Where Did Earth's Water Come From?

In the early 1900’s, within a massive observatory hidden amidst the forests of Flagstaff, Arizona, astronomer Percival Lowell made a startling discovery. Peering through his imposing telescope, he claimed to have witness characteristics of Mars which had never been seen before, including evidence of reflective waters, crisscrossing canals and patches of vegetation. The scientific community was skeptical, but it would be another 70 years before his observations could be confirmed or disproven. Lowell's discoveries might have been far-fetched, but they could not be dismissed entirely.

This is the prelude to Where Did Earth's Water Come From?, and it quickly establishes space exploration as a constantly evolving endeavor, revealing deeper layers of understanding with each passing generation. The same dynamic applies to our own planet.

Mars is thought to have once housed water and possibly the means for sustaining life, but that was billions of years ago. How did Earth and Mars experience such a vastly different fate?

Water defines the longevity and vitality of our planet, but how it arrived and endured remains a bit of a mystery. The film looks upon the most progressive research to posit a theory: a series of icy asteroids once struck our planet, and their liquid contents informed the formation of our oceans. These asteroids were set on their course thanks to the gravitational tugs and pulls of the planet Jupiter.

The investigation into the extraterrestrial origins of our water includes studies of the Earth’s crust, the composition of asteroids, the nature of moisture in our atmosphere, and the various events from the distant past which conspired to create our wholly unique planet.

Can we retrace the four-billion year history of Earth's climate? Through every age, no matter how inhospitable, water has remained. The filmmaker outlines the roles that the Sun, volcanoes and the Earth's magnetic fields might have played in making that possible.

The film may be brief in running time, but it's ambitious in scope. Our interconnected universe houses a history of mammoth scope and scale, and the film does a noble job of exploring the possibilities from one slice of that history.