Shadowing Practice: Where Did Earth's Water Come From? - Learn English Speaking with Video
Creating lesson...
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Unlike every other planet in our solar system, Earth's surface is 70 % liquid water, which while useful for life, is also kind of weird,
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because everything we know about how and when our planet formed says Earth's surface should be bone dry.
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The story goes like this.
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Our solar system formed from the collapse of a large cloud of dust and gas.
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The dense blob of gas at the center ignited to form the sun, which as a young unstable star unleashed a fierce solar wind.
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And over time, this stream of charged particles pushed the remaining gas cloud farther and farther out, leaving only solid particles behind to clump together into rocks,
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planetesimals, and finally, the rocky planets of the inner solar system that we know today.
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And here's the problem.
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Water, in the form of ice, couldn't have been one of the solid particles that stuck around to form our planet, because the early inner solar system was far too hot for frozen water,
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and any water vapor would have been blasted away by the solar wind.
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So if Earth didn't start off with water, how did we end up with such splendid oceans?
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We know H2O wasn't manufactured here over the eons, because natural processes like combustion,
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breathing and photosynthesis create and destroy roughly equal amounts of water, and either way, the amounts in question are so minuscule that they can't account for the abundance of water on the planet.
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Since Earth's water was neither part of the original package nor manufactured here, it must have flown in from far away, on meteoroids or comets or other bodies originating in the outer solar system,
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where they were far enough from the sun for frozen water to survive.
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The dirty ice balls we call comets are a logical candidate for the source of our water, but were ruled out when we discovered that they were far richer in heavy hydrogen than earth water.
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Heavy hydrogen has a neutron as well as a proton in its nucleus, and for every million hydrogen atoms in earth water, about 150 are heavy ones,
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while typical comet water has twice that many.
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These mismatched chemical signatures suggest that Earth's water couldn't have arrived on comets.
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It turns out that the most likely source for Earth's water is a type of meteorite called a carbonaceous chondrite.
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Chondrite is just the name given to the class of stony meteoroids that most commonly strike the Earth.
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But only the carbonaceous chondrites contain water, as well as lots of carbon if you couldn't tell from their name.
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They have water in them because they formed out beyond the sun's frost line, and what's more, their water has levels of heavy hydrogen similar to that of earth water,
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strongly suggesting that these earth crashers are the source of our ice caps, clouds, rivers, and oceans.
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And thus the water that turned our planet into a blue marble came, quite literally, out of the blue.
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Vocabulary and speaking notes for this lesson
This B2 speaking lesson is built on the video “Where Did Earth's Water Come From?”. The speaker keeps coming back to these words: solar, planet, earth, comet, hydrogen. This video has 25 sentences and 496 words to shadow. The speech runs for 2:24. The speaker talks fast, about 206 words per minute, so expect linked and reduced sounds. Only 80% of the words are among the 3,000 most common in English, so the vocabulary is demanding.
Key vocabulary in this video
The 15 most advanced words in the video, with pronunciation and meaning:
| Word | Pronunciation | Meaning |
|---|---|---|
| comet noun | /ˈkɒmɪt/ | A small Solar System body consisting mainly of volatile ice, dust and particles of rock whose very eccentric solar orbit periodically brings it close enough to… |
| hydrogen noun | /ˈhaɪdɹəd͡ʒ(ə)n/ | The lightest chemical element (symbol H), with an atomic number of 1 and atomic weight of 1.008. |
| chondrite noun | /ˈkɒndɹaɪt/ | A meteorite consisting of rock containing chondrules. |
| particle noun | /ˈpɑɹtək(ə)l/ | A very small piece of matter, a fragment; especially, the smallest possible part of something. |
| carbonaceous adjective | /kɑːbəˈneɪʃəs/ | Of, relating to, rich in, or yielding carbon, or a compound of carbon. |
| meteoroid noun | A relatively small (sand- to boulder-sized) fragment of debris in a star system that produces a meteor when it hits the atmosphere | |
| freeze verb | /ˈfɹiːz/ | Especially of a liquid, to become solid due to low temperature. |
| crasher noun | One who crashes. | |
| ignite verb | /ɪɡˈnaɪt/ | To set fire to (something), to light (something) |
| meteorite noun | /ˈmi.ti.əˌɹaɪt/ | A metallic or stony object or body that is the remains of a meteoroid. |
| minuscule noun | /ˈmɪnəˌskjul/ | A lowercase letter. |
| mismatch noun | /ˈmɪs.mæt͡ʃ/ | Something that does not match; something dissimilar, inappropriate or unsuitable. |
| neutron noun | /ˈnu.tɹɑn/ | A subatomic particle forming part of the nucleus of an atom and having no charge; it is a combination of an up quark and two down quarks. |
| originate verb | /əˈɹɪd͡ʒɪneɪt/ | To cause (someone or something) to be; to bring (someone or something) into existence; to produce or initiate a person or thing. |
| photosynthesis noun | /ˌfoʊ.toʊˈsɪn.θə.sɪs/ | Principally, oxygenic photosynthesis, any process by which plants and algae convert water and carbon dioxide into carbohydrates and waste oxygen using solar… |
Phrasal verbs you will hear
| Word | Meaning |
|---|---|
| rule out verb | To cross an item out by drawing a straight line through it, as with a ruler. |
| turn out verb | To end up; to result. |
Pronunciation to watch
The speaker uses 6 contractions and reduced forms, such as couldn't, can't, didn't. Say them the short way, as you hear them.
- The “sh” and “zh” sounds: carbonaceous /kɑːbəˈneɪʃəs/, unleash /ʌnˈliʃ/
- Long words — get the stress right: carbonaceous /kɑːbəˈneɪʃəs/, meteorite /ˈmi.ti.əˌɹaɪt/, originate /əˈɹɪd͡ʒɪneɪt/, photosynthesis /ˌfoʊ.toʊˈsɪn.θə.sɪs/
How to practise with this video
- Listen to the whole video once without speaking and note the words you do not know.
- Start at 0.75× speed, shadow it sentence by sentence, then go back to normal speed once it feels easy.
- Record yourself and compare with the original, paying attention to words like comet, hydrogen, chondrite.
What is the Shadowing Technique?
Shadowing is a science-backed language learning technique originally developed for professional interpreter training and popularized by polyglot Dr. Alexander Arguelles. The method is simple but powerful: you listen to native English audio and immediately repeat it out loud — like a shadow following the speaker with just a 1–2 second delay. Unlike passive listening or grammar drills, shadowing forces your brain and mouth muscles to simultaneously process and reproduce real speech patterns. Research shows it significantly improves pronunciation accuracy, intonation, rhythm, connected speech, listening comprehension, and speaking fluency — making it one of the most effective methods for IELTS Speaking preparation and real-world English communication.