Local Void

The Local Void is a large, low-density region of space adjoining the Local Group. It is part of the nearby cosmic web and contains far fewer galaxies than surrounding regions.

Cosmic void: A vast region of the universe with a lower-than-average density of galaxies and matter. The Local Void is a nearby example of this large-scale cosmic structure.
Local Group: The gravitationally bound association of the Milky Way, Andromeda, and dozens of smaller galaxies. The Local Group lies along the Local Void's boundary.
Cosmic microwave background: Relic radiation released when the early universe became transparent, now observed across the sky. Its tiny temperature variations trace the early fluctuations from which voids grew.
Hubble tension: The disagreement between measurements of the present expansion rate using different methods. Local underdensities have been proposed as a partial explanation for differences in nearby expansion measurements.
Peculiar velocity: An object's motion relative to the uniform expansion of the universe. Galaxy motions around the Local Void help reveal its gravitational influence.
Milky Way: The barred spiral galaxy that contains the Solar System. Its position near the void's edge anchors one side of the local environment.
Cosmological principle: The assumption that the universe is statistically homogeneous and isotropic on sufficiently large scales. The Local Void illustrates why large local underdensities can coexist with large-scale uniformity.
Cosmicflows: A research program mapping galaxy distances and motions to reconstruct nearby cosmic structure. Its velocity maps help constrain the Local Void's extent and dynamical influence.
Hubble flow: The general recession of distant galaxies caused by the expansion of the universe. It provides the expanding background against which local motions around the void are measured.
Andromeda Galaxy: The large spiral galaxy nearest the Milky Way and the most massive member of the Local Group. Its location helps map the Local Group's relationship to the void.

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