American astronaut Scott Kelly has launched a geography quiz on Twitter and will post a picture from the International Space Station each week so fans can guess his location.

Kelly is spending one year in space along with Russian cosmonaut Mikhail Kornienko, in an experiment to see how the human mind and body withstands long periods in space, before even longer missions to Mars in the coming decades.

The thawing of the polar ice promises Arctic nations new opportunities to open ocean trade routes and offshore oil fields.

But the chill in relations between Western powers and their Arctic neighbor Russia could make the North a frontline in a new Cold War.

Australia Thursday said its plan to pay polluters to reduce carbon emissions blamed for climate change was off to a good start and would help the nation become a "world leader" in meeting pledges to tackle greenhouse gases.

The conservative government axed a controversial tax on greenhouse gas emissions last year as part of an election pledge, replacing it with a so-called "direct action" plan that included paying companies to increase energy efficiency and not pollute.

The National Zoo in Washington is hoping to get its giant panda Mei Xiang pregnant this spring after taking delivery of frozen panda semen from China for the first time.

Caitlin Burrell of the Smithsonian Conservation Biology Institute returned to the U.S. capital on Sunday with semen that had been stored at the Bifengxia Giant Panda Base in southwest China.

A group of top international experts on Wednesday urged governments to stick to their promises to combat climate change and said the aim should be to create a "zero-carbon society" by 2050.

To coincide with Earth Day, research institute The Earth League published a statement warning that 2015 would be "a critical year for humanity" ahead of a global warming summit in Paris in December.

Miami Beach's condo boom is bubbling hot, with glass towers being built as fast as they can be -- even as scientists say rising seas could swamp much of the storied city by the century's end.

City officials are betting that a property boom-fueled surge in real estate tax dollars will bankroll big investments in fighting effects of climate change.

As the Hubble Space Telescope celebrates 25 years in space this week, NASA and its international partners are building an even more powerful tool to look deeper into the universe than ever before.

The James Webb Space Telescope will be 100 times more potent than Hubble, and will launch in 2018 on a mission to give astronomers an unprecedented glimpse at the first galaxies that formed in the early universe.

A pioneering plane attempting to circumnavigate the globe powered only by the sun took off in China early Tuesday for the next stage of its journey, organizers said.

The Solar Impulse 2's departure from Chongqing came after repeated meteorological delays and one of its co-pilots returned to Europe to be treated for migraine.

The world's first space-based optical telescope marks its 25th anniversary this week. Here are some facts about the Hubble Space Telescope.

The telescope launched aboard the Space Shuttle Discovery in 1990 and is named after U.S. astronomer Edwin Hubble (1889-1953).

Air pollution levels in some of China's smoggiest cities fell by nearly a third in the first quarter of this year, environmental campaign group Greenpeace said on Tuesday.

But pollution levels remain a major public health threat, linked to thousands of early deaths, and the group said they continue to increase in other parts of the country.