Across the vast Pacific, the mighty bluefin tuna carried radioactive contamination that leaked from Japan's crippled nuclear plant to the shores of the United States 6,000 miles away — the first time a huge migrating fish has been shown to carry radioactivity such a distance.

"We were frankly kind of startled," said Nicholas Fisher, one of the researchers reporting the findings online Monday in the Proceedings of the National Academy of Sciences.

Richard Leakey predicts skepticism over evolution will soon be history.

Not that the avowed atheist has any doubts himself.

Even robots like to have fun. NASA's rover on Mars showed off its playful side by snapping a picture of its own shadow. It's the latest self-portrait since the rover, named Opportunity, landed on the red planet in 2004.

The photo was taken in March and NASA released it this week. The solar-powered, six-wheel rover was at an outcrop on the rim of a massive crater. The late afternoon sun set the crater aglow and Opportunity waited for just the right lighting to send a postcard back to Earth.

The private company SpaceX made history Friday with the docking of its Dragon capsule to the International Space Station, the most impressive feat yet in turning routine spaceflight over to the commercial sector.

It marked the first time a business enterprise delivered a supply ship to the space station.

Astronomers are gearing for one the rarest events in the Solar System: an alignment of Earth, Venus and the Sun that will not be seen for another 105 years.

The celestial ballet known as the Transit of Venus is one of the most eagerly-awaited events in sky watching, an episode that has advanced the frontiers of knowledge, sometimes with dramatic consequences.

Climate researchers said Thursday the planet could warm by more than 3.5 degrees Celsius (6.3 degrees Fahrenheit), boosting the risk of drought, flood and rising seas.

The U.N.'s target is a 2 C (3.6 degree Fahrenheit) limit on warming from pre-industrial levels for manageable climate change.

Argentine experts have discovered the near-complete remains of a new species of Jurassic-era dinosaur that stood on its rear legs and had tiny arms, a leading paleontologist said Thursday.

The find belongs to the Abelisaurus family, "the most common carnivorous species in the southern hemisphere during the Cretaceous Period," some 70 to 100 million years ago, paleontologist Diego Pol told Agence France Presse.

The U.S. company SpaceX on Thursday prepared for the climax of its Dragon capsule's landmark mission to the International Space Station with a high-stakes bid to latch on to the orbiting research lab.

The unmanned, cargo-carrying supply ship on Friday aims to become the first privately owned craft to berth with the $100 billion space station, thereby restoring U.S. access to the space outpost after the shuttle program's end.

Australian researchers tracking life on the Great Barrier Reef said Friday they have proven a long-debated theory that fish born in marine reserves boost overall ocean stocks by dispersing widely.

The team, from the ARC Centre of Excellence for Coral Reef Studies, used DNA testing to track the spread of baby coral trout and stripey snappers from their spawning on the reef's Keppel Island marine reserve, where fishing is illegal.

Street lights have an unexpectedly strong effect on insect populations, favoring some species while punishing others, according to a study released Wednesday that raises new questions about human impact on wildlife.

Researchers led by Thomas Davies at the University of Exeter, southwestern England, spent three days in August 2011 placing insect traps around Helston, a small town in Cornwall.