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  • supporting this episode of SciShow.

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  • and learn some critical STEM skills!

  • [♪ INTRO]

  • We owe a lot to the Moon.

  • Without it, our tides wouldn't be as high,

  • our seasons wouldn't be as regular,

  • and our days would be much shorter.

  • But you know what? What we callthe Moon

  • isn't the only moon the Earth has ever had.

  • Once in a while, our planet's gravity

  • captures a tiny, rocky body, forcing it to

  • make a few orbits around us before it

  • continues its jaunt around the Sun.

  • Because they're so small, these objects

  • usually go undetected.

  • But what if Earth managed to capture something

  • a lot bigger?

  • Something much closer in mass

  • to our current Moon?

  • It might sound like a lot of fun, but once you

  • look at the consequences,

  • you might start to hope this never happens.

  • Now, not all of the consequences would be catastrophic.

  • For instance, if this second moon orbited close to Earth,

  • we would generally have more moonlight.

  • And while that would affect nocturnal animals

  • and make it easier for some predators to hunt,

  • it likely wouldn't destroy the food web.

  • The light probably isn't the thing

  • we'd be most concerned about, though.

  • We'd likely be thinking more about stuff like tides.

  • If we picked up another moon, its gravity

  • would cause Earth's tides to reach both

  • higher highs and lower lows over

  • the course of a month.

  • That means a lot of people would probably

  • have to move away from coastal areas,

  • shifting the population of our planet.

  • If the moons were orbiting at different distances

  • from Earth, they'd also be traveling at different speeds.

  • And that would further mess up our tidal system,

  • where we currently have a nice,

  • regular spacing between high and low tides.

  • The time between those tides would speed up,

  • causing more shoreline erosion.

  • And that would threaten not just aquatic life,

  • but human infrastructure, which would get

  • pummeled by waves all the more often.

  • This extra force wouldn't just pull on Earth's water, though:

  • It would pull on everything on and underneath the Earth's surface, too.

  • This would increase Earth's volcanic activity,

  • and the frequency of other natural disasters,

  • like earthquakes and tsunamis.

  • Which are rarely good for life - or for humans.

  • On an even longer scale, this second moon

  • would even affect how long our day is.

  • Right now, our Moon is gradually slowing

  • Earth's rotation because it's orbiting around us

  • more slowly than we're spinning.

  • Its gravity is tugging on Earth and

  • creating a sort of drag.

  • But a second satelliteespecially one close to the Moon's size

  • would interfere with that process.

  • Exactly how, though, would, of course, depend on its orbit,

  • but for the sake of simplicity, let's say it orbited

  • in the same direction as our current Moon,

  • and was located a bit closer to Earth.

  • That satellite would help slow down our rotation,

  • and our days would get longer.

  • Which might sound kind of nice, because I could use

  • a couple extra minutes a day, until you realize

  • that satellite would also gradually creep outward

  • because of some specific orbital mechanics.

  • Eventually, it would smash into the Moon,

  • which would almost definitely bring about

  • some kind of Armageddon as debris

  • rained down upon the Earth.

  • Like I saidthe moonlight probably isn't

  • the thing we should be most worried about.

  • At the end of the day, of course the odds of

  • the Earth acquiring another Moon-like satellite are

  • very slim, but there is something to learn here.

  • These kinds of scenarios remind you of how important

  • the specific conditions around our planet are.

  • Like, if our Moon had a different orbit or mass,

  • our world could be much different.

  • So even though we usually take it for granted,

  • maybe we should appreciate our Moon a little bit more

  • look up there and say like - hey buddy, thanks,

  • you're really great.

  • You're always helping us out. Thanks for being a friend.

  • But don't try and pick up a third friend. Just us.

  • Just the two of us. Building castles in the sky.

  • Understanding how a second moon would affect

  • the Earth depends on an understanding of gravity

  • and other physics.

  • And if you're looking to build up your STEM skills

  • and learn how to solve problems like a scientist,

  • Oribel's VertiPlay Marble Run is one place to start.

  • The Marble Run is a “toy systemthat offers

  • a way to explore concepts like gravity and propulsion

  • by building something yourself and learning

  • through trial and error.

  • It comes in a modular set, so you can always

  • start small and add to your creation later.

  • The Marble Run is perfect for kids five years or older

  • or even adults who are up for a fun challenge.

  • No matter who you are, it will help you master basic

  • STEM skills and expand your creativity.

  • If you want to give it a try, you can get 15%t off

  • any VertiPlay Marble Run set or extension.

  • Just click the link in the description and use

  • promo code SCISHOW15.

  • [♪ OUTRO]

Thanks to VertiPlay STEM Marble Run for

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如果地球撿到第二個月球怎麼辦? (What If Earth Picked Up a Second Moon?)

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    林宜悉 發佈於 2021 年 01 月 14 日
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