Sydney's skyline plunged into darkness on Saturday as the city cut its lights for the "Earth Hour" campaign against climate change, kicking off an event which will travel around the globe.

Organizers expect hundreds of millions of people across some 150 countries to turn off their lights for 60 minutes on Saturday night -- at 8:30pm local time -- in a symbolic show of support for the planet.

New rock dating techniques have helped narrow the timeframe of a chain of massive volcanic eruptions that wiped out half the world's species 200 million years ago, a study said Thursday.

The result is the most precise date yet -- 201,564,000 years ago -- for the event known as the End-Triassic Extinction, or the fourth mass extinction, said the study in the journal Science.

A new examination of what is essentially the universe's birth certificate allows astronomers to tweak the age, girth and speed of the cosmos, more secure in their knowledge of how it evolved, what it's made of and its ultimate fate.

Sure, the universe suddenly seems to be showing its age, now calculated at 13.8 billion years — 80 million years older than scientists had thought. It's got about 3 percent more girth — technically it's more matter than mysterious dark energy — and it is expanding about 3 percent more slowly.

The European Space Agency (ESA) on Thursday unveiled the most detailed map yet of relic radiation from the Big Bang, revealing new data it hopes will shed light on the creation and expansion of our Universe.

The 50-million pixel, all-sky image of the oldest light adds an edge of precision to some existing cosmological theories, defining more precisely the composition of the Universe and its age -- about 80 million years older than previously thought.

China's coastal waters are suffering "acute" pollution, with the size of the worst affected areas soaring by more than 50 percent last year, an official body said.

The State Oceanic Administration (SOA) said 68,000 square kilometers (26,300 square miles) of sea had the worst official pollution rating in 2012, up 24,000 square kilometers on 2011.

Japanese researchers said Thursday they have found a rich deposit of rare earths on the Pacific seabed, with reports suggesting it could be up to 30 times more concentrated than Chinese reserves.

Mud samples taken from 5,800 meters (19,000 feet) below the waves contained highly concentrated amounts of the precious minerals, which are vital for high-tech manufacturing and used in products including wind turbines and iPods.

Five Greenpeace activists on Thursday chained themselves to Jerusalem's soaring Bridge of Strings demanding that U.S. President Barack Obama halt exploratory drilling in the Arctic, an Agence France Presse correspondent said.

Wearing white overalls and yellow helmets, the five used climbing gear to inch up the metal cables which spans a busy intersection at the entrance to the city.

Researchers in Germany said Tuesday they have completed the first high-quality sequencing of a Neanderthal genome and are making it freely available online for other scientists to study.

The genome produced from remains of a toe bone found in a Siberian cave is far more detailed than a previous "draft" Neanderthal genome sequenced three years ago by the same team at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

Hong Kong is one of the world's worst cities for light pollution with night skies around 1,000 times brighter than globally accepted levels, researchers said Wednesday ahead of this year's Earth Hour event.

A study by Hong Kong University found that brightness levels in the southern Chinese city's popular shopping district of Tsim Sha Tsui were 1,200 times greater than the international dark sky standard -- a measurement void of manmade light.

Scientists on Wednesday announced they had peeked into the DNA of the giant squid, seeking to demystify a deep-sea creature that has haunted sailors' dreams for centuries.

But their findings published Wednesday threw up some tantalizing questions in turn.