Every year on June 8, World Ocean Day celebrates the vitality and importance of the ocean, and how we can protect it. But our planet didn’t always have an ocean. Earth has been around for about 4.5 billion years, but there was no ocean in sight for the first billion or so. That’s in part because the planet was too hot for water to stick around in liquid form.
The planet eventually started to cool below the boiling point of water – 212 degrees Fahrenheit – allowing the early ocean to form around 3.8 billion years ago, according to the National Oceanic and Atmospheric Administration. At that time, water began to condense in the atmosphere and rain down in the basins on the Earth’s landscape, said Peter Adams, a geologist at the University of Florida.
There’s some debate around how water arrived on Earth in the first place. One theory is that volcanic eruptions expelled water vapor and other gases from the planet’s interior, and that water vapor condensed as the planet cooled. Another suggests that icy comets deposited water when they crashed into the early planet. The reality could be a combination of these theories, plus one other that involves the major collision event that is believed to have created the moon.
Regardless of the ultimate explanation, the Earth’s specific location in the solar system happens to be the perfect place for water to exist in all three phases — ice, liquid and water vapor, Adams noted. If the planet were any closer to the sun, it would be too hot for liquid water to stick around; if it were any farther, water vapor couldn’t exist.
“We’re in the Goldilocks zone because we can move water around the planet in all three forms, and because it can exist in all three forms, we’re in that sweet spot,” he said.
This video was produced by Bella Isaacs-Thomas, Megan McGrew, Jackie Hai, Julia Griffin and Molly Finnegan.
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