The oldest continents in our galaxy may have arisen 5 billion years before Earth’s, new research suggests — and that means there may be multiple worlds in the Milky Way harboring alien life even more advanced than our own.

Astrobiologists think a planet needs to have certain features to support life: oxygen in its atmosphere, something to shield organisms from dangerous radiation and liquid water, for a start. Although big land masses aren't strictly necessary for living things to emerge, Earth's history shows that they're important for life to thrive and exist for long periods of time. So, if an exoplanet had continents before Earth, it follows that there might be older, more advanced life on that world.

This line of thought led Jane Greaves, an astronomer at Cardiff University astronomer in the U.K., to answer the question: When did the first continents appear on a planet in our galaxy? Turns out, two exoplanets' continents — and perhaps life — may have arisen four to five billion years before Earth's.

If life on another planet had a five-billion-year head start, it "could potentially host life more evolved than us," Greaves wrote in a study, published in the September issue of the journal Research Notes of the American Astronomical Society.

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[–] [email protected] 4 points 1 year ago* (last edited 1 year ago) (1 children)

I know what a continent means on a planet.
But what does it mean when talking about space or galaxies? Is it a specific area in space or a specific amount of area (wherever) in space?

So, if an exoplanet had continents before Earth -

I don't understand what this means 😅

[–] [email protected] 6 points 1 year ago* (last edited 1 year ago)

The wording was bad, for sure. It's referring to other planets that have large bodies of land that may be surrounded by a liquid. (Do continents have to be surrounded by water or other liquid? I am too lazy to find the exact definition. It was critical in our development, for sure.)

One possible translation: If continents formed on other planets, there is potential for those planets to form similar ecosystems. Tectonic activity also suggests a planet that has a hot interior and a stable magnetic field. Since the surface of the planet is active, heavier minerals could be pushed up instead of sinking down. This could help drive more complex chemical reactions.

Continents may imply complex shorelines as well. Much of the evolution on earth was driven by the need for plants and fungi to have access to vast quantities of water, ample sunlight and a better supply of fresh air. Shorelines have everything, including places for big critters to find and eat little critters.

Continents provide diverse conditions, for sure. If they existed on other earth-like planets before ours, it could have possibly given life a huge headstart.