Solar Impulse Pilot Snaps an Extreme Selfie Upon Crossing US

— -- Solar Impulse pilot Bertrand Piccard snapped a sky-high selfie as he cruised toward Pennsylvania during the 13th leg of the plane's journey around the world.

The Swiss adventurer was able to memorialize his time in the cockpit by using what appears to be an extremely long selfie stick held outside the window of the solar-powered plane.

Piccard and Andre Borschberg have been taking turns flying the one-seater airplane, which is solely powered by the sun's energy.

The final American leg will include Borschberg flying from Pennsylvania and past the Statue of Liberty before landing in New York ahead of a grueling transatlantic flight.

Solar Impulse tends to take at least a few days at each stop to hold events and give the pilots time to switch off before the next leg.

Solar Impulse is able to fly day and night because of the solar energy is stored in batteries on the aircraft. The duo expect to complete their around-the-world journey this summer in Abu Dhabi. While the project is designed to raise awareness about clean energy, it's also provided some memorable personal moments.

Piccard, who spoke with ABC News from the cockpit of Solar Impulse on Wednesday, said his most memorable moment thus far as an explorer was when he was crossing the Pacific Ocean between Hawaii and San Francisco.

"I was in the middle of the ocean, in the middle of the night, alone in the plane and I was just really happy because this is the world I love," he said. "This is the world of exploration. You get out of your comfort zone, you explore the unknown. You are pushing the limits and you discover what you have inside of yourself."