Water truly is a mysterious and wonderful substance! As a liquid, it nevertheless can change form, ranging from ice to steam. It is essential for life and commercial activity. Yet, when it floods, it can destroy life and commercial activity.
Part of water's mystery is its origin on earth, an issue that has challenged science for years. More recently, it has been assumed water was delivered to earth as ice by comets or asteroids.
However, according to Science News (January 15, 2011, p.26), there are two new theories as to how water originated on earth.
One new theory is that, at the time when the inner planets of the solar system were forming, Jupiter and Saturn moved around. They entered into the inner solar system and then backed out, kicking some ice bodies from the outer solar system into orbits which enabled the ice bodies to reach earth.
According to the article, a second new theory is that water came into being on earth from the cosmic dust from which the earth was formed. The dust grains held onto water molecules so tightly that high temperatures had no adverse impact.
Of course, there always has been a third explanation: that God created water on earth.
The Science News article points out that theories as to formation of water on earth may be helpful and encouraging for discovery of water in other locations in the universe.
Perhaps just as important, or even more so, is understanding that fresh water on earth, regardless of source, is a limited resource, a resource that must be understood, protected and conserved. We cannot expect bodies from outer space to deliver any more water to earth.