In history's first ever fully solar-powered flight around the world, the Solar Impulse 2 took off from Hawaii on Friday heading towards California. Flown by Bertrand Piccard, the Solar Impulse 2 is now on its ninth leg to complete its global journey.

Along with the world's celebration of Earth Day, Piccard and his substitute pilot flew the Solar Impulse 2 now fly above the Pacific Ocean for the final and most perilous lap of the journey. This Trans-Pacific leg is considered the riskiest, as they fly above a place with no emergency landing sites.

Minutes before the flight, Piccard had a chance to talk with United Nations Secretary-General Ban Ki-moon, who summoned him and stated that he was making history with his inspirational pioneering spirit. The pilot responded by praising the secretary general for leading the 175 nations in signing the climate agreement.

"What you are doing today in New York, signing the Paris agreement, is more than protecting the environment, it is the launch of the clean technology revolution," said Piccard, according to ABC.

This 2,200 kilogram carbon-fibre aircraft ideally runs at a speed of 45 kilometres per hour which can double at daytime when the sun is shining strong. It is equipped with 17,000 solar cells powering the propellers and charging batteries which makes the plane run at night, as per CBC News.

The journey started March 2015 for Solar Impulse 2. It began in Abu Dhabi, making temporary landing in Oman, Myanmar, China and Japan. It had to stop in July after its trip from Japan to Hawaii when the plane's battery system has been damaged.

A damaged wing has been the cause of its delay in Asia on its to fly from China to Hawaii route. After a month of repair and as soon as the weather got better, the Solar Impulse 2 left Central Japan and headed for Hawaii.

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