1.  Water is an exception since the density of ice is lower than that of liquid water.

2.  And if liquid water once existed on Venus and Mars, then it may have nourished primitive life forms that have since gone extinct.

3.  And where there has been liquid water, scientists say, there could have been life.

4.  And where there is heat and liquid water, scientists point out, life in some form might thrive.

5.  Are you based on carbon and liquid water?

6.  As on Earth, liquid water on Europa would be a basic building block for life.

7.  As the temperature drops, liquid water refreezes as permafrost, once again transforming the planet into a cold, dry realm.

8.  At least one of them, astronomers say, could have liquid water, essential to life as it is known on Earth and presumably elsewhere.

9.  Although comets have been more feared than admired, they may well have provided the liquid water and organic molecules from which life on Earth has evolved.

10.  But between the two extremes is liquid water, which can move in complex patterns that are almost mesmerizing.