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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Adventures

Explore related posts on Cosma …

Milky Way Lost & Found - Have you seen the Milky Way? You may think that you have, but are you sure? Unless you live in an extremely remote area, or you’ve visited one, then you probably haven’t seen our own galaxy, the Milky Way, very well, or at all. Worse yet, you may not even realize that it’s missing. The … Continue reading Milky Way Lost & Found

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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 …

Newfound 'baby' planet smashes record for...
on September 16, 2026 at 8:00 pm
Astronomers have confirmed a world less than a million years old as the youngest known planet, using data from archives. Called Elias 2-24 b, the baby planet is still whirling in its natal disk of dust and gas.
Nearly 50 'ghost galaxies' emerge around three...
on September 16, 2026 at 12:40 pm
Dwarf galaxies—with a mass equal to about a billion suns, but often considerably less—are the most abundant in the universe. However, because of their low luminosity, they are very difficult to detect. They have mostly been discovered in the vicinity of the Milky Way, in what is called the Local Group, but also, and in large quantities, at greater distances, where current instrumentation cannot distinguish individual stars.
Webb measures extreme gas outflows from distant...
on September 16, 2026 at 12:10 pm
Astronomers using the James Webb Space Telescope have measured the most powerful gas outflow ever recorded from a "dead" galaxy outside our cosmic neighborhood and found that even outflows this extreme may not be enough to permanently shut down star formation.
Magnets could help quantum computers talk to each...
on September 15, 2026 at 8:00 pm
Xufeng Zhang is using magnets to make computers more power efficient at the quantum level. The Northeastern professor of electrical and computer engineering recently published two papers highlighting small-scale magnetic systems he and his team developed that could help make computers much more power efficient in the future.
A famous galaxy's black hole has been hiding its...
on September 15, 2026 at 11:20 am
Astronomers have found that a nearby galaxy's black hole is blasting out a far more powerful and hidden gas outflow than previously realized. Studying NGC 1068, a well-known galaxy with an actively feeding black hole at its center, researchers combined new infrared observations with existing data to map how the black hole's energy is reshaping the surrounding gas. The results are reported in a paper published Aug. 6 in Astronomy & Astrophysics.