Researchers have unearthed a 25-foot-long (7.6-meter-long) Tyrannosaurus rex-like dinosaur with the probable remnants of a brain tumor still preserved inside its skull cavity. The debilitating cancer may have affected the predator's balance, explaining the many wounds and fractures recorded in its skeleton.

Catastrophic asteroid impacts are gaining a credible edge over violent volcanic eruptions as the greatest killers Earth has ever seen, according to two pieces of scientific detective work reported in tomorrow's issue of the journal Science.

Penguin rookeries in Antarctica—weather permitting—will be audience to a total solar eclipse Sunday as the moon slips between Earth and the sun and casts a narrow band of the icy continent into daytime darkness. A few hundred humans, too, hope to catch the celestial show. They've paid thousands of dollars to journey to—or over—Antarctica, the only landmass where the minutes-long event will be visible.

The number of rorqual whale species swimming in the world's oceans has jumped to eight from six, according to new research by a team of Japanese scientists published in tomorrow's issue of the science journal Nature. The scientists identified a new species of rorqual, Balaenoptera omurai, and resolved a long-standing debate by showing that other whales previously referred to as Bryde's whale are indeed distinct species: (B. brydei) and (B. edeni).

The Mekong River's giant catfish (Pangasianodon gigas) is on the path to extinction. Today's release of the World Conservation Union (IUCN) updated 2003 Red List of Threatened Species shows that the flagship species of the storied river in Southeast Asia is classified as critically endangered, its numbers further reduced from its classification as endangered in the previous IUCN Red List.

Shooting stars should be visible tonight, the traditional climax of the Leonid meteor shower. Sky watchers in the Americas will observe peak activity early Wednesday morning, however, when up to 17 meteors every 15 minutes will be visible.

Two astronomers say Earthlings could make contact with alien beings from other planets sometime in the next 20 years. The researchers, authors of a new book outlining their case, say a direct visit is improbable and that radio signal communication is more likely.

Divided ecosystems can fatally limit an animal's territory or obstruct migration routes, sending species spiraling towards extinction. Now, scientists studying a common tropical tree in a Tanzanian mountain range found that forest fragmentation may also harm plants and animals in less obvious ways, severing the relationships both need to survive.

Four robots of science and science fiction renown were inducted into the Robot Hall of Fame at an awards ceremony held last night in Pittsburgh, Pennsylvania. The Mars Sojourner Pathfinder and R2-D2 were among the groundbreaking machines, both real and imagined, honored in the inaugural ceremony.

Scientists in Canada and Scotland report that schools of Atlantic and Pacific herring communicate by farting. Researchers suspect herring hear the bubbles as they're expelled, helping the fish form protective shoals at night. It's the first-ever study to suggest fish communicate by breaking wind. Full story and audio:

When Hurricane Isabel roared onto the Outer Banks of North Carolina two months ago, storm waters washed U.S. Highway 12 out to sea. Now agencies are pumping sand back into "Isabel Inlet" and plan to restore the road by the end of November. But is this an exercise in futility?

Chances for stargazers to witness a blazing fireball streak across the night sky improve as the Taurid meteor shower peaks over the next few weeks. The meteors' slow velocity and brightness make them of particular interest to astro-photographers.

On Saturday night the full moon will slip into Earth's shadow and darken to an orange-reddish glow, giving sky-watchers their second chance this year to catch an astronomer's delight: a total lunar eclipse. The celestial show will be visible throughout most of the Americas, Europe, Africa, and parts of Asia.

Dudley Foster holds the record for the most time spent on the deep-ocean floor. A pilot of the Woods Hole submersible Alvin, he has completed 552 dives from the Galápagos' hydrothermal vents to the Titanic. A related story airs tonight on our U.S. cable television program National Geographic On Assignment.

When it comes to the primal urge to pass genes on to the next generation, cockerels are a sophisticated lot. Scientists have learned that the wild male chickens dole out more or less sperm while mating depending on how much competition they face. Female promiscuity and ornamentation also play a role.