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Galaxy

A vast “island universe” of stars, gas, and dust. The universe may contain 100 billion or more galaxies. Galactic size and structure range from dwarfs and irregulars with no discernible structure and only a few million stars to giant spirals and ellipticals that span 100,000 light-years or more and contain hundreds of billions of stars. Galaxies clump together in web-like structures. Despite its great luminosity, most of a galaxy’s mass consists of dark matter, which produces no detectable energy.

Resources

Galaxies Fade May 21, 2010

Types of Galaxies May 21, 2010

Featured Images

Copeland's Septet, a collection of galaxies

Sparkling Septet January 18, 2021

artist's concept of ID2299, a galaxy that is losing much of its gas

Losing Gas January 12, 2021

NGC 247, a galaxy in Sculptor

Galactic Dark Zone December 7, 2020

Hercules galaxy cluster

Galaxies Everywhere July 25, 2020

Star Factory June 15, 2020

Artist's concept of a rotating disk galaxy in the early universe

Ancient Galaxy May 26, 2020

Hubble Space Telescope view of Messier 83, the Southern Pinwheel Galaxy

Mini Milky Way April 27, 2020

Multi-wavelength view of Messier 106

Arming a Galaxy April 5, 2020

Hubble Space Telescope view of galaxy NGC 4449

Windy Galaxy March 25, 2020

NGC 604 in the Triangulum Galaxy

Star Factory November 17, 2019

Hubble Space Telescope view of a pair of interacting galaxies

Beautiful Collision November 4, 2019

Busy Neighbor October 26, 2019

NGC 6052

Messy Merger August 20, 2019

Galaxy Centaurus A

Loud and Clear May 23, 2019

Galactic Nurseries March 11, 2019

Hubble Space Telescope view of D100, a galaxy that is losing gas as it plummets into the Coma Cluster

