photosphere

[ foh-tuh-sfeer ]

noun

1. a sphere of light or radiance.
2. Astronomy. the luminous visible surface of the sun, being a shallow layer of strongly ionized gases.

photosphere

/ ˌfəʊtəʊˈsfɛrɪk; ˈfəʊtəʊˌsfɪə /

noun

1. the visible surface of the sun, several hundred kilometres thick

photosphere

/ fō′tə-sfîr′ /

1. The lowest visible layer of a star, lying beneath the chromosphere and the corona. Stars are made entirely of gas and thus have no surface per se, but the gas beneath the photosphere is opaque, so the photosphere acts as their effective visible surface; it is also the boundary from which the Sun's diameter is measured. The Sun's photosphere is a very thin layer made up of numerous granules (transient convective cells) where hot gases rise and give off light and heat. The photosphere of the Sun has a temperature of around 6,000°K and is the region in which sunspot activity is located.

Derived Forms

• photospheric, adjective

Other Words From

• pho·to·spher·ic [foh-t, uh, -, sfer, -ik, -, sfeer, -], adjective

Word History and Origins

Origin of photosphere¹

First recorded in 1655–65; photo- + -sphere

Example Sentences

And last month the agency released the first-ever full-disk images of the Sun in wavelengths ranging from 200 to 400 nanometres, saying they provided "insights into the intricate details of the Sun's photosphere and chromosphere".

From BBC

The spacecraft is equipped with seven payloads to study the sun’s corona, chromosphere, photosphere and solar wind, the Indian Space Research Organization said.

From Seattle Times

“Then the photosphere cooled,” Dr. Montargès noted, “probably in the initially bright region that ejected the clump.”

From New York Times

During such an eclipse, the black silhouette of the moon — too far from Earth to completely cover the sun — will be surrounded by a thin ring of our home star’s surface, or photosphere.

From New York Times

But the reality is that the cosmos changes all the time, and so the properties of the cosmic photosphere—the original source of the microwave background originated, vary as well.

From Scientific American