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Triquetrum of Copernicus

An engraving of the wooden triquetrum, a parallactic instrument Copernicus used for astronomical observations.

An instrument Copernicus owned and used for his astronomical observations, later prized by Tycho Brahe.

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Black and white engraving of a brass astronomical instrument on a round base, with three long graduated rods labeled A, B, C, and D pivoted together, mounted on a vertical post. A small wooden box with a sighting opening sits on a table to the left.
Triquetrum (Dreistab) of Nicolaus Copernicus. Engraving.

About this source

What it is

This is an engraving showing a triquetrum, a simple instrument made of jointed graduated rods used to measure the angle of celestial bodies. It belonged to Nicolaus Copernicus and was later owned and prized by the astronomer Tycho Brahe.

Why it matters

The instrument shows how basic the tools of pre-telescope astronomy were. Copernicus made his observations with devices like this one, built from wood and simple materials, yet from them he developed a new model of the universe. That the instrument was later kept by Tycho Brahe, another major astronomer, shows how valued Copernicus's tools became after his death.

Look closer

  • What can you tell about how the instrument worked just from looking at its parts?
  • Why might later astronomers like Tycho Brahe have wanted to keep Copernicus's own instrument?
  • What does the simplicity of this tool suggest about the limits of observation in Copernicus's time?

This artifact is part of the curated material that grounds the AI version of Nicolaus Copernicus on Humy.ai — when students ask about related events, the AI can quote it and cite it.

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Title page of Nicolaus Copernicus's De revolutionibus orbium coelestium, printed 1543 in Nuremberg by Johann Petreius. Large capitals read NICOLAI COPERNICI TORINENSIS, followed by the book title and an address to the reader in Latin. Handwritten ink marks read Bibliotheca and Univers, and a Greek motto appears below the text.Book

Primary source

De revolutionibus orbium coelestium

Nicolaus Copernicus · 1543

Engraved portrait print of Nicolaus Copernicus in an octagonal frame with stippled background. A man with wavy shoulder-length hair wears a fur-trimmed garment and holds a small armillary-style sphere. Caption reads NICOLAUS COPERNICUS, with publisher line Zwickau, bei Gebr. Schumann below.Painting

Secondary source

Portrait of Nicolaus Copernicus (Schumann print)

Gebrüder Schumann

Scanned page from a 1543 printed book titled Nicolai Copernici, showing a diagram of concentric circles with the Sun at the center, labeled planetary orbits including Mercury, Venus, Earth (terra) with the Moon, Mars, Jupiter, Saturn, and the outer sphere of fixed stars. Latin text surrounds the diagram.Artifact

Primary source

Copernicus's Diagram of the Planetary System

Nicolaus Copernicus · 1543

Engraved oval portrait of Nicolaus Copernicus, a man with wavy shoulder-length hair and a fur-collared garment, inside a decorative border with Latin inscriptions and dates, on a book page photographed on a dark background with a gray scale.Painting

Secondary source

Engraved Portrait of Nicolaus Copernicus (Herzog August Library)

Unbekannt

Engraved portrait of Nicolaus Copernicus in an oval frame, shown on a book page with a page number 52 in the corner. The man has curly hair and wears a fur-trimmed garment. Latin inscription 'NICOLAUS COPERNICUS' appears at the bottom, with a verse text block below and a catalogue number beneath the page.Painting

Secondary source

Portrait of Nicolaus Copernicus (Albertina Museum)

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