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  • Jupiter.

  • Uranus.

  • Saturn.

  • Earth?

  • Sadly, the Earth didn't make it onto the list

  • of the Solar System's ringed planets.

  • This is WHAT IF,

  • and here's what would happen

  • if the Earth had rings like Saturn.

  • When the Earth was young,

  • it most likely had a ring of rock debris around it.

  • 4.5 billion years ago another planet, Theia, hit the Earth.

  • The giant impact sent a ring of matter

  • hurtling into the Earth's orbit.

  • But it didn't stay like that for long.

  • The rocky debris soon formed another celestial body -

  • the one we now call the Moon.

  • Having planetary rings visible in the sky

  • would look way more spectacular than just one grey rock, right?

  • Maybe.

  • But if our planet got beautiful rings like these tomorrow,

  • much of life on Earth might not survive the renovation process.

  • It wouldn't necessarily take another collision

  • to form rings around the Earth.

  • We could just crumble the Moon.

  • And for that, we'd only need to move it a little closer.

  • The gravitational pull that our planet exerts on the Moon

  • isn't equal everywhere.

  • It's much stronger on the side of the Moon that is closest to us.

  • There is a limit on how close celestial bodies can be to each other.

  • It's called the Roche limit.

  • If they get any closer than that limit,

  • the larger body shreds the smaller one into pieces.

  • The distance of the Roche Limit depends on the size,

  • mass and density of the two objects.

  • For instance, the Sun rips up comets that comets

  • within 1.3 million km (0.8 million mi) of it.

  • The Earth will tear apart an average-sized comet

  • from approximately 18,000 km (11,185 mi) away.

  • For the Moon, the Roche limit would be 9,500 km (5,900 mi).

  • The rings we might get from something the size of the Moon

  • would be about 5,000 km (3,100 mi) wide

  • and around 9.5 m (31 ft) thick.

  • But unlike Saturn's icy rings,

  • ours would be made of nothing but rock.

  • The Earth is just too close to the Sun to keep the debris iced.

  • Looking out at the sky,

  • you'd be able to see these rings from Earth at all times.

  • Because of the brightness of the rings,

  • the Moon wouldn't seem as bright anymore.

  • That is if we still had the Moon.

  • If the Moon crumbled up and became our rings,

  • there'd be nothing else up there to look at.

  • And there would be some other consequences.

  • The rings suddenly hugging Earth

  • would disrupt internal navigation systems of some animals.

  • If not enough direct sunlight was making it through the rings,

  • they would also affect photosynthesis

  • and our oxygen supply.

  • In the shadow of the rings, with no contact from the Sun's rays,

  • the temperature would get so cold

  • that it would make the shadowed areas of the Earth almost uninhabitable.

  • Communications satellites, generally placed around the Earth's equator,

  • would find themselves right in the middle of a rock storm.

  • We'd need to find another way to keep the internet alive

  • if we want to keep posting selfies on a ringed Earth.

  • We'd be better off in a scenario

  • where the Earth has always been like this.

  • Provided we didn't lose sunlight and oxygen,

  • we'd evolve just fine.

  • But we'd have to develop other means of communication

  • since we wouldn't be able to send satellites into an orbit full of rocks.

  • Space would never become our final frontier.

  • The rocky rings around the planet

  • would be a sort of orbital barbed wire fence

  • keeping us all grounded.

  • And, just like the rings of Saturn,

  • Earth's rings wouldn't last forever.

  • One day they'd start to feel their age and drop from the sky.

  • Make sure to wear a helmet,

  • and don't forget to look up and enjoy the show.

  • If the multiverse is real,

  • there might be a ringed Earth somewhere out there,

  • with people on it wondering

  • what it would be like to live on a planet with no rings.

  • But we'll leave that story for another WHAT IF.

Jupiter.

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如果地球有土星那樣的環呢? (What if Earth Had Rings Like Saturn?)

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    林宜悉 發佈於 2021 年 01 月 14 日
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