Tuesday, May 28, 2002
These days, many young people know the details of the planets and star systems that populate George Lucas' imaginative universe, but have trouble keeping straight the planets in our own solar system -- or for that matter knowing that, in fact, the earth revolves around the sun. But in terms of real astronomical excitement, the drama on Tatooine or Naboo doesn't hold a candle (or should we say a light saber) to the discovery of 11 more moons orbiting Jupiter, moons that uncharacteristically rotate in the opposite direction of the massive planet that holds them in thrall.
It was nearly 400 years ago -- Jan. 7, 1610 -- that Galileo Galilei first observed four planets in the vicinity of Jupiter through a telescope he had made. He shortly realized that what he saw were not planets but moons of Jupiter. Later named Io, Europa, Ganymede and Callisto, the satellites, since the mid-1800s, have been referred as the Galilean moons.
But the tiny moons discovered recently could never have been seen by Galileo. While Callisto is the size of Mercury, the new discoveries are much smaller, with estimated diameters between 1.2 and 2.4 miles. They are much farther out, roughly 12 million miles from Jupiter. To find them, astronomers used a telescope atop the Hawaiian dormant volcano Mauna Kea and one of the largest digital imaging cameras in the world. A University of Hawaii observatory was used to verify their unusual orbital paths.
Exciting discoveries
The team, led by astronomer David Jewitt and graduate student Scott Sheppard, discovered 11 other moons orbiting Jupiter in January 2001, which with their latest findings brings to 39 the number of Jovian moons identified. There may be many more.
Because of the moons' strange orbits, researchers believe that the moons were formed elsewhere but were somehow captured by the gravitational pull of the gigantic planet when it was yet young
Giant planets "capturing" small moons from some place in space does indeed sound like the plot for the next science fantasy adventure. But this is the language of real scientists, not cinematic voyageurs, who must trust to contemporary technology not to special effects.
The United States needs storytellers like George Lucas or Robert A. Heinlein and Arthur Asimov before him. But this nation also needs scientists like Jewitt and Sheppard who are able to see the adventure in the telescope that others see on the screen or in the pages of a book.