The search for life in space goes hand-and-hand with the search for water on planets around other stars. Water is one of the most common molecules in the universe, and all life on Earth requires it. Water functions as a solvent by dissolving substances and enabling key chemical reactions in animal, plant and microbial cells. It is much better at this than other liquids.

Astronomers are intrigued when finding evidence of water vapor on exoplanets. A recent target is the planet GJ 9827d, which may have a water-rich atmosphere around it. No bigger than twice Earth's diameter, the planet could be an example of potential water-rich worlds elsewhere in our galaxy. But don't plan on buying real estate on GJ 9827d. The planet is as hot as Venus, at 800 degrees Fahrenheit. This makes it a steamy world.