Running Out of Gas January 25, 2019

Hoag's Object, a ring galaxy

Galactic Ring November 7, 2018

HST view of NGC 1073

Step Up to the Bar November 6, 2018

Hubble Space Telescope view of Messier 101

Twisted Galaxy November 5, 2018

NGC 5907

Pancake Galaxy September 30, 2018

Atoms for Peace galaxy

'Peaceful' Galaxy September 28, 2018

Black holes around a ring galaxy

Ring Around the Galaxy September 8, 2018

multi-wavelength view of 3c 321

Death-Ray Galaxy June 10, 2018

the merging galaxy ngc 3256

Galactic Mash-Up June 2, 2018

Hubble Space Telescope view of spiral galaxy M64, the Black-Eye Galaxy

Galactic Black Eye May 13, 2018

Quasar 3c 298

'Pushy' Black Hole February 26, 2018

Hubble Space Telescope view of NGC 3344

Galactic Beauty February 15, 2018

A Hubble Space Telescope view of the galaxy NGC 1316

Odd Giant December 19, 2017

M33, the Triangulum Galaxy

Fuzzy Pinwheel November 18, 2017

Hubble view of Abel 370 galaxy cluster with intervening asteroids

Interlopers November 5, 2017

multi-wavelength views of the giant galaxy UGC 1382

Surprising Monster October 15, 2017

Multi-wavelength view of NGC 6946, the Fireworks Galaxy

Fireworks Factory August 23, 2017

The spiral galaxy Messier 77

Spiral Beauty July 12, 2017

Combined radio and visual view of the Perseus galaxy cluster

Hot Halo June 21, 2017

Hubble Space Telescope image of galaxy cluster Abell 370

Galactic Pile-Up May 15, 2017

Hubble view of hundreds of galaxies

Galaxy Glut May 5, 2017

Hubble Space Telescope view of galaxy M100

Grand Spiral April 19, 2017

Hubble Space Telescope view of galaxy NGC 6503

Island Universes April 17, 2017

HST view of Messier 82

Busy Galaxy March 26, 2017

Galaxy map shows

Sailing Through the Galaxies February 13, 2017

sequence of images depicting the merger of M31 and Milky Way galaxies

Crash Course January 11, 2017

Hubble Space Telescope view of the galaxy NGC 1300

Star Bar December 18, 2016

Swirling Galaxy December 3, 2016

Hubble Space Telescope view of M63

Galactic Sunflower August 26, 2016

Elliptical galaxy NGC 1600

Biggest of the Big June 28, 2016

Galactic Baubles April 14, 2016

Ground-based view of Coma cluster of galaxies

Sparkling Galaxies March 29, 2016

Artist's concept of the galaxy WISE 2246

Evaporating Galaxy March 22, 2016

Hubble view of M51, the Whirlpool galaxy, and its companion galaxy

Whirling Along March 3, 2016

Strong winds blowing from a black hole in a distant spiral galaxy

Windy Black Hole January 15, 2016

The odd galaxy NGC 660

Busy Galaxy December 18, 2015

Hubble view of galaxy Markarian 231

Double Double November 22, 2015

Hubble Space Telescope image of spiral galaxy Messier 66

Evidence of an Encounter April 12, 2015

Hubble Space Telescope view of Abell 2744, a massive galaxy cluster

On the Frontier March 9, 2015

Hubble image of the aftermath of a galactic collisio

Beautiful Disruption January 30, 2015

Gemini Observatory image of VV 166 galaxy group

Galaxies Galore January 11, 2015

Radio Programs

Super Clusters Super star clusters in a nearby galaxy December 8, 2020

Sculptor Galaxies A galaxy with a dark void December 7, 2020

Galaxy Pair Stirring up a pair of spiral galaxies November 27, 2020

Galactic Ripples Rippling through the Milky Way September 7, 2020

Hercules Galaxies A busy cluster of galaxies July 25, 2020

Galactic UFO A “UFO” from a giant black hole July 8, 2020

Southern Pinwheel Pinwheeling across the southern sky April 28, 2020

Galactic Fireworks Fireworks from a modest galaxy April 12, 2020

‘Windy’ Galaxies Busy galaxies that underperform March 25, 2020

Dwarf Galaxies Galaxies large and small March 24, 2020

Triangulum Galaxy A galaxy in a class of its own November 17, 2019

BL Lacertae A black hole that’s ablaze September 16, 2019

Merging Galaxies A messy galactic merger August 20, 2019

Galaxies Adding some lines to your address August 19, 2019

Hidden Galaxy A close galaxy hides from view August 1, 2019

Making Stars Stirring up stellar nurseries March 11, 2019

Mergers Giant galactic mergers February 14, 2019

Extreme Starbursts Taking starbirth to the extreme November 20, 2018

Ring Galaxies Beautiful galactic rings November 7, 2018

Barred Spirals Bellying up to the galactic bar November 6, 2018

Spiral Galaxies Jamming up some beautiful galaxies November 5, 2018

NGC 5907 Building up a flat galaxy September 30, 2018

Atoms for Peace A speech lives on in the stars September 28, 2018

Equal Galaxies? Balancing two big galaxies September 18, 2018

Void Galaxy A galaxy that’s on its own September 8, 2018

Death-Ray Galaxy A death ray from a monster black hole June 10, 2018

Black-Eye Galaxy Giving a galaxy a black eye May 13, 2018

Draco Dwarf A faint companion galaxy April 26, 2018

NGC 1316 Building an odd galaxy December 19, 2017

Early Light Looking for “fog” in the early universe December 15, 2017

Seeing Deep Looking deep into the early universe November 21, 2017

Monster Galaxy A monster within a monster October 15, 2017

Disappearing Star A potential firecracker fizzles out August 23, 2017

Hyperactive Galaxy A galaxy with lots of fireworks August 22, 2017

Leo’s Triplets A galactic trio in the lion May 11, 2017

Galaxies “Island universes” across the cosmos April 17, 2017

Growth Spurt A growth spurt in a distant galaxy March 27, 2017

M82 A gas crisis for a vigorous galaxy March 26, 2017

Active Galaxies “Activating” the heart of a galaxy March 14, 2017

Barred Spirals Stepping up to the galactic bar December 18, 2016

Dark Matters Lighting up the darkness December 16, 2016

Brightest Galaxy The distant glow of a brilliant galaxy October 1, 2016

Sunflower Galaxy Sculpting a galactic sunflower August 26, 2016

Scutum Arm Wrapping an arm around the galaxy July 25, 2016

Moon and Spica An act of galactic cannibalism July 11, 2016

Grand M81 A “grand design” for a galaxy May 24, 2016

Super Spirals Making beautiful giant galaxies April 2, 2016

Hydra I A faint companion to the Milky Way April 1, 2016

Lacy Galaxies Finding big but hazy galaxies March 31, 2016

Evaporating Galaxy A galaxy that’s ripping itself apart March 23, 2016

Black Hole Snowplow Snowplowing lanes around a black hole March 4, 2016

Galactoseismology Ripples from a “galaxy quake” March 2, 2016