Earthshine

Part of speech: noun

Pronunciation: /ˈɜː(ɹ)θʃaɪn/

Definitions

1. the faint illumination of the moon's dark side caused by sunlight reflecting off Earth's surface and atmosphere
2. a dim glow on the unlit portion of the lunar disk produced by light bounced from our planet
3. the subtle brightness visible on the shadowed face of the moon due to reflected solar radiation from Earth

Etymology: Earthshine is a compound noun formed from two common English words, each with its own straightforward history. "Earth" descends from Old English "eorthe," which is inherited from Proto-Germanic "erthō," ultimately deriving from the Proto-Indo-European root "er-" meaning "to move" or "to stir." The word has been in continuous use in English since the earliest recorded texts, referring to the ground or soil, and later to the planet itself. "Shine" comes from Old English "scinan," also from Proto-Germanic "skinaną," and originally meant "to emit light" or "to be bright." Both words are native to English rather than borrowed from Romance languages. The compound "earthshine" itself is a modern astronomical term, likely coined in the 19th or 20th century as telescopic observation of the Moon became more refined and systematic. It refers specifically to the faint illumination of the Moon's dark portion caused by sunlight reflected from Earth's surface and atmosphere—the phenomenon sometimes called the "old Moon in the new Moon's arms." The term is descriptive and transparent: it names the shine or glow that comes from Earth itself, cast upon the Moon. Unlike many technical astronomical terms, which are assembled from Greek or Latin roots, earthshine is constructed entirely from native English vocabulary, making it immediately intelligible to English speakers without classical training.

Synonyms: planetshine