Mercury, the oddest of the rocky planets, has been little understood by scientists. But on a swing by the planet, NASA's Messenger sent back intriguing data about Mercury's surface minerals and volcanic activity.
Pittsburgh will show a green, high-tech face to its G-20 guests.
Topping the G-20 'to do' list is to settle on any additional economic stimulus – and whether to rein in banker bonuses. Global warming is on the table, too.
If the pattern continues, warming effects could reach up to 900 miles inland, melting permafrost