<p>The <i>Solar Impulse 2</i> prepares to fly from California to Arizona on Monday, the first flight over North America in the historic trip around the world.</p>

The Solar Impulse 2 prepares to fly from California to Arizona on Monday, the first flight over North America in the historic trip around the world.

Photograph by Solar Impulse

16 Pictures From an Epic Solar Flight Around the World

See the Solar Impulse 2's attempt to make history and promote solar power.

The Solar Impulse 2 is another step closer to completing a historic trip around the world, all on solar power. The experimental craft landed in Phoenix, Arizona, Tuesday morning, after flying nearly 16 hours from Mountain View, California.

The voyage was the plane's first over North America, echoing the team's experimental flights with the previous Solar Impulse 1 in 2013. The plane landed in California on April 24 after flying thousands of miles from Hawaii. The most arduous and dangerous legs of the journey are now in the pilots' rearview mirrors.

(Read more about the genesis of the project, learn how the pilots cope with the tough flights, or see more photos of the quest.)

The team spent months out of the limelight in Hawaii, repairing damaged batteries and waiting for favorable weather to resume the epic voyage. The alternating pilots at the controls are Swiss adventurers Bertrand Piccard and André Borschberg.

We thought this was a good time to visit key moments from the effort, so we put together some of our favorite pictures of the project.

The goal, the team says, is to promote renewable energy and raise awareness for a cleaner, greener world. This story was originally published on April 26 and updated on May 3.

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