シャドーイング練習: Astronomers Just Found Earth's Secret Second Moon - 動画で英語スピーキングを学ぶ

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In 2024, Earth was joined by a mini-moon that orbited around our planet for two months.
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It hung around, made a few laps, and then, like every polite guest, it left.
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It went back to resume its trip around the Sun.
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However, astronomers now say another rock has been tagging along with Earth not for weeks, but for six decades.
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It's rare and strange, now being classified as a quasi-moon.
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But what exactly does that mean?
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Is it like a backup satellite?
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Unlike our cool and mysterious moon that illuminates our nights and affects werewolves, a quasi-moon doesn't circle Earth.
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Instead, it orbits the Sun, but it does so almost in perfect sync with us, like a runner doing a marathon with you that keeps a similar pace.
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Space only seems calm.
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It's actually pretty chaotic.
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The Sun, the Moon, Earth, and even other planets are constantly tugging on each other and smaller objects like these rocks.
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Most asteroids can't hold this delicate balance for long.
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They either get nudged into a new orbit, pulled closer to Earth, or flung out into the vast reaches of space.
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That's why we're lucky to spot more than one or two at a time.
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Most just can't keep the balance.
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They belong to a bigger family called co-orbitals.
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In fact, astronomers group them into a few types based on how they move relative to Earth.
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But unlike the real Moon, that's been our companion since the very beginning, these visitors don't stick around forever.
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Some hang with us for a few decades, others for centuries, before drifting away because of the gravity of some other space object.
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Kind of like a dog running to your neighbor after smelling bacon.
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One other thing about quasi-moons is their size.
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Most are tiny, building-sized, or even smaller.
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They're also so dim that they can hide in plain sight among stars.
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Still, they're important.
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By studying them, astronomers learn how small near-Earth objects move and how long they can stay caught in Earth's gravity.
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Quasi-moons are closer than other asteroids on the same path, and it would be easier to reach them.
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One day, they might be used as stepping stones in space exploration.
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Earth has had a few of these tagalongs before.
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One of the most famous is 2016 H03, nicknamed Earth's Constant Companion.
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It's only about 300 feet wide, but it's been keeping pace with us for nearly a century.
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Researchers say it might keep up for centuries more.
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But what about the most recently discovered one?
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The researchers named it 2025 PN7.
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Like we said, it's already been with us for 60 years and will likely stay for around 68 more.
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For a long time, it remained undiscovered because of its tiny size, only about 62 feet across, which is about the length of a bowling lane.
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This also answers the question of whether you could see it yourself if you knew where to look.
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Its backstory is a bit of a mystery.
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Astronomers haven't figured out its composition yet.
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Right now, all we know for sure is its trajectory.
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Some quasi-moons are just near-Earth asteroids that fell into a perfect orbit.
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Others seem like they could be chunks of the moon itself.
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For instance, there's another quasi-moon named Kamo'o'a Loea
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that reflects light in almost the same way as the lunar rocks we brought back during the Apollo missions.
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Because of that, some researchers think it might actually be left over from a huge impact that happened long ago.
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There's also 2024 PT5, a temporary mini-moon from the end of last year.
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Tests showed that its surface looks like lunar basalt, suggesting it probably came from the moon.
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So, how do these quasi-moons pull off their cosmic balancing act?
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That's because it's just an orbital illusion.
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Remember, PN7, like other quasi-moons, isn't actually circling our planet.
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To us, it looks like the rock is scribbling lazy loops around Earth's path, like doodles in space.
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Yet, it never lags too much or gets too far.
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Astronomers call this a one-to-one resonance.
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In plain English, it makes a lap around the sun every time Earth does.
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Another fun question.
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If these fake moons are so close to Earth, why don't we just pull them in with our gravity?
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Especially since they're tiny and seem so near.
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That's because even though they belong to a group called near-Earth objects, quasi-moons are not that close.
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Our moon is hanging out about 239,000 miles away.
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These companions, though, are flying around the sun millions of miles out, way beyond Earth's gravitational pull.
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That pull exists within an area called the hillsphere, which is where Earth's gravity is stronger than the sun's.
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Think of Earth's gravity as a bubble with a radius of about a million miles.
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Anything inside can get caught, like the real moon.
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Step outside, and the sun takes over.
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This is exactly what happened to PT5.
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which was our legit satellite for two months in 2024.
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It dipped inside the hill sphere, and Earth's gravity took over.
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Once it happened, this object became known as a mini-moon.
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But because it was small and moving fast, it eventually slipped back out of that bubble, and the Sun's gravity pulled it away again.
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One other type of co-orbiter, aside from quasi-moons and mini-moons, is the so-called horseshoe orbiters.
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These space rocks don't stray far, but from Earth's point of view, they seem to swing ahead of us, slow down, then drift back behind, and repeat.
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It's like an undercover cop tailing you in traffic, but constantly switching lanes and doubling back so you don't notice the pattern.
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If you trace their motion from Earth, over time, it forms a giant horseshoe shape, hence the name.
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And these are just the main co-orbiters.
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There are actually more.
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Way ahead of us and way behind us in space, there are a few quirky rocks called Trojans.
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They're not just following right next to Earth like quasi-moons do.
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Instead, they found two special hiding spots.
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One 60 degrees in front of us and one 60 degrees behind.
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Imagine riding your bike and having a friend way ahead of you and another one way behind.
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both keeping the same speed.
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That's what Trojans do.
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Those spots are called Lagrange points, cozy hangout regions where the gravitational pulls from Earth and the Sun balance out perfectly.
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When they find themselves in one of those areas, they could be staying there for millions of years without drifting away.
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Jupiter, for example, has tons of these freeloaders.
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Earth has only a few.
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Then there are tadpole orbiters.
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Instead of sitting perfectly still in a Lagrange point, they wobble around it in lazy, bean-shaped loops.
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And if that's not confusing and overwhelming enough, there are also jumping Trojans.
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The indecisive ones.
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These guys can't pick a side.
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They'll spend a few thousand years staying in the front hammock, then slowly drift to one behind us and back again.
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Rare, weird, and kind of awesome.
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So even though Earth only has one big moon in the sky, we've actually got a whole gang of intrusive space tagalongs.
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Some loop, some trail, some hide in the corners.
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Now let's recap the superpowers of our moon.
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It can affect tides, slow down Earth's rotation, and even help stabilize our planet's tilt.
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Without the moon, our days would be shorter, our nights darker
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and the seasons way more chaotic the moon also acts like a giant shield sweeping up
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or deflecting some space rocks that might otherwise smack into earth
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and let's not forget its cultural influence it's been inspiring myths calendars love songs
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and millions of melancholic walks in the middle of the night
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fake moons can't compete however they are important in their own
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way each new quasi moon we find helps us understand how these little rocks survive in all
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that cosmic chaos by learning about our environment we also learn something about ourselves they sharpen our detection skills
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and help us improve our models so
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while they'll never shine in the night sky they still play
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a quiet role in helping us understand our quirky cosmic neighborhood That's it for today.
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So hey, if you pacified your curiosity, then give the video a like and share it with your friends.
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Or if you want more, just click on these videos and stay on the bright side.
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このレッスンの語彙とスピーキングのポイント

