Imagine being able to use energy from the sun all the time, even when it's night. That's the idea that scientists at Caltech（California Institute of Technology）are exploring. They're working on collecting sunlight in space and sending its energy to Earth.

Caltech's scientists have created a special tool for this project. They call it MAPLE. MAPLE and two other devices are part of a project that was sent into space in January,

2023. MAPLE's job is to test the idea of sending energy wirelessly from space to Earth. We're used to using wires to move electrical energy from one place to another. But sending energy without wires is a lot trickier.

The method used by Caltech's scientists depends on the way waves act when they meet. Imagine two waves coming together as they travel in the same direction. If the tops of the waves line up, they combine to make a bigger wave. But if the top of one wave lines up with the low point of the other, the waves cancel each other out. The Caltech team has found a way to control the timing of lots of microwaves so that they can combine their power, and focus the energy in one direction. It's a little like using a magnifying（放大的）glass to focus sunlight into a small, hot point of light.

To prove that the system could work, MAPLE sent energy to two devices just 30 centimeters away in space. This energy was then turned into electricity, which made two small lights light up. Next, MAPLE sent energy all the way down to a lab at Caltech. The scientists were able to detect the energy, proving that it's possible to send solar energy to Earth from space.

Dr. Hajimiri, one of the project's leaders, thinks that one day, the system could be extremely useful, bringing energy to places that need it, all over the world. He believes that in the future, we'll be able to send energy to remote regions and areas destroyed by war or natural disaster.

What Is Your Next Destination?

Taste Tea in China

One of the oldest cultural landscapes in China is chosen to become one of the country's newest UNESCO World Heritage sites in 2022. The Ancient Tea Plantations of Jingmai Mountain in Pu'er features about 1.13 million tea trees. Located in China's Yunnan Province, the region was a sating point of the legendary Ancient Tea Horse Road. Many of the region's tea plantations remain, as do the four local ethnic minority groups — the Blang, Dai, Hani, and Wa people — who preserve their own languages, customs, and festivals.

Dive Deep in Palau

When you arrive here, the stamp in your passport will include the Palau Pledge (誓约), which all visitors must sign, promising that “the only footprints I shall leave are those that will wash away.” The eco-pledge was drafted by and for the children of these remote western Pacific islands to help preserve Palau's culture and environment from the negative impacts of tourism. Eighty percent of the nation's waters is preserved as the Palau National Marine Sanctuary.

Run Wild in Australia

Green shoots of regeneration are appearing in Australia, of which some 72,000 square miles were, burned during the 2019-2020 bushfires, leading to the deaths of nearly three dozen people and more than a billion animals. Drive the Great Ocean Road, in Victoria's Otways region, and then take a hike at Wildlife Wonders, an educational ancient forest and waterfalls. Wandering through bushes gives a chance to spot koalas unique to this ecosystem.

Go Green in Germany

Mining and steel production once dominated the crowded Ruhr Valley, in Germany's western state of North Rhine-Westphalia. Today, the region is repurposing previous industrial sites as parks and open air cultural spaces. The most famous is the UNESCO Word Heritage site of Zeche Zollverein, now home to an outdoor swimming pool, ice rink, and walking tails. You can rent a bike in Essen for a car-free Ruhr Valley trip along cycling routes.

The flashing green, red and purple curtains of the northern and southern lights—the auroras (极光) — may be the best-known phenomena lighting up the nighttime sky, but the most mysterious are the mauve (深紫色) and white streaks called Steve and their frequent companion, a shinning green "picket fence (尖桩栅栏)". 

First recognized in 2018 as distinct from the common auroras, Steve — a tongue-in-cheek reference to the mild name given a scary quick-fence in a 2006 children's movie — and its associated picket fence were nevertheless thought to be caused by the same physical processes. But scientists were left scratching their heads about how these shiny things were produced. 

Claire Gasque, a University of California, Berkeley, graduate student in physics, has now proposed a physical explanation for these phenomena that is totally different from the processes responsible for the well-known auroras. 

Red — blooded auroras and shinning phenomena such as Steve and the picket fence are becoming more common as the Sun enters the active period of its 11-year cycle, and November was a good month for Steve observations in the northern latitudes. Because all these short-lived shinning phenomena are caused by solar storms and coronal (日冕的) mass cast from the sun, the approaching solar maximum is an ideal time to study rare events like Steve and the picket fence. 

Gasque described the physics behind the picket fence in a paper published last month in the journal Geophysical Research Letters. She calculated that in a region of the upper atmosphere farther south than that in which auroras form, electric fields parallel to Earth's magnetic (磁的) field could produce the color spectrum of the picket fence, If correct, this unusual process has implications for how physicists understand energy flow between Earth's magnetosphere, which surrounds and protects Earth from the solar wind, and the ionosphere at the edge of space. 

"This would upend our modeling of what creates light and the energy in the aurora in some cases. It's really cool," she said, "It's one of the biggest mysteries in space physics right now."