Who says solar power can't supply energy at night?

The team behind the Solar Impulse project - a mission to fly around the world in a plane powered only by the sun - has revealed the plane in which the pilots will make their attempt. 

Its predecessor, Solar Impulse 1, has already been flown across America, and stored sufficient power in its batteries to fly all night.

With a wingspan of 72m (236ft), Solar Impulse 2 is the wider than a Boeing 747, but weighs about the same as a large car.

Its wings are covered in 18,000 solar cells to convert sunlight into electricity to power its motor and to store in its batteries. Here's a link to the story and a fun quote. 

"I mean, the airplane can fly a month. The question is, What can the pilot do?" 

"So we have a sustainable airplane in terms of energy; we need to develop a sustainable pilot now."