This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| Zone of Avoidance | |
|---|---|
| Name | Zone of Avoidance |
| Caption | Obscuration of extragalactic sky by the Milky Way |
| Type | Astronomical region |
| Coordinates | Galactic plane |
| Discovered | 1878 (roughly) |
| Notable objects | Great Attractor, Perseus–Pisces Supercluster |
Zone of Avoidance The Zone of Avoidance is the region of the sky heavily obscured by the Milky Way's disk where foreground extinction and stellar crowding hide background galaxys, creating a gap in extragalactic catalogs and maps. Its existence has influenced the development of astronomy techniques, motivated multiwavelength surveys, and complicated assessments of the large-scale structure of the Universe and the distribution of mass linked to features like the Great Attractor and the Local Group's motion.
The Zone of Avoidance marks low galactic latitudes near the plane of the Milky Way where dust lanes in the Orion Arm and stellar density in regions toward Sagittarius, Scorpius, and Cygnus obscure background Andromeda, M87, Virgo Cluster members and more distant systems. Historically recognized in star catalogs and sky surveys conducted by groups such as the Royal Astronomical Society observers and catalogers at the Harvard College Observatory, the Zone produces anisotropies in redshift surveys like those from the Two Micron All Sky Survey and the Sloan Digital Sky Survey that require correction to compare with maps from missions including Planck and COBE.
Early recognition came from nineteenth-century catalogers such as John Herschel and surveyors in the era of the Carte du Ciel and Henry Draper Catalogue, who noted an apparent paucity of nebulae along the galactic equator compared with higher latitudes. In the twentieth century, systematic work by teams at institutes like the Mount Wilson Observatory and the Palomar Observatory refined counts of extragalactic sources, while radio astronomers at observatories such as the Jodrell Bank Observatory and the National Radio Astronomy Observatory used 21-cm HI surveys to penetrate obscuration and reveal hidden spirals implicated in flows toward the Shapley Supercluster and the Great Attractor. Observational campaigns by researchers affiliated with the European Southern Observatory and the Max Planck Institute for Astrophysics extended coverage into the southern sky, complementing northern efforts by groups tied to the California Institute of Technology and the Harvard–Smithsonian Center for Astrophysics.
The Zone arises primarily from extinction by interstellar dust in the Sagittarius Arm and molecular clouds such as the Taurus Molecular Cloud and Ophiuchus cloud complex, combined with extreme stellar crowding toward the Galactic Center and regions near Baade's Window. Interstellar dust grains associated with elements traced by teams working on IRAS and Spitzer Space Telescope observations absorb and scatter optical light, while mid-infrared and radio emissions mapped by WISE and Arecibo Observatory studies reveal hidden mass. The obscuration affects interpretations of peculiar velocities measured in studies led by researchers at institutions like the University of Cambridge and Princeton University, complicating attribution of flows toward attractors such as the Norma Cluster and the Perseus–Pisces Supercluster.
Multiwavelength approaches developed by consortia involving the European Space Agency, NASA, and national facilities overcame optical limitations: near-infrared surveys like Two Micron All Sky Survey and DENIS reduce dust extinction; 21-cm HI surveys by teams at the Arecibo Observatory and the Parkes Observatory detect neutral hydrogen in spiral galaxies; far-infrared missions including IRAS and Herschel Space Observatory trace thermal dust emission; X-ray observatories such as ROSAT and Chandra X-ray Observatory reveal galaxy clusters via hot intracluster gas; and radio continuum arrays like the Very Large Array and the Atacama Large Millimeter/submillimeter Array map active galactic nuclei and star-forming regions. Data fusion efforts involving the Centre de Données astronomiques de Strasbourg and the International Astronomical Union working groups standardize catalogs to correct for selection effects.
Major efforts addressing the Zone include the Two Micron All Sky Survey, the HI Parkes All Sky Survey led by groups at the Australian National University, the 2MASS Redshift Survey by researchers at the University of Massachusetts Amherst and IPAC, and targeted optical follow-ups by teams from the European Southern Observatory. These campaigns uncovered structures such as the Great Attractor region near the Norma Cluster, the extension of the Perseus–Pisces Supercluster across the galactic plane, and the concentration associated with the Shapley Supercluster. Surveys coordinated with instruments at the Arecibo Observatory, the Parkes Observatory, and facilities operated by the National Astronomical Observatory of Japan produced redshift catalogs that filled previously blind patches, aiding work by investigators at the Max Planck Institute for Extraterrestrial Physics and the Kavli Institute for Cosmology.
The Zone's obscuration biases measurements of galaxy counts, redshift-space distortions, and the inferred dipole of the Cosmic Microwave Background as studied by teams behind Planck (spacecraft) and WMAP. Correcting for the Zone using data from 2MASS, HI surveys, and X-ray cluster catalogs influences estimates of cosmic parameters derived by collaborations at the European Southern Observatory, Princeton University, and the Johns Hopkins University, and affects reconstructions of peculiar velocity fields used to probe dark matter distributions linked to models from the Lambda-CDM model community at institutes such as Institute for Advanced Study and Lawrence Berkeley National Laboratory. Filling the Zone reduces systematic uncertainties in mapping superclusters like Shapley Supercluster and verifying predictions from simulations run by groups at the Max Planck Institute for Astrophysics and CERN.
Category:Astronomical regions