The Solar Impulse, an aircraft that generates power solely from the sun's energy, is set to embark on the longest leg of its planned round-the-world journey: a trip of some 115 hours between Nagoya, Japan, and Hawaii. But weather concerns have forced another delay.

The Solar Impulse 2 had initially been slated to take off from Japan around 1:30 p.m. ET.

Update at 3 p.m. ET: Flight Is Postponed

After prolonged discussions about weather patterns in the solar-powered aircraft's flight path, the plane's flight team has decided to postpone the long trip to Hawaii.

Solar Impulse's Conor Lennon says that the weather window turned out to be "a little more complicated than expected."

Update at 1:51 p.m. ET: Takeoff Delayed

Citing concerns about the weather, the team behind the Solar Impulse aircraft has delayed its takeoff from Nagoya. They'll have to decide whether to scrub the takeoff soon, they say, before the sun rises in Japan and creates too much heat and wind on the tarmac for a safe takeoff.

This would be the second time the Nagoya-Hawaii leg of the journey has been postponed; a takeoff earlier this month was put off due to a strong weather front.

Our original post continues:

Since the Solar Impulse began its trip in March, it has flown to Abu Dhabi, India, and China. As we've reported, the aircraft's surface includes some 17,000 solar cells. It also has lithium-ion batteries that "account for about 1,400 of the craft's overall weight of some 5,000 pounds."

According to the flight's organizers:

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