Scientists Say

A weekly word defined, in a sentence and in context. Click here to find the alphabetized list.

  1. Chemistry

    Scientists Say: Isotope

    An isotope is a variety of an element that has the same number of protons but a different number of neutrons — or neutrally charged particles.

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  2. Planets

    Scientists Say: Eclipse

    How the sun, moon and Earth line up determines whether there’s a solar or lunar eclipse.

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  3. Chemistry

    Scientists Say: Atomic number

    How do you know where an element sits in the periodic table? Count its protons to get its atomic number.

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  4. Plants

    Scientists Say: Guttation

    When water vapor can’t escape a plant, it might force its way out through a process called guttation.

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  5. Plants

    Scientists Say: Stomata

    Plants have pores they open and close to let oxygen, carbon dioxide and water vapor in and out. These pores are called stomata.

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  6. Brain

    Scientists Say: Synapse

    When brain cells need to pass messages, they do it without touching, across a space called a synapse.

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  7. Planets

    Scientists Say: Dwarf planet

    Dwarf planets are distinct from the full-size models. A little too small, they also have a lot of space stuff filling their path around the sun.

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  8. Life

    Scientists Say: ATP

    This chemical is a bit like a rechargeable battery. Cells build and break apart its chemical bonds to store and release energy.

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  9. Planets

    Scientists Say: Goldilocks zone

    Not too hot, not too cold. Just right. This is the region around a star where water could be a liquid, instead of a solid or gas.

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  10. Physics

    Scientists Say: Dark matter

    Most of the universe isn’t made of stuff we can see. Scientists think some of it might be made of dark matter — matter that emits no radiation.

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  11. Animals

    Scientists Say: Hibernation

    Hibernation is more than a deep sleep. Animals that hibernate lower their body temperature and reduce their body activities for months.

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  12. Health & Medicine

    Scientists Say: Hyperthermia

    If our body temperatures rise too high, we can suffer from hyperthermia.

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