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Published: 1st September 2021

Citation: Astronist Institution. (2021). Sideria. Available: Last accessed [enter date e.g. 1st Sept 2021].


noun  Astroeschatology

an end-time event believed by some schools of Astronism to involve the closing of humanity’s opportunity window for transcension and the subsequent deprivation and eventual extinction of human life thereafter.


Siderial | sʌɪˈ dɪərɪ(ə)l | adjective
Siderially | sʌɪˈ dɪərɪ(ə)li | adverb
Siderian | sʌɪˈ dɪərɪən | adjective


Astro-English: from Astronese, the word Sideria is based on the adjective sidereal which denotes “the distant stars” but is used here in a more general sense “to denote the astronomical world”; in the context of the Astroeschatology and with the addition of the suffix -ia denoting a condition, the word Sideria comes to mean “the instance of the closure of the scope window.”

Encyclopaedic entry for “Sideria” on

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