The first Chinese ship has travelled from the Pacific to Atlantic via the Arctic along the Russian coast, an Icelandic scientist who participated on the expedition said Friday.

The Chinese icebreaker Xuelong, or Snow Dragon, docked in Iceland after having sailed the so-called Northern Sea Route from the Pacific, Egill Thor Nielsson told Agence France Presse.

U.S. emissions of carbon dioxide blamed for climate change fell in 2011 and have slipped to a 20-year low this year as the world's largest economy uses more natural gas and less coal, data shows.

The surprise drop from the world's second biggest emitter comes despite the lack of legislation on climate change but it was unclear if the change marked a trend or would be enough to meet goals on fighting global warming.

A team of amateur cave explorers and arachnologists has found a new family of spiders in caves and old-growth redwood forests in Oregon and California, U.S. researchers said Friday.

Entomologists at the California Academy of Sciences said the spider, named Trogloaptor -- or "cave robber" -- for its lethal front claws, had such unique evolutionary features that it represented not just a new genus or species, but also a new family of spiders.

The U.S. space agency NASA's Mars rover Curiosity will make a wide detour to explore a "cool" geographical hot spot on Mars, scientists said Friday.

The scientists also reported they found temperatures in the Red Planet's Gale Crater to be just above freezing, the first monitoring of Mars temperatures in three decades.

A polar bear in a German zoo died and its companion barely survived after they fell sick with a mutated encephalitis virus that originated in zebras, scientists say.

The finding is a concern, for it shows how rare species in zoos can be at risk from species-jumping pathogens, they say.

Belgium stepped up controls on nuclear safety that found cracks in the casing of an ageing reactor and led to two sites now closing after learning of signs of fissures in French atomic power plants, the national watchdog said Thursday.

Controls carried out in 2004 on a site in southern France revealed "indications of fissures" in base material "perpendicular to the (reactor's) surface" which were "dangerous", the head of Belgium's federal agency for nuclear safety AFCN Willy de Roovere told media.

Australian scientists said Friday there was now "striking evidence" of extensive southward migration of tropical fish and declines in other species due to climate change, in a major ocean report card.

Compiled by more than 80 of Australia's leading marine experts for the government science body CSIRO, the snapshot of global warming's effects on the island continent's oceans warned of "significant impacts".

Scientists have found a cosmic supermom. It's a galaxy that gives births to more stars in a day than ours does in a year.

Astronomers used NASA's Chandra (SHAWN'-drah) X-Ray telescope to spot this distant galaxy creating about 740 new stars a year. By comparison, our Milky Way galaxy spawns about one new star each year.

Seychelles and Germany have the healthiest seas of any inhabited territory, while Sierra Leone has the unhealthiest, according to a new index that says many oceans score poorly for biodiversity and as a human resource.

Topping the list with a score of 86 out of 100 was the uninhabited South Pacific territory of Jarvis Island, owned by the United States, as well as a clutch of other unpopulated Pacific Ocean islands.

A flight test of an experimental unmanned vehicle designed to fly at hypersonic speeds has ended in failure, the U.S. Air Force said Wednesday.

The X-51A Waverider was dropped from a B-52 bomber Tuesday and launched by a rocket booster as planned but the flight was over in seconds after a control fin malfunctioned, the Air Force said in a statement.