"Each balloon is 15m (49.2ft) in diameter - the length of a small plane - and filled with lifting gases. Electronic equipment hangs underneath including radio antennas, a flight computer, an altitude control system and solar panels to power the gear.
Google aims to fly the balloons in the stratosphere, 20km (12 miles) or more above the ground, which is about double the altitude used by commercial aircraft and above controlled airspace.
Google says each should stay aloft for about 100 days and provide connectivity to an area stretching 40km in diameter below as they travel in a west-to-east direction."
"It says that balloons could one day be diverted to disaster-hit areas to aid rescue efforts in situations where ground communication equipment has been damaged."