Buzz
What conditions are necessary for life? That depends on how you define "life."
Fuse/ThinkstockMain Points to Remember
- Common necessities for Earth-based life include being carbon-based, needing water, harnessing energy, and having the ability to grow or reproduce.
- Life requires water for numerous chemical reactions and energy sources like light or chemicals to fuel metabolic processes.
- An atmosphere that shields from harmful radiation and maintains warmth, along with nutrients replenished through planetary processes like volcanic eruptions, are essential for sustaining life as we know it on Earth.
Interestingly, there is no universal definition of life. We can't pinpoint life to a specific trait like breathing or growth, as living organisms are so diverse that it's impossible to define a single criterion.
We can discuss some common features that all living things on Earth share: They are carbon-based, they need water, they require energy, and most crucially, they have the ability to grow or reproduce in some form.
Is that all that scientists and astrobiologists are searching for when hunting for signs of life beyond Earth? Let's dive deeper into what conditions are truly necessary for life to exist.
As we mentioned earlier, one fundamental requirement is water, essential for many chemical processes [source: NASA]. Liquid water allows for chemicals to dissolve or be transported, so it must remain between 59 and 239 degrees Fahrenheit (15 and 115 degrees Celsius) to avoid vaporization or freezing [source: NASA].
Energy, whether from light or chemicals, is also necessary for life. Both forms power the metabolic processes that enable reproduction. In addition to energy, a planet must have an atmosphere that shields it from harmful solar radiation while maintaining warmth.
Naturally, life also needs nutrients to survive. The atmosphere of a planet or moon can even supply these. Methane, for example, can generate carbohydrates and fats, possibly contributing to my ideal-cheese-and-wine planet [source: NASA]. These systems must be able to replenish nutrients, which is easily done if the planet experiences phenomena like volcanic eruptions or weather systems that produce water.
Here's the twist: While scientists can fairly confidently suggest that these elements may be vital for life on Earth, it's important to remember that all of our assumptions are rooted in the context of Earth itself. We can't be certain whether other planets or moons might support a form of "life" that doesn't rely on the same conditions as those found in Earth-based ecosystems. For now, we'll focus our search on planets with the presence of nutrients, energy, and water.