この動画には、シャドーイング用の文が110文、単語が1415語あります。 音声の長さは9:21です。 話す速さは1分あたり約151語で、日常会話に近い自然なペースです。 英語の頻出3,000語に含まれる単語は81%だけなので、語彙は難しめです。

この動画の重要語彙

動画に出てくる覚えておきたい単語15語を、発音と意味つきで紹介します。

単語発音意味
orbit 名詞/ˈɔɹ.bɪt/軌道
loop 名詞/luːp/ループ
companion 名詞/kəmˈpæn.jən/仲間, 友人
researcher 名詞/ˈɹiˌsɝ.t͡ʃɚ/研究員, 研究者
cosmic 形容詞/ˈkɑz.mɪk/宇宙の
asteroid 名詞/ˈæst(ə)ɹɔɪd/小惑星
plain 名詞/pleɪn/平地, 平野
belong 動詞/bɪˈlɒŋ/所属する, 属する
pace 名詞/peɪs/歩幅
satellite 名詞/ˈsætəlaɪ̯t/衛星
lazy 形容詞/ˈleɪ̯zi(ː)/ナマケモノ, 怠惰な
bubble 名詞/ˈbʌbəl/泡
vast 形容詞/væst/広大な, 莫大な
relative 名詞/ˈɹɛl.ə.tɪv/親戚, 身内
temporary 形容詞/ˈtɛmp(əˌɹ)ɛɹi/暫くの, 暫時の

動画に出てくる句動詞

単語意味
slow down 動詞遅らせる
take over 動詞引き受ける

この動画の文法

話し手がよく使っている文型を、動画の実際の表現とともに紹介します。

文型動画での表現
受動態 be + 過去分詞 — 誰がするかより、何が起きるかに焦点を当てるwas joined · being classified · be left
関係詞節 who / which + 節 — 人や物について情報を加えるacross, which is · hillsphere, which is

注意したい発音

話し手はcan't, don't, they'reなど、短縮形や弱形を19回使っています。聞こえたとおりの短い形で発音しましょう。

  • 「th」の音: marathon /ˈmæɹəθən/, myth /mɪθ/
  • 「sh」と「zh」の音: composition /ˌkɑm.pəˈzɪʃ.ən/, shield /ˈʃild/, exploration /ˌɛkspləˈɹeɪʃən/, shine /ʃaɪn/, rotation /ɹoʊˈteɪʃən/
  • 長い単語（アクセントの位置に注意）: temporary /ˈtɛmp(əˌɹ)ɛɹi/, composition /ˌkɑm.pəˈzɪʃ.ən/, exploration /ˌɛkspləˈɹeɪʃən/, mysterious /mɪˈstɪɹi.əs/, curiosity /ˌkjʊɹ.iˈɑ.sə.ti/

この動画での練習方法

  1. まず声を出さずに動画を最後まで聞き、知らない単語をメモします。
  2. まず0.75倍速で一文ずつシャドーイングし、慣れてきたら通常の速度に戻します。
  3. 自分の声を録音して元の音声と比べます。orbit, loop, companionなどの単語に特に注意しましょう。

シャドーイングとは？英語上達に効果的な理由

シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。

シャドーイングのやり方: ステップ別の完全ガイドを読む →