The solar-powered plane Solar Impulse 2 just made a historic trip across the Pacific

The Solar Impulse 2, a plane fueled only by solar panels, spent two days flying across the Pacific and landed triumphantly in California on Sunday, completing the latest leg of the first attempt to circumnavigate the world using only solar power.

It was a gorgeous landing:

Jean Revillard via Getty Images

The Solar Impulse 2 has had a long trip so far, even longer than you'd expect given that it travels just 43 miles per hour. The journey started in March 2015 in Abu Dhabi. In July, after delays and setbacks in Asia, the plane's batteries overheated during the most important stretch of its trip so far, the five-day journey from Japan to Hawaii. The plane and its two-person crew spent 10 months in Oahu repairing the aircraft.

Now that it's back in the air, the next step is to fly across the US, then the Atlantic, with a stop in southern Europe or northern Africa, before completing the loop in Abu Dhabi:

Solar Impulse

The goal of the journey, besides setting a new world record, is promoting clean energy. As Vox's Brad Plumer wrote when the plane took off in 2015, its slow speed and the fact that it can only hold two passengers means that solar-powered aircraft might not have many practical implications for air travel in the foreseeable future. (Biofuels, not solar power, are the aircraft industry's big hope for cutting emissions.)

But a plane as big as a Boeing 747 that carries only two people makes for a stunning sight as it lands:

One of the pilots comes from a long line of explorers

The flight of the Solar Impulse 2 feels like an old time adventure, or at least a steampunk one — a throwback to the early days of flight, when making it across the ocean was a harrowing feat.

One of the plane's two pilots, Bertrand Piccard, is a direct descendent of those earlier inventors, carrying on a family tradition of breaking records.

He's the grandson of Auguste Piccard, a Swiss physicist who took a hydrogen balloon to the stratosphere in 1931 — the highest a human being had ever traveled. (Auguste Piccard became the model for Professor Calculus in the Tintin comics, an absent-minded professor who invents spectacular devices.)

Then, in 1960, Auguste's son, Jacques Piccard, was the first person to explore the deepest part of the ocean, the Mariana Trench, in a capsule called a bathyscaphe that he had designed himself — going deeper than any human being before.

And Bertrand Piccard has already added his own record to the family's pile: He was the first to complete a nonstop air balloon flight around the world. If all goes well, he and his co-pilot, André Borschberg, will become the first to circumnavigate the world in a solar plane as well.

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