AMBASSADORS

Our Wet Rock

Take a basketball and submerge it in a pool or tub of water.

When you pull it out, the water that sticks to the ball has the same thickness as the ocean is to the sphere of the Earth. We live on a wet rock. The ocean seems deep to us, but it is actually just a thin film of water clinging to the outside of large ball.

Even though we call them the seven seas, there is only one ocean. Like the petals of a rose that rise from the base of the flower, the circular Antarctic gives rise to the Atlantic, Indian and Pacific until they meet again in the Arctic.

Warm and cold currents circle the globe as slow motion liquid weather, fueling the climate and bringing nutrients to marine life. The ocean is almost as old as the Earth itself, having spewed out of the mouths of volcanoes and fallen from space as our planet was bombarded with icy comets and asteroids in it’s early history. The water we see today has been recycled over and over again for billions of years, so the molecules in that glass you are about to drink have likely been through a dinosaur.

Earth is the only planet we know of with liquid water on its surface, but it is not the only world with an ocean. Mars was once covered with lakes, rivers and seas about three billion years ago. Unfortunately, its volcanoes went quiet, much of the atmosphere was burned off by the sun, leaving the surface today a cold dry desert. Any water that remains has frozen in polar ice caps and underground permafrost.

Beyond Mars, several moons of the giant planets Jupiter and Saturn have liquid or slushy oceans under their icy surfaces. Europa, orbiting Jupiter, is believed to hold more water than all the ocean on Earth. A spacecraft called Europa Clipper is on its way to investigate this watery world to look for cracks in the ice and possible signs of life within.

Enceladus, circling the ringed planet Saturn, has large cracks near its south pole with ice geysers spewing out into space. The Cassini spacecraft flew through those plumes and detected not only water ice, but chemicals similar to those found around hydrothermal vents at the bottom of the ocean on Earth. Could there be vents in the ocean of Enceladus and could they be oasis of life as they are here?

Even distant Pluto, far out in the cold dark depths at the edge of the solar system is believed to have a liquid layer beneath its icy surface.

It looks like we need to send some Canadians to these remote moons and do a little ice fishing. Although they will need a good drill and long lines because these ice coverings are believed to be many kilometres thick.

The only alien world with liquid rivers and lakes is Titan, a giant moon of Saturn, larger than our moon and the only one with an atmosphere thicker than Earth’s. This bizarre moon has been referred to as the primitive Earth in deep freeze. At more than two hundred degrees below zero, water is frozen as hard as rock, forming the rugged ground. However, at those extremely low temperatures, methane turns into a liquid, raining down and filling lakes and rivers. Methane goes through the same cycle of evaporation, condensation and precipitation as water does on Earth. One of Titan’s methane lakes is the size of Lake Superior. Organic chemicals, similar to those found on Earth before life emerged are scattered across the surface of Titan. Will it too come alive in the distant future when the sun swells into a red giant star?

Astronomers have found roughly 6000 planets orbiting other stars in our galactic neighbourhood with the number still rising.

It seems like every one of the hundreds of billions of stars in our Milky Way has one or more planets. That’s a trillion planets in our galaxy alone.

Many of these exoplanets are in the goldilocks zone, where they are just the right distance from their star so they are not too hot and not too cold so liquid water could exist on their surfaces. So far, it has not been proven whether any of these planets are water worlds or if there is life in those distant oceans. But even if there is alien life somewhere out there, it will be very difficult to study and impossible to reach. It takes more than a human lifetime for our current spacecraft to cross interstellar distances.

So while the universe could be teeming with life, it is spread out over unimaginably vast distances. Perhaps one day, an advanced space-faring race will come to us, but in the meantime, Earth is the only planet we know of where water can exist in three states, solid liquid and gas, and the only planet we know that contains life. Our existence is completely dependent on this thin wet film that clings to our third rock from the sun.

We know we have changed our ocean, we also know we can protect it. Thankfully, the marine ecosystem is robust and capable of recovery if we leave it alone. So let’s do that. As you participate in Ocean Week Canada activities, think about extending them into Ocean Year, Ocean Decade or Ocean Century.

AMBASSADORS

Our Wet Rock

Bob McDonald

Take a basketball and submerge it in a pool or tub of water.

Astronomers have found roughly 6000 planets orbiting other stars in our galactic neighbourhood with the number still rising.

It’s the only one we have.