In this photo provided by Solar Impulse, the solar powered plane, "Solar Impulse 2," piloted by Bertrant Piccard of Switzerland, is seen in the air Thursday, April 21, 2016, after successfully taking off from Kalaeloa Airport, O'ahu, Hawaii, for a non-stop three day flight expected to cover about 3,760 kilometers (2,336 miles) to San Francisco. (Jean Revillard/Solar Impulse via AP)

The Latest on the flight of a solar-powered airplane from Hawaii to California in an attempt to circumnavigate the globe (all times local):

9:45 p.m.

The final leg of a solar-powered airplane's across the Pacific Ocean is going smoothly.

That's according to the project's website, which says the Solar Impulse 2 aircraft picked up a strong tail wind and is cruising at 150 kph, or about 93 mph. The website says that's considered fast for the plane.

Solar Impulse 2 is 36 hours into a three-day flight over the Pacific with solo pilot Bertrand Piccard at the controls.

The plane took off from Hawaii on Thursday morning and is expected to arrive in the San Francisco Bay Area by Saturday evening.

The aircraft started its around-the-world journey in March 2015 from Abu Dhabi, the capital of the United Arab Emirates, and made stops in Oman, Myanmar, China and Japan. It's on the ninth leg of its circumnavigation.

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5 p.m.

A solar-powered airplane has passed the halfway point for the final leg of its around-the-world journey as it flies high above the Pacific Ocean en route to a stop in Northern California.

The project's website says the Solar Impulse 2 aircraft is 32 hours into a three-day flight over the Pacific with solo pilot Bertrand Piccard at the controls.

In this Thursday, April 21, 2016 file photo, the Solar Impulse 2 solar plane lifts off at the Kalaeloa Airport, in Kapolei, Hawaii. The solar plane on an around-the-world journey has reached the point of no return over the Pacific Ocean after departing Hawaii, and now it's California or bust. The plane was cruising over the cold northern Pacific late Thursday at about 20,000 feet with a nearly-full battery as night descended, according to the website that's documenting the journey of Solar Impulse 2. (AP Photo/Marco Garcia, File)

The plane took off from Hawaii on Thursday morning and is expected to arrive in the San Francisco Bay area by Saturday evening.

The trans-Pacific leg of his journey is the riskiest part of the plane's global travels because of the lack of emergency landing sites.

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12:50 p.m.

The pilot of a solar-powered airplane on an around-the-world journey has received a midair greeting from United Nations Secretary-General Ban Ki-moon, who lauded him by phone for his historic journey.

In this Thursday, April 21, 2016 file photo, the Solar Impulse 2 solar plane flies out of the Kalaeloa Airport, in Kapolei, Hawaii. The solar plane on an around-the-world journey has reached the point of no return over the Pacific Ocean after departing Hawaii, and now it's California or bust. The plane was cruising over the cold northern Pacific late Thursday at about 20,000 feet with a nearly-full battery as night descended, according to the website that's documenting the journey of Solar Impulse 2. (AP Photo/Marco Garcia, File)

"I am inspired by your pioneering spirit," Ban told Solar Impulse 2's pilot, Bertrand Piccard, during a brief conversation streamed live on the aircraft's website.

Piccard told the secretary-general he, too, is making history by having just presided over the signing of a climate change agreement by representatives of 175 nations gathered at the U.N. in New York.

Piccard said his flight is showing that solar energy is the pathway to a future with reduced carbon emissions and a safer, cleaner planet Earth.

The pair spoke on Earth Day, as Piccard continued his journey from Hawaii to Northern California.

He told Ban he is about halfway there and expects to arrive in San Francisco on Saturday evening.

Solar Impulse 2 pilot Bertrand Piccard prepares to fly across the Pacific in a solar plane from Kalaeloa Airport, Thursday, April 21, 2016, in Kapolei, Hawaii. The solar plane will fly a two-and-a-half day journey to Northern California. (AP Photo/Marco Garcia)

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8:15 a.m.

A solar-powered airplane on an around-the-world journey is about a third of the way from Hawaii to California.

The project's website says the Solar Impulse 2 aircraft is nearly 23 hours into a three-day flight over the Pacific with solo pilot Bertrand Piccard at the controls.

A live image from the plane showed the first light of dawn on the horizon.

The aircraft's wings are covered with solar cells to take energy from the sun to power the motors turning its propellers. During darkness it relies on energy stored in batteries.

The aircraft's destination on this leg of the journey is Mountain View, California, at the southern end of San Francisco Bay.

The aircraft started its journey in March 2015 from Abu Dhabi, the capital of the United Arab Emirates, and made stops in Oman, Myanmar, China and Japan before reaching Hawaii.

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