Ghanaian college students plan Wednesday to launch a model of a satellite the size of a Coke can 200 yards (meters) into the air.

Organizers hope that it will be the start of this West African country's space program.

Scientists said Tuesday they have found a way to extract gold from ore using a seemingly unlikely pantry item -- cornstarch.

Traditional leaching employs poisonous cyanide to dissolve and extract the gold locked up in mineral ore -- but the method is polluting and controversial.

Researchers trying to explain declining elk numbers in the Yellowstone National Park (YNP) placed part of the blame Wednesday on a previously unlinked phenomenon -- a predatory trout invasion.

In a vicious circle of human interference that underscores the delicate balance of nature, the team said the illegal introduction of lake trout more than 20 years ago changed the diet of a key Yellowstone predator -- the grizzly bear.

Indonesia has extended a logging ban aimed at protecting rainforest despite fierce industry pressure, the government said Wednesday, although green groups say the move still does not go far enough.

Vast tracts of the sprawling Indonesian archipelago are covered in trees, including some of the world's most biodiverse tropical rainforest that is home to endangered animals such as orangutans, tigers and elephants.

The sun has fired off a massive flare, the strongest solar eruption this year.

The powerful flare occurred Sunday and erupted on the side of the sun that was not facing Earth. While the planet was not hit with radiation, space weather forecasters say the solar blast briefly disrupted high-frequency radio signals.

The hordes are rising. A cicada invasion is imminent in the U.S., with millions of the large cricket-like insects poised to emerge from the earth after 17 years lying in wait.

The first of the bugs that are expected to blanket the U.S. east coast have already been spotted in North Carolina and New Jersey.

Canadian spaceman Chris Hadfield on Tuesday returned to Earth along with two other astronauts after a half-year mission to the International Space Station that saw him become a global celebrity through his Twitter microblog.

Hadfield landed safely in the Kazakh steppe along with American Tom Marshburn and Russian Roman Romanenko aboard a Russian Soyuz-TMA capsule that had left the space station earlier Tuesday morning, mission control said.

The world has entered a "new danger zone" with levels of Earth-warming carbon dioxide in the atmosphere never experienced by humankind, the U.N.'s climate chief warned Monday.

When it breached the CO2 threshold of 400 parts per million (ppm) last week, the world "crossed an historic threshold and entered a new danger zone," Christiana Figueres said in a statement urging policy action.

A domestic natural gas boom already has lowered U.S. energy prices while stoking fears of environmental disaster. Now U.S. producers are poised to ship vast quantities of gas overseas as energy companies seek permits for proposed export projects that could set off a renewed frenzy of the much-debated kind of drilling known as fracking.

Expanded drilling is unlocking enormous reserves of crude oil and natural gas, offering the potential of moving the country closer to its decades-long quest for energy independence. Yet as the industry looks to profit from foreign markets, there is the specter of higher prices at home and increased manufacturing costs for products from plastics to fertilizers.

British billionaire Richard Branson said Monday that rocket-powered space tourism flights by his firm Virgin Galactic would have only a minor impact on climate change.

More than 500 people have already reserved seats -- and paid deposits on the $200,000 ticket price -- for a minutes-long suborbital flight on the SpaceShipTwo (SS2) set to begin by the end of this year.