Planetary Science

  1. Planetary Science

    Ice among the rocks

    A newly discovered trio of icy comets, hidden among the thousands of rocks in the main asteroid belt, may be part of a previously unknown class and a primary source of water for the dry, early Earth.

    By Ron Cowen
  2. Planetary Science

    Brilliant! Tenth planet turns out to be a shiner

    Xena, unofficially called the 10th planet, is the second-most-shiny known object in the solar system.

    By Ron Cowen
  3. Planetary Science

    Another visitor to Mars

    The newest spacecraft from Earth arrived at the Red Planet on March 10.

    By Ron Cowen
  4. Planetary Science

    Making Mercury

    New computer simulations of Mercury's violent formation account for the planet's abundance of heavy elements and also reveal that some of the debris generated by the collision could have found its way to Earth and Venus.

    By Ron Cowen
  5. Planetary Science

    Another red spot, by Jove

    Jupiter has developed a second red spot, which is now visible in the predawn sky with a telescope 10 inches or larger.

    By Ron Cowen
  6. Planetary Science

    Propelling Evidence: Cassini finds clues to source of Saturn’s rings

    Four propeller-shaped gaps in one of Saturn's main rings are the latest evidence that a shattered moon produced the planet's dazzling hoops.

    By Ron Cowen
  7. Planetary Science

    Pluto’s posse

    Images taken by the Hubble Space Telescope on Feb. 15 confirm that Pluto has two small, previously unknown moons.

    By Ron Cowen
  8. Planetary Science

    Eyeing a Saturn storm

    The Cassini spacecraft recently captured an image of the most powerful storm ever seen on Saturn.

    By Ron Cowen
  9. Planetary Science

    Stellar passage yields Charon’s girth

    By observing Pluto's moon Charon passing in front of a star, astronomers have obtained precise measurements of the moon's radius and density.

    By Ron Cowen
  10. Planetary Science

    One star better than two?

    Rather than disrupting the planet-forming process around another star, a nearby companion may sometimes enhance it, new computer simulations suggest.

    By Ron Cowen
  11. Planetary Science

    Moon spray

    The Cassini spacecraft has found conclusive evidence that the south pole of Saturn's moon Enceladus spews jets of icy particles into space.

    By Ron Cowen
  12. Planetary Science

    Red Planet Express: Mars spacecraft traces a watery tale

    A Mars-orbiting spacecraft has provided new details about when and where liquid water existed on the planet.

    By Ron Cowen