Feature

  1. Physics

    Year in Review: Below absolute zero, but hot

    Lab trickery pushes atoms to a negative temperature.

    By Andrew Grant
  2. Astronomy

    Year in Review: Death of a planet hunter

    The Kepler space telescope finishes a brilliant career.

    By Andrew Grant
  3. Astronomy

    Year in Review: Voyager 1 reaches interstellar space

    The planetary probe is the first human-made object to break out of the heliosphere.

    By Andrew Grant
  4. Health & Medicine

    Year in Review: Putting kids at risk

    U.S. parents increasingly are delaying their children’s vaccination.

    By Nathan Seppa
  5. Climate

    Year in Review: Carbon dioxide levels pass milestone

    Although scientists are confident about humankind’s role in climate change, they still have a lot to learn about the magnitude and timing of future climate shifts.