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?
Citation

Content: The only problem is that the Drake equation doesn't give us an answer; it just tells us what might be possible if we get the factors right. ( Which we won't, because they're all hypothetical.) And while it would be fun to imagine that we could find a planet populated with people made of putty instead of carbon, it's probably unlikely. Instead, we have to define the parameters of life on Earth and see which other planets fit the bill. Advertisement
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.