Image: Mirror array for LSS

The giant 121-segment mirror array used to reflect simulated sunlight into the largest vacuum chamber in Europe seen being hoisted into position within ESA's technical heart back in 1986.

New instrument unravels landscape longevity

How many years can a mountain exist? Bob Dylan's rhetorical question has just received yet another scientifically based answer. Researchers from Wageningen University & Research (WUR) and Denmark's Technical University (DTU) ...

Thermal testing of Solar Orbiter

A side view of ESA's Solar Orbiter as it entered a vacuum chamber for thermal vacuum testing at the IABG test facility in Ottobrunn, Germany, last month.

Evaluating the contribution of black carbon to climate change

Japanese and US researchers developed an advanced model to assess the ability of black carbon particles to absorb sunlight and contribute to global warming. The model achieved higher sensitivity than obtained by previous ...

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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