Switzerland's Solar Impulse 2 landed late on Tuesday in the Chinese city of Nanjing, finishing the sixth stage of its landmark 12-leg quest to circumnavigate the globe powered only by the sun.

With pilot Bertrand Piccard at the controls, the pioneering single-seater aircraft touched down at 11:31pm local time, after a 17-hour trip from the southwestern megacity of Chongqing some 1,190 kilometres away.
   
Its arrival came after repeated meteorological delays and its other Swiss co-pilot, André Borschberg, returned to Europe to be treated for migraines.
   
Borschberg is expected to return to China by Friday, a Solar Impulse 2 spokesperson told AFP Tuesday.
   
"Wishing good health recovery to my friend (André Borschberg)," Piccard said in a Twitter message sent Tuesday morning as he flew high above China's Yangtze River.

"He should have flown this leg."
   
Borschberg tweeted back with a photo of Piccard in the cockpit and a message that the pilot — clad in an orange flight suit, blue air mask and dark sunglasses — was "looking great after more than ten hours of flight".

Piccard also posted to social media one of the more unusual selfies, taken from the cockpit of the solar aircraft: