"That day, we were almost in mourning," said Luc Bagalwa, a geophysics researcher in the eastern Democratic Republic of Congo, recalling the 2002 eruption of the Nyiragongo volcano.

While the ash and deep lava destroyed part of the northeastern city of Goma and prompted the evacuation of hundreds of thousands of people, the recording apparatus in Bagalwa's laboratory had no paper to note the spectacular seismic events.

At first sight the Salton Sea looks putrid, with dead fish scattered among patches of fetid water in a vast salty lake in the middle of the Californian desert. 

In the fourth year of a historic drought in the western United States, some say the wetland is an environmental time bomb.

Hundreds of kilometers below on Earth, their governments are locked in a standoff over Ukraine -- but up in space, Russian cosmonauts and American astronauts are still working together side by side.

The International Space Station (ISS) is one of the rare areas of U.S.-Russian cooperation that has not been hit by the Ukraine crisis and in the latest show of commitment, the next joint mission is set to blast off from Kazakhstan on Friday.

Russia officials say they will resume space tourism in 2018 after years of sending into space only professional cosmonauts and astronauts.

Russia had sent seven paying guests to the International Space Station since 2001 before curtailing the program in 2009. Sending a tourist has been all but impossible since 2011 when the United States shut down its Space Shuttle program and had to rely on Russian Soyuz rockets in order to get into orbit.

NASA's Curiosity rover has found nitrogen on the surface of Mars, a significant discovery that adds to evidence the Red Planet could once have sustained life, the space agency said Tuesday.

By drilling into Martian rocks, Curiosity found evidence of nitrates, compounds containing nitrogen that can be used by living organisms.

Workers at a Tokyo aquarium are scratching their heads after the deaths of dozens of fish that have left just one lonely tuna roaming a once-flourishing tank.

The park on Tuesday found the second last fish floating dead in its vast doughnut-shaped enclosure that was once home to nearly 160 fish and among the venue's most popular attractions, said a spokesman for Tokyo Sea Life Park.

India's famously frugal Mars mission has been extended by around six months thanks to a surplus of fuel on board the spacecraft, the country's space agency said Tuesday.

The Mars Orbiter Mission spacecraft had been scheduled to wrap up its mission this month after India in September became the first Asian nation to reach the Red Planet, all on a shoe-string budget.

Scientists in Portugal have uncovered the fossils of a previously unknown crocodile-like creature that was among the Earth's top predators more than 200 million years ago.

The remains found on the site of an ancient lake suggest the creature was like a giant salamander, according to a study released Monday.

Human feces contains gold and other precious metals that could be worth hundreds of millions of dollars, experts say.

Now the trick is how to retrieve them -- a potential windfall that could also help save the planet. 

African elephants could be extinct in the wild within a few decades, experts warned on Monday at a major conservation summit in Botswana that highlighted an alarming decline in numbers due to poaching.

The Africa Elephant Summit, held at a tourist resort in Kasane, gathered delegates from about 20 countries across Europe, Africa and Asia, including China -- which is accused of fuelling the illegal poaching trade.