photosphere

American  

[foh-tuh-sfeer] / ˈfoʊ təˌsfɪər /

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.

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photosphere British  

/ ˌfəʊtəʊˈsfɛrɪk, ˈfəʊtəʊˌsfɪə /

noun

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

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photosphere Scientific  

/ 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.

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Other Word Forms

Derived Forms

• photospheric
  adjective

Etymology

Origin of photosphere

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

Example Sentences

The dazzling luminous envelope which indicates to the naked eye the boundary of the solar disc is called the Photosphere.

From The Astronomy of Milton's 'Paradise Lost' by Orchard, Thomas Nathaniel

Photosphere, name given to the luminous atmosphere enveloping the sun.

From The Nuttall Encyclopædia Being a Concise and Comprehensive Dictionary of General Knowledge by Nuttall, P. Austin

This white bright portion is called the Photosphere.

From Astronomy of To-day A Popular Introduction in Non-Technical Language by Dolmage, Cecil Goodrich Julius

Photosphere, fō′tō-sfēr, n. the luminous envelope round the sun's globe, which is the source of light.

From Chambers's Twentieth Century Dictionary (part 3 of 4: N-R) by Various