Galaxy

Cosma / Communication / Knowledge / Realm / Physical / Universe / Galaxy
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galaxy : any of the large groups of stars and associated matter that are found throughout the universe — Merriam-Webster See also OneLook

Thesaurus

Roget’s II (Thesaurus.com), Merriam-Webster Thesaurus, Visuwords

Encyclopedia

Galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. Galaxies contain varying amounts of star systems, star clusters and types of interstellar clouds. In between these objects is a sparse interstellar medium of gas, dust, and cosmic rays. Dark matter appears to account for around 90% of the mass of most galaxies. — Wikipedia

Galaxy (Encyclopædia Britannica)

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Inspiration

Astrum (YouTube Channel)
Astrum (Facebook Page)

Hubble Skymap puts the night sky at your fingertips any time of day. Roam the Milky Way to find a selection of stars and nebulae as seen by Hubble. To explore the skymap, scroll, double click, or pinch/swipe to zoom in and out. Roll over an icon to see the object, click to zero in, and click again for a detailed view and a description. Drag the map to navigate. — Hubble Skymap (NASA Science)

Hubble Skymap (NASA Science)

Hubble’s Galaxies is a collection of galaxy images from the Hubble Space Telescope — Hubble’s Galaxies

Hubble’s Galaxies (NASA Science)

Big Idea 9: There are Hundreds of Billions of Galaxies in the Universe (Big Ideas in Astronomy, International Astronomical Union)

Talks about Galaxies (TED: Ideas Worth Spreading)
Articles about Galaxies (Big Think)

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Innovation

Science

Galactic Astronomy is the study of the Milky Way galaxy and all its contents.The Milky Way galaxy, where the Solar System is located, is in many ways the best-studied galaxy, although important parts of it are obscured from view in visible wavelengths by regions of cosmic dust. The development of radio astronomy, infrared astronomy and submillimetre astronomy in the 20th century allowed the gas and dust of the Milky Way to be mapped for the first time. — Wikipedia

Extragalactic Astronomy is the branch of astronomy concerned with objects outside the Milky Way galaxy. In other words, it is the study of all astronomical objects which are not covered by galactic astronomy. The closest objects in extragalactic astronomy include the galaxies of the Local Group, which are close enough to allow very detailed analyses of their contents (e.g. supernova remnants, stellar associations). — Wikipedia

Astronomic (YouTube Channel)
Astronomic (Facebook)

Galaxies (NASA Science)
What are Galaxies? (NASA Science)
Galaxies (Imagine the Universe, NASA Goddard Space Flight Center)

Galaxy Videos (ViewSpace, Space Telescope Science Institute)
Galaxy Evolution Videos (ViewSpace, Space Telescope Science Institute)
Galaxy Structure Videos (ViewSpace, Space Telescope Science Institute)

Galaxies (Lunar & Planetary Institute)
Galaxies and Cosmology (Max Planck Institute for Astronomy)

Galaxies (Eric Weisstein’s World of Astronomy, Wolfram Research)
Galactic Astronomy (Eric Weisstein’s World of Astronomy, Wolfram Research)

Galaxies (Wolfram Alpha)

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Preservation

History

Historical Overview of the Discovery of Galaxies (Earth Guide)
Historical Overview of the Discovery of Galaxies (Introduction to Astronomy, Wolfgang H. Berger, UC San Diego)
Timeline of Knowledge about Galaxies, Clusters of Galaxies … (Wikipedia)

Library

DDC: 523.112 Galaxies (Library Thing)
Subject: Galaxies (Library Thing)

Subject: Galaxies (Open Library)

LCC: QB 856 Galaxies (Library of Congress)

Subject: Galaxies (WorldCat)

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Participation

Education

Science Education Videos (NASA Goddard Space Flight Center, YouTube Playlist)
NASA Goddard Space Flight Center (Official Website)

What is a Galaxy? (Space Place, NASA)
Galaxies (Imagine the Universe, NASA Goddard Space Flight Center)

Galaxies (Science Trek)
Galaxies (Cosmos4Kids)
Galaxies (Space Scoop)

Galaxies (Astronomy Center, ComPADRE)

Galaxies, Part 1 (Crash Course Astronomy, YouTube Video)
Galaxies, Part 2 (Crash Course Astronomy, YouTube Video)

MERLOT: Multimedia Educational Resource for Learning and Online Teaching
OER Commons: Open Educational Resources

Community

Organization

International Astronomical Union Division J – Galaxies and Cosmology

News

Galaxies (Nova Research Highlights, American Astronomical Society)

Galaxies (EurekaAlert, AAAS)
Galaxies (JSTOR)

Galaxies (Sky & Telescope, AAS)
Galaxies (Astronomy Magazine)

Galaxies (Science Daily)
Galaxies (Phys.org)

Recent News from Phys.org …

Exploding primordial black holes might have...
on April 5, 2026 at 12:00 pm
The early universe is absolutely so far outside our understanding of how the world works it's hard to describe in words. Back then, the cosmos wasn't filled with stars and galaxies but with a boiling soup of quarks and gluons, with a few microscopic black holes thrown in, occasionally detonating like depth charges. That's the early universe theorized by a new paper, available in pre-print from arXiv, from researchers at Vrije Universiteit Brussel and MIT anyway.
The Habitable Worlds Observatory will need...
on April 3, 2026 at 4:20 pm
We're getting closer and closer to finding a real Earth-like exoplanet. But finding one is only half the battle. To truly know if we're looking at an Earth analog somewhere else in the galaxy, we have to directly image it too. That's a job for the Habitable Worlds Observatory (HWO), a planned space-based telescope whose primary job is to do precisely that. But even capturing a picture and a planet and getting spectral readings of its atmospheric chemistry still isn't enough, according to a new […]
The most pristine star yet found in the known...
on April 3, 2026 at 3:40 pm
An unusual team of astronomers used Sloan Digital Sky Survey-V (SDSS-V) data and observations on the Magellan telescopes at Carnegie Science's Las Campanas Observatory in Chile to discover the most pristine star in the known universe, called SDSS J0715-7334. Their work is published in Nature Astronomy.
Webb eyes a pair of planet-forming disks
on April 3, 2026 at 3:10 pm
This month's NASA/ESA/CSA James Webb Space Telescope Picture of the Month offers us a two-for-one on brand new stars—with some potential planets thrown in as well. This visual highlights Webb's views of the protoplanetary disks Tau 042021 (left) and Oph 163131 (right), otherwise known by the catalog numbers 2MASS J04202144+2813491 and 2MASS J16313124-2426281, respectively. Tau 042021 is situated around 450 light-years from Earth in the constellation Taurus, while Oph 163131 lies about 480 […]
Astronomers find a third galaxy missing its dark...
on April 2, 2026 at 7:30 pm
Astronomers have long argued that dark matter is the invisible scaffolding that holds galaxies together. Without its immense gravitational pull, the rotational spins of galaxies would force them to simply fly apart. But now, scientists have found a string of galaxies that seem to be missing their dark matter entirely. The latest in this string, known as NGC 1052-DF9, is described in a new paper available on the arXiv preprint server, by Michael Keim, Pieter van Dokkum and their team from Yale. […]