Some 7,000 light years away, Einstein's theory of general relativity has stood up to its most intense test yet, scientists said on Thursday.

The project involved observing a massive, fast-spinning star called a pulsar, and its companion white dwarf -- a smaller but very dense star that is dying, having lost most of its outer layers -- doing a dizzying orbital dance.

Ukrainians on Friday lit candles and laid flowers to remember the victims of the world's worst nuclear disaster at Chernobyl 27 years ago, as engineers pressed on with efforts to construct a new shelter to permanently secure the stricken reactor.

An explosion during testing in the early hours of April 26, 1986, sent radioactive fallout into the atmosphere that spread across Europe, particularly contaminating Belarus, Ukraine and Russia.

European scientists said Thursday that a new laboratory experiment shows the Earth's core is likely much hotter than last reported 20 years ago.

It's not that the iron core of our planet has warmed, but rather that the technique used to estimate its heat previously was flawed, researchers said in the journal Science.

Scientists at the world's biggest atom smasher have found further reasons for the apparent lack of antimatter in the universe.

A team working with data from CERN's Large Hadron Collider says it has discovered a particle that decays unevenly into matter and antimatter.

The discovery of the DNA double helix 60 years ago proved to be a headache for the Nobel organisation as the feat became nominated for prizes in different categories at the same time, Nature reported on Wednesday.

Francis Crick and Maurice Wilkins of Britain and James Watson of the United States shared the Nobel Prize for Medicine in 1962, nine years after revealing that the code for life has a spiral-staircase structure joined by chemical rungs.

An unmanned Russian spaceship carrying 2.5 tonnes of cargo may be unable to properly dock with the International Space Station after its navigation antenna failed to properly deploy, Interfax said on Thursday.

The news agency report cited a Russian space industry source as saying that the Progress cargo carrier may be impeded in its docking operation by the improperly protruding antenna.

The government of the Pacific paradise of New Caledonia said Wednesday it had decided to ban fishing of sharks, which are being decimated to feed growing demand for luxury goods.

"New Caledonia took the decision to ban the fishing, capture, detention or commercialization of all species of sharks" in its exclusive economic zone (EEZ) -- an area roughly the size of South Africa, authorities in the French territory said.

Six activists from conservation group Greenpeace boarded a coal carrier on the edge of the Great Barrier Reef Wednesday, calling for an end to exports of the fuel.

The group, from five major coal exporting and consuming nations in Asia-Pacific that are being targeted by Greenpeace, sailed out to the MV Meister to stage a protest on the bow urging an end to the "Age of Coal".

The cheetah, the world's fastest land animal, survived mass extinction during the last ice age 10,000 years ago.

But it has taken just the last few decades for man to place the hunter on the endangered species list, with experts warning it could disappear from the wild by 2030.

Australia was first settled by between 1,000 and 3,000 humans around 50,000 years ago, but the population crashed during the Ice Age before recovering to a peak of some 1.2 million people around five centuries ago, a study said on Wednesday.

Estimating the early population of Australia is a source of debate in anthropology, partly because it touches on how European colonization affected the country's indigenous people.