Cosma / Communication / Knowledge / Realm / Physical / Universe / Galaxy / Andromeda
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Introduction1
NASA Goddard (YouTube Channel)
NASA Goddard Space Flight Center (Official Website)
Encyclopedia
Andromeda Galaxy, also known as Messier 31, M31, or NGC 224, is a spiral galaxy approximately 780 kiloparsecs (2.5 million light-years) from Earth, and the nearest major galaxy to the Milky Way. Its name stems from the area of the sky in which it appears, the constellation of Andromeda.
The 2006 observations by the Spitzer Space Telescope revealed that the Andromeda Galaxy contains approximately one trillion stars, more than twice the number of the Milky Way’s estimated 200 to 400 billion stars. The Andromeda Galaxy, spanning approximately 220,000 light-years, is the largest galaxy in our Local Group, which is also home to the Triangulum Galaxy and other minor galaxies. The Andromeda Galaxy’s mass is estimated to be around 1.76 times that of the Milky Way Galaxy (~0.8-1.5×1012 solar masses vs the Milky Way’s 8.5×1011 solar masses). — Wikipedia
Andromeda (Encyclopædia Britannica)
Andromeda (COSMOS: The SAO Encyclopedia of Astronomy)
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Inspiration
This video begins with a ground-based view of the night sky, before zooming in on a Hubble image of the Andromeda galaxy — otherwise known as M31. The Hubble image of the galaxy is the biggest Hubble image ever released and shows over 100 million stars and thousands of star clusters embedded in a section of the galaxy’s pancake-shaped disc stretching across over 40 000 light-years.ESA/Hubble
Zooming in on the Andromeda Galaxy (ESA/Hubble)
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Innovation
Science
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
The Milky Way and Andromeda galaxies are expected to collide in ~4.5 billion years, merging to form a giant elliptical galaxy or a large disc galaxy. With an apparent magnitude of 3.4, the Andromeda Galaxy is among the brightest of the Messier objects — making it visible to the naked eye on moonless nights, even when viewed from areas with moderate light pollution. — Wikipedia
ScienceAtNASA (YouTube Channel)
NASA Science (Official Website)
This animation depicts the collision between our Milky Way galaxy and the Andromeda galaxy. Hubble Space Telescope observations indicate that the two galaxies, pulled together by their mutual gravity, will crash together about 4 billion years from now. Around 6 billion years from now, the two galaxies will merge to form a single galaxy. The video also shows the Triangulum galaxy, which will join in the collision and perhaps later merge with the Andromeda/Milky Way pair.
NASA Video (YouTube Channel)
NASA (Official Website)
Colliding Galaxies Videos (ViewSpace, Space Telescope Science Institute)
Interacting Galaxies: Future of the Milky Way Interactives (ViewSpace, Space Telescope Science Institute)
The Once and Future Stars of Andromeda (NASA Science)
Messier 31: The Andromeda Galaxy (Hubble’s Messier Catalog, NASA)
Andromeda Galaxy Videos (ViewSpace, Space Telescope Science Institute)
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Preservation
History
Dec. 30, 1924: Hubble Reveals We Are Not Alone (Randy Alfred, Wired Magazine)
Library
Subject: Andromeda Galaxy (Library Thing)
Subject: Andromeda Galaxy (Open Library)
Subject: Andromeda Galaxy (WorldCat)
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Participation
Education
MERLOT: Multimedia Educational Resource for Learning and Online Teaching
OER Commons: Open Educational Resources
Community
News
Andreomeda Galaxy (JSTOR)
Andreomeda (EurekaAlert, AAAS)” target=”_blank” rel=”noopener”>Andromeda Galaxy (EurekaAlert, AAAS)
Andromeda Galaxy (Astronomy Magazine)
Andromeda (Phys.org)
Recent News from Phys.org …
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- New gallery of galaxies from NASA's Chandra X-ray...
on August 25, 2026 at 4:56 pmGalaxies are like cosmic gems, each with characteristics including size and shape that make them distinct. A new gallery released today from NASA's Chandra X-ray Observatory and other telescopes displays a collection of galactic images that showcase this variety.
- How to keep the Earth habitable when the sun dies
on August 3, 2026 at 8:40 pmIn a billion years, the sun will start to run out of fuel and expand to become a red giant. Earth's oceans and atmosphere will be burned away, and Earth will likely be engulfed by the sun altogether. The sun will then shrink to a dim white dwarf, and all light and warmth in the solar system will diminish. In a hundred trillion years, the galaxy's ability to produce stars will be exhausted, and everything will turn dark. However, there's a way for life to escape this fate—and what's more, we […]
- Hubble shows star formation in Andromeda galaxy...
on July 27, 2026 at 9:20 pmA new study using data from NASA's Hubble Space Telescope finds that star formation in the nearby Andromeda galaxy has undergone a 500-million-year decline, with an even steeper drop in the last 40 million years. Andromeda, a spiral galaxy comparable in size to our Milky Way, is close enough to be seen with the unaided eye from areas with dark skies. Located about 2.5 million light-years from Earth—practically our cosmic backyard—Andromeda offers an opportunity for astronomers to examine […]
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Related
Here are links to pages about closely related subjects.
“Fundamentals”
Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle
“Space”
Universe (Astronomical Instrument)
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon
Our Neighborhood
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid
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Notes
1. The resources on this page are are organized by a classification scheme developed exclusively for Cosma.