SCIENCE

Notebook

Fla. Gator Encounters Triple

The number of alligator sightings and attacks in Florida has nearly tripled in recent decades, according to a paper being published today in the journal Wilderness & Environmental Medicine.

As more Americans move to coastal communities and the country's alligator population continues to rebound, humans are increasingly encountering the once-endangered species. In Florida alone, the number of alligator attacks has risen from an annual average of five between 1948 and 1986 to an average of 14 between 1986 and 2005, said Ricky L. Langley, a medical epidemiologist at North Carolina's Department of Health and Human Services. The number of "nuisance complaints" or sightings in Florida increased from 5,000 in 1978 to nearly 15,000 in 1998.

"It's pretty much a straight line going up," Langley said in an interview, adding that Americans "just have to be more careful, and be on the lookout when they're on the water or on golf courses."

Florida leads the nation in alligator sightings; Louisiana reported 4,000 alligator encounters last year while Georgia and Texas each had about 450. Alabama followed with almost 250, and Arkansas reported just under 100 alligators in 2004.

The trend marks a sharp departure from the late 1960s, when federal officials listed the American alligator as an endangered species. U.S. alligators, which made it off the endangered species list in 1987, now number more than 3 million.

-- Juliet Eilperin

Ceres: The New Water Planet?

For years astronomers have tried to look closely at Ceres, the largest asteroid in the asteroid belt, a nearly opaque target so featureless that scientists could not even be sure of its shape.

But with the help of the Hubble Space Telescope, a team of researchers obtained enough images in enough detail to determine that Ceres is quite likely a "mini-planet" with enough gravity to make it almost spherical, and suggesting that, like Earth, it may have different layers, including a mantle composed mostly of water ice. The research was reported last week in the journal Nature.

Using Hubble's Advanced Camera for Surveys, the team tracked Ceres through its full nine-hour rotation, and with 700 pixels in each image were able to follow a "bright spot" as it moved around the asteroid, enabling them to determine its polar and equatorial axes.

Team member Lucy McFadden of the University of Maryland said scientists had thought that Ceres was homogeneous in composition because of its smooth surface and its low-density surface crust.