Orange peels and Fresnel integrals
Abstract
There are two standard ways of peeling an orange: either cut the skin along meridians, or cut it along a spiral. We consider here the second method, and study the shape of the spiral strip, when unfolded on a table. We derive a formula that describes the corresponding flattened-out spiral. Cutting the peel with progressively thinner strip widths, we obtain a sequence of increasingly long spirals. We show that, after rescaling, these spirals tends to a definite shape, known as the Euler spiral. The Euler spiral has applications in many fields of science. In optics, the illumination intensity at a point behind a slit is computed from the distance between two points on the Euler spiral. The Euler spiral also provides optimal curvature for train tracks between a straight run and an upcoming bend. It is striking that it can be also obtained with an orange and a kitchen knife.
Related
BibTeX
@article{bartholdi2026orange,
title = {{Orange peels and Fresnel integrals}},
author = {Laurent Bartholdi and André G. Henriques},
journal = {The Mathematical Intelligencer},
year = {2026},
month = nov,
doi = {10.1007/s00283-012-9304-1},
eprint = {1202.3033},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05849590v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Orange peels and Fresnel integrals
AU - Laurent Bartholdi
AU - André G. Henriques
PY - 2026
DA - 2026/11/03
JO - The Mathematical Intelligencer
DO - 10.1007/s00283-012-9304-1
UR - https://hal.science/hal-05849590v1
AB - There are two standard ways of peeling an orange: either cut the skin along meridians, or cut it along a spiral. We consider here the second method, and study the shape of the spiral strip, when unfolded on a table. We derive a formula that describes the corresponding flattened-out spiral. Cutting the peel with progressively thinner strip widths, we obtain a sequence of increasingly long spirals. We show that, after rescaling, these spirals tends to a definite shape, known as the Euler spiral. The Euler spiral has applications in many fields of science. In optics, the illumination intensity at a point behind a slit is computed from the distance between two points on the Euler spiral. The Euler spiral also provides optimal curvature for train tracks between a straight run and an upcoming bend. It is striking that it can be also obtained with an orange and a kitchen knife.
SN - 0343-6993
SN - 1866-7414
ER -