Sunlight

Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is filtered through Earth's atmosphere, and is obvious as daylight when the Sun is above the horizon. When the direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat. When it is blocked by the clouds or reflects off other objects, it is experienced as diffused light. The World Meteorological Organization uses the term "sunshine duration" to mean the cumulative time during which an area receives direct irradiance from the Sun of at least 120 watts per square meter.

The ultraviolet radiation in sunlight has both positive and negative health effects, as it is both a principal source of vitamin D₃ and a mutagen.

Summary

Researchers may record sunlight using a sunshine recorder, pyranometer, or pyrheliometer.

Sunlight takes about 8.3 minutes to reach Earth from the surface of the Sun. A photon starting at the centre of the Sun and changing direction every time it encounters a charged particle would take between 10,000 and 170,000 years to get to the surface.

Dragon

A dragon is a legendary creature, typically with serpentine or reptilian traits, that features in the myths of many cultures. There are two distinct cultural traditions of dragons: the European dragon, derived from European folk traditions and ultimately related to Greek and Middle Eastern mythologies, and the Chinese dragon, with counterparts in Japan (namely the Japanese dragon), Korea and other East Asian countries.

The two traditions may have evolved separately, but have influenced each other to a certain extent, particularly with the cross-cultural contact of recent centuries. The English word dragon derives from Greek δράκων (drákōn), "dragon, serpent of huge size, water-snake".

Name

The word dragon entered the English language in the early 13th century from Old French dragon, which in turn comes from Latin draconem (nominative draco) meaning "huge serpent, dragon", from the Greek word δράκων, drakon (genitive drakontos, δράκοντος) "serpent, giant seafish". The Greek and Latin term referred to any great serpent, not necessarily mythological, and this usage was also current in English up to the 18th century.