Is there life in the universe beyond our planet Earth? This is a question that has been pondered for literally thousand of years. Though scientists have yet to find proof of extraterrestrial life, they have discovered enough about biology and chemistry, along with the makeup of stars and other worlds, to formulate some comprehensive ideas about what kind of life and where such organisms might exist elsewhere in the cosmos.
A number of these ideas were presented at a recent lecture on the subject given at Fuertes Observatory at Cornell University. The lecture is part of a series given each semester by the Cornell Astronomical Society, or CAS, in conjunction with its open house program held every clear Friday evening at the observatory.
CAS member Bernadette Pang talked to an eager audience on "Astrobiology: The Study of Life, the Universe (if not quite Everything)." Defining astrobiology as "the study of life as it arose on Earth [and] as how it may arise elsewhere in the universe," Pang also explained what life is as we understand it: something that consumes food, grows, adapts to its environment, responds to stimuli and reproduces.
The Cornell biology and psychology student detailed how an organism might go about getting the energy it needs to sustain itself from various environments on both this world and others.
On Earth, life forms have a wide variety of energy sources to choose from, such as the sunlight plants use in photosynthesis. For creatures dwelling in places and on worlds with much harsher environments, their sources of food are often quite different from what most Earth organisms utilize.
Deep below the surface of our planet's oceans, beings exist in an environment that generally consists of constant darkness, immense pressures, and bitter cold from the surrounding water. However, a number of species are able to live and thrive in these conditions thanks to the geothermal vents that pepper the ocean floor.
Despite temperatures reaching over 1000º F, sulfur-eating bacteria, giant tube worms, clams and mussels live around these amazing expulsions from deep within our planet by converting energy from chemical reactions from the vents, a process known as chemosynthesis.
Scientists speculate that worlds such as Europa, a large moon of the planet Jupiter that might have a global ocean of liquid water under its thick ice crust, may also have geothermal vents that could support its own varieties of aquatic creatures.
As for the types of life that may exist in the universe, while there may certainly be some very exotic creatures composed of what we would consider to be rather bizarre molecular combinations, Pang showed how and why the makeup of virtually every organism on Earth might be the standard for most other life throughout space.
The primary element for life on this planet is carbon. This atom combines easily with other elements to make complex molecules and is quite abundant throughout the universe. Water is another fundamental ingredient for life on Earth. This combination of hydrogen and oxygen has as one major selling point its ability to remain liquid across a broad range of temperatures; it's an ideal medium for life to dwell in.
For worlds such as Saturn's giant satellite Titan, with its nitrogen and methane atmosphere and liquid hydrocarbon lakes wrapped in temperatures nearly -300º F, Pang noted that any life on that alien moon would have to possess a much different biochemical system from ours.
For more information on CAS, its lecture series and open house nights, visit www.astro.cornell.edu/cas.