The experimental plane called Solar Impulse 2 has taken off in Hawaii after a nine-month delay for repairs.
The team on the ground and at mission control let out exuberant cheers as the cutting-edge aircraft rose up into the early morning skies.
They're aiming to circumnavigate the globe using only the power of the sun.
During the previous leg — a five-day long journey from Japan to Hawaii — the plane's batteries overheated. As the Two-Way has reported, that leg broke the record for longest duration nonstop solo flight.
The Solar Impulse 2 team is broadcasting live. You can tune in here and follow the plane's journey over the Pacific:
They project it will take 62 hours for Solar Impulse 2 and pilot Bertrand Piccard to reach Moffett Federal Airfield in Mountain View, Calif. Piccard and pilot André Borschberg alternate legs of the journey around the world.
Even during the final hour before liftoff for the ninth leg of the journey, the team was weighing whether to fly today due to the weather conditions.
The aircraft doesn't handle well in gusty winds. It has "the wingspan of a Boeing 747, but weighs no more than a mid-sized car," the Two-Way reported earlier this month.
"We had some emotions by not knowing how the wind would turn out this morning. Happy to be on the runway," Borschberg said on the live video feed.
He added that at one stage, they were close to the limit, and explained how they handled it:
"We decided to move the airplane facing the wind, because the movement of the airplane when the wind comes from the side is very difficult and can be tricky, potentially dangerous. We used the strategy of keeping the aircraft always facing the wind like it will do for takeoff, because of course it's much easier to handle. It took a bit more time but was very safe, very good. I'm very happy."
The team hopes to fly around the world in 10 stages — starting the journey in Abu Dhabi and, if all goes well, ending there.
Solar Impulse 2 aims to promote clean energy. "We have built an experimental aircraft that we use to explore not only altitudes, but also unknown territories within the realm of clean technology and creative team building," the team said.