Solar-power satellites to collect stronger sunlight

Solar energy generation keeps on becoming cheaper and more efficient, but some basic limitations will always apply: solar panels can only generate power during the daytime, and much of the sunlight is absorbed by the atmosphere ...

Turning astronaut waste into fuel on Mars

To survive on Mars will mean maximizing use of all available resources. A team from Spanish technological center Tekniker is working on a system that uses sunlight to produce fuel from astronaut wastewater.

Sunlight could be used to power lasers

Sunlight, one of the planet's most abundant sources of renewable energy, could be used to power lasers, according to a study from Heriot-Watt University.

Image: Dedicated satellites to collect solar energy

Sunlight up in Earth orbit is 10 times more intense than down on Earth's surface, so the idea is to fly dedicated satellites to capture solar energy, then beam it down to Earth—and potentially the Moon or other planets ...

Modified silk cloth keeps skin cooler than cotton

A team of researchers affiliated with a host of entities in China and one in the U.S. has developed a modified textile that can keep skin cooler than materials made of cotton. In their paper published in the journal Nature ...

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Sunlight

Sunlight, in the broad sense, is the total spectrum of the electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the atmosphere, and the solar radiation is obvious as daylight when the Sun is above the horizon. Near the poles in summer, the days are longer and the nights are shorter or non-existent. In the winter at the poles the nights are longer and for some periods of time, sunlight may not occur at all. When the direct radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and heat. Radiant heat directly produced by the radiation of the sun is different from the increase in atmospheric temperature due to the radiative heating of the atmosphere by the sun's radiation. Sunlight may be recorded using a sunshine recorder, pyranometer or pyrheliometer. Sunlight takes about 8.3 minutes to reach the Earth. The World Meteorological Organization defines sunshine as direct irradiance from the Sun measured on the ground of at least 120 watts per square metre.

Direct sunlight has a luminous efficacy of about 93 lumens per watt of radiant flux, which includes infrared, visible, and ultra-violet light. Bright sunlight provides luminance of approximately 100,000 candela per square meter at the Earth's surface.

Sunlight is a key factor in photosynthesis, a process crucially important for life on Earth.

This text uses material from Wikipedia, licensed under CC BY-SA