many planets in just one of the many billions of star systems that make up the Milky Way galaxy.
Now, I find it very hard to believe that no where in the universe has a species developed the technological ability to pursue interstellar space, however, it is a different claim entirely to say that we have been visited by and even experimented on by a species that for whatever reason found us of any particular interest.
Regardless, there are many people who DO believe this claim and there are even some who say that they themselves have made contact with these cosmic voyagers.
While it seems unlikely that we'll come across any intelligent life in our current sphere of exploration.. It isn't unlikely to suspect that we'll come across much simpler organisms such as single celled bacterias or organisms like the water bear, an unbelievably durable organism known to survive even in the vacuum of space. Despite much of the known universe being an extreme hazard to life, there are some places within our own solar system that look promising to astronomers. Usually when talking about extraterrestrial life within our solar system there is one name that will inevitably be mentioned, Mars.
For many years people believed Mars to be inhabited by an Intelligent, globalized civilization. The reason for this was because when they looked up at Mars they could see deep trenches and marks scarred across the planet's surface. They believed these trenches were channels that transported water from the planet's ice caps to cities abroad the red planet. Of course upon further examination we came to realize that the red planet is nothing more than a cold, barren desert with no signs of life to be found.
Despite much speculation, and urban rumor, only recent discoveries from the Phoenix Rover indicate that Mars does in fact have water in its ice caps, and as we know water is one of the main components for life. This also helps back up years of the observational speculation that Mars at one point was much more like Earth, with flowing streams and lakes and perhaps even a thick atmosphere. So perhaps we shouldn't laugh to harshly at our predecessors, they were at least..partially right. However, for some mysterious reason Mars dried out, its atmosphere dissipated, and its lake beds dried up. A common theory is that Mars lost its atmosphere due to a phenomena known as sputtering, where radiation from the sun made isotopes in the Martian atmosphere making it slowly, but ever increasingly unstable, eventually turning Mars into the cold, dead world it is today. Now, it is suspected that some micro-organisms may have been able to survive under the red martian crust in small underwater streams. One reason to suspect this is because Mars has an unusually large amount of methane gas in its atmosphere, methane is one of the main products produced by organisms digestive waste or poop. But, even if we DID find fossils or even living micro-organisms under mars's crust, I don't suspect that we'd have very much to say to one another, I mean, I personally haven't had to interesting conversations with any Zygotes recently.
If we want to find more elaborate and complex forms of life, there is perhaps no better candidate than Jupiter's moon Europa. Europa is a small, icy world scarred with cracks and cavities caused by the gravity of Jupiter. At first glance Europa might seem like a cold, barren, ice sheet. However, astronomers aren't concerned with what's on Europa's scarred surface, but rather on what might be lying beneath it. Just as when I squeeze and compress this ball of clay, It is supposed that Jupiter's gravity might have compressed and stretched Europa enough to create an internal heat source within the tiny moon, melting away the lower layers, creating an ocean of liquid water under the moon's icy crust. I wonder what we'll discover should we decide to send an unmanned craft to the moon that would drill through the icy crust and expose the world below. Organisms like the jelly fish or squid come to mind when thinking about Europa's ocean's, they'd produce their own light and would more than likely rely on the heat streaming out of underwater volcanic jets. But until we actually crack Europa's surface, all we can do is speculate. Just like Venus and Mars, Europa may just be another barren lifeless rock drifting through space, waiting for the day when foreign explorers will make its secrets known.