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

• photospheric
  adjective

Etymology

Origin of photosphere

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

Example Sentences

See Examples For:

photosphere

The Sun's corona extends out for 10 million kilometres, and is a million times less intense than its surface, which is called the photosphere.

From Barron's ● Aug. 5, 2026

During normal times when there is no eclipse, scientists study the Sun's atmosphere with satellites equipped with a coronagraph -- "a filter that blocks out the photosphere", Brun explained.

From Barron's ● Aug. 5, 2026

Prof Ramesh says when we look at the Sun from the Earth, we see an orange ball of fire which is the photosphere - the Sun's surface or the brightest part of the star.

From BBC ● Nov. 26, 2024

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 ● Sep. 1, 2023

Of the more special appearances which the photosphere presents, let us take first the faculæ.

From Essays: Scientific, Political, & Speculative, Vol. I by Herbert Spencer