Rotation
circular movement of an object around a center or axis of rotation
Rotation, also known as rotational motion or rotary motion, is the movement of an object that leaves at least one point unchanged. In 2 dimensions, a plane figure can rotate in either a clockwise or counterclockwise sense around a point called the center of rotation. In 3 dimensions, a solid figure rotates around an imaginary line called an axis of rotation.
The special case of a rotation with an internal axis passing through the body's own center of mass is known as a spin (or autorotation). In that case, the surface intersection of the internal spin axis can be called a pole; for example, Earth's rotation defines the geographical poles.
A rotation around an axis completely external to the moving body is called a revolution (or orbit), as in a planetary orbit, e.g., Earth's orbit around the Sun. The ends of the external axis of revolution can be called the orbital poles.
Either type of rotation is involved in a corresponding type of angular velocity (spin angular velocity and orbital angular velocity) and angular momentum (spin angular momentum and orbital angular momentum).
Mathematics
Mathematically, a rotation is a rigid body movement which, unlike a translation, keeps at least one point fixed. This definition applies to rotations in two dimensions (in a plane), in which exactly one point is kept fixed; and also in three dimensions (in space), in which additional points may be kept fixed (as in rotation around a fixed axis, as infinite line).
The public source identifies “Rotation” as circular movement of an object around a center or axis of rotation. This brief keeps that definition visible, then builds a research path around Rotation, circular and movement.
Why this record matters
A short description can identify a subject without explaining its stakes. For “Rotation”, the useful work is to connect “circular movement of an object around a center or axis of rotation” to the records capable of establishing context and consequence.
Contemporary correspondence, administrative files and participant testimony can test how later narratives organized the event or institution. The source revision retrieved here is dated Jul 4, 2026. The linked authority identifier is Q107617. The Library of Congress control number is sh85115493. 1 of 1 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank.
Later summaries often reconcile disputed chronology or motive more neatly than the contemporary record permits. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Compare institutional narratives with records created by participants and affected communities. Dates and formal titles are useful anchors, but not substitutes for context.
- Event chronology
- Institutional context
- Locating named record creators
Contemporary correspondence, government or organizational records, oral histories and cited historical scholarship.
Three-step research path
- Establish the record: confirm the title “Rotation”, its source revision and the description used here.
- Expand the search: follow Rotation primary sources, Rotation archive and Rotation research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Rotation”?
- Which voices are present, absent or mediated by the institution?
- What chronology connects this entry to wider political or social change?
Search terms from this dossier
This entry incorporates text from “Rotation” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.