# Planisphaerium presents stereographic projection as a public instrument-text

Date: 150

## The fact

Planisphaerium presents stereographic projection of the celestial sphere. [Ptolemy](/people/ptolemy)’s documented role is: He wrote on stereographic projection, a basis for the later astrolabe. Later Latin from Arabic is the public carrier; he did not typeset it. Do not twin this with Geography longitude-stretch. A projection treatise is not a gazetteer’s error-heading. Later editors, printers, and excavators remain named where they appear. Ptolemy's documented role is: He wrote on stereographic projection, a basis for the later astrolabe. Later Latin from Arabic is the public carrier; he did not typeset it.

## Context

A mathematical instrument tradition, unnamed copyists, and later astrolabe-makers already sit in the file. A projection is not unique authorship of every later brass astrolabe. Later Latin is access. Named others on the file: Unnamed copyists, later astrolabe-makers, and Arabic-Latin translators share the treatise’s survival. The public setting is the file around 0150-08-01. Unnamed clerks, soldiers, printers, or later editors may appear without becoming this instrument. The instrument stays Planisphaerium presents stereographic projection as a public instrument-text. The setting of Planisphaerium presents stereographic projection as a public instrument-text is the public file around 0150-08-01. Shared offices, unnamed crews, printers, or later editors may appear without becoming this instrument. Driver edu-[digital-learning-access](/drivers/edu-digital-learning-access) is attached because the significance names a mechanism from this act, not because a standing list needed coverage.

## Evidence and sources

Britannica independently identifies Planisphaerium as a distinct Ptolemaic projection text. Official: Britannica — Ptolemy, Planisphaerium (https://www.britannica.com/biography/Ptolemy; Encyclopaedia Britannica). Independent: Britannica — astrolabe, Ptolemaic projection heritage (https://www.britannica.com/science/astrolabe-instrument; Encyclopaedia Britannica). The two URLs are different pages. Where the carrier is a later edition or a received narrative, that limit is stated rather than upgraded to an autograph. Official carrier: Britannica — Ptolemy, Planisphaerium (https://www.britannica.com/biography/Ptolemy; Encyclopaedia Britannica). Independent carrier: Britannica — astrolabe, Ptolemaic projection heritage (https://www.britannica.com/science/astrolabe-instrument; Encyclopaedia Britannica).

Official or archival record: Britannica — Ptolemy, Planisphaerium (https://www.britannica.com/biography/Ptolemy; Encyclopaedia Britannica).

## Significance

Improving education-access path: a public stereographic-projection treatise. Complex later carrier. Welfare reading improving. The attached mechanism is A dated projection-treatise put a public mapping of the sphere onto a plane into the instrument file, distinct from Geography’s longitude-stretch heading. Lag to any modern indicator is not treated as zero. This path is attached because the mechanism is named from this act, not because a driver list needed coverage. The welfare reading on this path is improving.

If a number is not in the two records named above, it is not supplied here.

## What is established and what is not

Established: Planisphaerium as a Ptolemaic work. Not established: that Geography is this same book. Established: a sourced public record of Planisphaerium presents stereographic projection as a public instrument-text under 0150-08-01. Established: a sourced public record of Planisphaerium presents stereographic projection as a public instrument-text under 0150-08-01.

Confidence is stated on the impact path, not hidden in adjectives. Do not twin this with Geography longitude-stretch. A projection treatise is not a gazetteer’s error-heading. Mixed effects of Planisphaerium presents stereographic projection as a public instrument-text are separate paths.

Later competitions, monuments, translations, UNESCO listings, museums, and adaptations are not converted into extra lifetime acts.

The welfare reading used in this dossier is improving. That reading is an impact-path choice, not a property stored on the Fact itself.

Shared responsibility is part of Planisphaerium presents stereographic projection as a public instrument-text. Naming Ptolemy does not delete co-authors, institutions, or later transmitters. The lag from 0150-08-01 to any measured indicator is not treated as zero. Alternative explanations — weather, other armies, later statutes, or independent cultural change — remain live where the sources do not close them.

## People

- Ptolemy: https://factrail.ai/people/ptolemy

## Drivers

- Digital Learning Access: https://factrail.ai/drivers/edu-digital-learning-access

## Sources

- https://www.britannica.com/science/astrolabe-instrument
- https://www.britannica.com/biography/Ptolemy

## Methodology

https://factrail.ai/methodology

Canonical: https://factrail.ai/facts/pto-planisphaerium