Title: How many planets in our universe could support life? | HowStuffWorks
Headings: How many planets in our universe could support life?
How many planets in our universe could support life?
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The requirements themselves are pretty straightforward. For one, we need liquid water. Water dissolves and transports chemicals, causing important metabolic reactions. We also need energy to create and sustain life, so light energy (from a warm sun and atmosphere) or chemical energy (from chemical reactions) needs to be present. Nutrients are required to build and maintain life. A planet with a water cycle, habitable atmosphere or volcanic activity can replenish and circulate nutrients [source: Lunar Planetary Institute ]. So it may seem like the chances are small that we'll find another planet that supports life in our universe. Those are pretty specific requirements, after all -- maybe there's one? Two?