Scientists Say

A weekly word defined, in a sentence and in context.

  1. Life

    Scientists Say: Mitochondrion

    Mitochondria are structures inside cells that converts certain chemicals into adenosine triphosphate — a molecule cells use as energy.

    By
  2. Space

    Scientists Say: Supernova

    When a star has too much mass, it can explode. The explosion is called a supernova.

    By
  3. Brain

    Scientists Say: Hippocampus

    The hippocampus is an area of the brain that is essential for forming new memories.

    By
  4. 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.

    By
  5. Planets

    Scientists Say: Eclipse

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

    By
  6. 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.

    By
  7. Plants

    Scientists Say: Guttation

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

    By
  8. 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.

    By
  9. Brain

    Scientists Say: Synapse

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

    By
  10. 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.

    By
  11. 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.

    By
  12. 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.

    By
Use up and down arrow keys to explore.Use right arrow key to move into the list.Use left arrow key to move back to the parent list.Use tab key to enter the current list item.Use escape to exit the menu.Use the Shift key with the Tab key to tab back to the search input.