Coral reefs are fragile and in danger worldwide, but a growing movement to restore them is based on the science of breaking off pieces in order to grow more, known as coral gardening.

It works like this: marine biologists cut off the tips of live branching corals, hang the pieces on man-made underwater trees where they grow, and later "outplant" them on real reefs on the ocean floor.

A solar-powered aircraft on a round-the-world flight was high above the Pacific Ocean Tuesday, over a quarter of the way to Hawaii after leaving Japan, the mission website showed.

Solar Impulse 2 had travelled 26 percent of the way to the tropical US state by 0500 GMT, having flown 2,204 kilometres (1,377 miles) with 6,136 kilometres more to go, according to the project.

Australian zookeepers Tuesday said they had successfully fostered an orphaned tree kangaroo with a surrogate wallaby in a rare case after its mother was crushed by a branch.

The Goodfellow's tree kangaroo, named Makaia by its carers at Adelaide Zoo in South Australia, was just five weeks old and at risk of dying after its three-year-old mother was killed by a falling tree branch in November.

Germany's oldest remaining nuclear reactor has been shut down, part of a move initiated four years ago to switch off all its nuclear plants by the end of 2022.

The Grafenrheinfeld reactor in the southern state of Bavaria was taken offline as scheduled overnight, authorities and operator E.ON said Sunday.

The global space industry is reeling after three cargo disasters in less than a year have delivered a costly blow to efforts to supply astronauts aboard the International Space Station.

The explosion of SpaceX's Falcon 9 rocket on Sunday also raised new questions about whether U.S. rockets are safe enough to start launching astronauts to space as planned in 2017.

Brazil will soon open Latin America's first elephant sanctuary, and its three initial residents will be retired circus animals in need of a safe haven, a report said Sunday.

"The idea is to build an establishment like the Elephant Sanctuary in Tennessee in the United States," Junia Machado, president of the Santuario de Elefantes Brasil group that is behind the project, told the Folha de S. Paulo newspaper.

The revolutionary Solar Impulse 2 aircraft passed "the point of no return" Monday after it left Japan bound for Hawaii, the most ambitious leg of its quest to circumnavigate the globe powered only by the sun.

Swiss pilot Andre Borschberg, 62, left the city of Nagoya around 3:00 am (1800 GMT), five days after weather problems forced the organizers to cancel an earlier attempt.

A conservation group plans to move seven lions from South Africa to a national park in Rwanda, where it says the lion population was wiped out 15 years ago.

The five female lions and two males will be transferred beginning Monday to Rwanda's Akagera National Park by truck and plane in a journey lasting more than 24 hours, said African Parks, a South Africa-based group that runs national wildlife parks in Africa.

An unmanned SpaceX rocket exploded less than three minutes after liftoff from Cape Canaveral, Florida on Sunday, in the first major disaster for the fast-charging company headed by Internet tycoon Elon Musk.

The accident was the third in less than a year involving U.S. and Russian supply ships bound for the International Space Station, and raised new concerns about the flow of food and gear to the astronauts living in orbit.

President Juan Manuel Santos says an oil spill triggered by a rebel attack on a pipeline the worst environmental disaster in Colombia's history.

Santos made the comments Friday while visiting the southern port city of Tumaco to survey damage from the June 22 bombing by the Revolutionary Armed Forces of Colombia.