KAPOLEI, Hawaii: A 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 early Friday — Earth Day — an occasion the team planned to mark with a live call between pilot Bertrand Piccard and Secretary-General Ban Ki-moon, according to the website that’s documenting the journey of Solar Impulse 2.

After some uncertainty about winds, the plane took off from Hawaii Thursday morning and was on course to land in Mountain View, California, over the weekend. The crew that helped it take off was clearing out of its Hawaiian hangar and headed for the mainland for the weekend arrival.

“We have passed the point of no return,” the team wrote on the website. “From this point onwards, Bertrand Piccard will only be moving forward with Si2.”

At one point passengers on a Hawaiian Air jet caught a glimpse of the Solar Impulse 2 before the powerful airliner sped past the slow-moving aircraft.

The Solar Impulse 2 landed in Hawaii in July and was forced to stay in the islands after the plane’s battery system sustained heat damage on its trip from Japan. The aircraft started its around-the-world journey in March 2015 from Abu Dhabi and made stops in Oman, Myanmar, China and Japan. It’s on the ninth leg of its circumnavigation.