Quipu is the largest reliably identified cosmic superstructure to date, a branching filament spanning about 1.4 billion light-years and containing roughly 200 quadrillion solar masses in a network of galaxy clusters, galaxies, gas, and dark matter.

This discovery matters for precision cosmology because nearby mass concentrations influence peculiar velocities and gravitational lensing, potentially affecting measurements like the Hubble constant and the integrated Sachs-Wolfe effect, though Planck-aligned expectations need stronger statistical confirmation.

Quipu is presented as both a record and a working map of the local cosmic web, with edges and membership adjustable as new X-ray and galaxy survey data refine its boundaries.

The structure was identified using the CLASSIX X-ray cluster catalog, formed from NORAS and REFLEX surveys, and is defined by a three-dimensional shell around Earth with percolation-based linking that yields 68 member clusters, 63 of which lie within the target redshift range.

Quipu does not contradict the standard Lambda-CDM cosmology; its length is compatible with a statistically homogeneous universe, with simulations like Millennium producing comparable extreme structures within expected distributions.

It is not a single gravitationally bound object; rather, Quipu is a coherent feature of the present matter distribution in the local cosmic web, with some portions bound locally and others expanding with cosmic expansion.

Quipu’s length is 428 megaparsecs, marking the maximum straight-line separation between its member clusters, and its mass estimate comes from converting the cluster overdensity to an underlying matter overdensity, acknowledging bias factor uncertainties.

The label ‘largest reliably identified’ reflects rigorous mapping and cross-checks, confirmed by an almost all-sky X-ray cluster sample with a documented selection function and corroborated by independent 2MASS galaxy maps, setting it apart from larger but less robustly mapped structures.