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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.


Galaxies Fade May 21, 2010

Types of Galaxies May 21, 2010

Radio Programs

NGC 7469 Starbirth in a busy galaxy September 16, 2023

Milky Way Satellites A flock of galactic sheep August 17, 2023

Messier 110 A faint member of a galactic empire August 10, 2023

Moaning Black Hole The sounds of a giant black hole August 6, 2023

Sombrero Galaxy Knowledge from a galactic sombrero May 31, 2023

Big Jellyfish Sculpting a galactic jellyfish May 19, 2023

Data Factory Plunging into mounds of data April 27, 2023

Making a Giant Stirring up a beast of a galaxy April 20, 2023

The Sunflower A good night for watching galaxies March 22, 2023

Galactic Fossils Colorful galactic “fossils” March 13, 2023

Early Galaxies Deep looks at the first galaxies March 6, 2023

Hoag’s Object An appetizing galaxy July 24, 2022

Galaxies Aplenty Blocking out millions of galaxies May 26, 2022

Looking Up The best place for galaxy hunting April 3, 2022

Megamasers Powering up some distant galaxies February 7, 2022

NGC 2217 Sculpting a unique galaxy February 6, 2022

M33 Looking three million light-years into space January 30, 2022

Busy Galaxy New stars by the thousands September 21, 2021

Green Peas Dishing up some busy little galaxies September 10, 2021

IC 1101 The king of the mega-merger April 27, 2021

Pipsqueak Galaxies Tiny companions to the Milky Way April 26, 2021

GN-z11 A trip to the early universe April 12, 2021

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

Featured Images

false-color infrared image of galaxy M51 by james webb space telescope

Busy Whirlpool September 2, 2023

the galaxies m31 and one of its satellites, m110

Double Beauties August 10, 2023

composite image of ngc 1275, a giant galaxy in the middle of the perseus cluster

Loud Black Hole August 6, 2023

Galactic Merger July 26, 2023

sombrero galaxy

Brimmed Galaxy May 31, 2023

Ghostly clouds of hot gas glow bright blue against a background of many distant galaxies

Ghostly Gas March 31, 2023

field of galaxies from webb telescope

Pandora's Bounty February 16, 2023

merging spiral galaxies

Getting Together August 10, 2022

Hoag's Object, an unusual ring galaxy

Hitting the Bullseye July 24, 2022

First full-color James Webb Space Telescope image

First View July 11, 2022

tiny dwarf galaxy

Hiding in Plain Sight July 1, 2022

hubble view of distant galaxies

Galaxies Aplenty May 26, 2022

hubble view of arp 143, a pair of colliding galaxies

Cosmic Collision February 25, 2022

ngc 2217, a barred spiral galaxy

Galactic Bar February 6, 2022

Recent view of Centaurus A, a giant galaxy

Galactic Contrast September 1, 2021

spiral galaxy ARP-MADORE0002-503

Back to Work July 22, 2021

ngc 4303

New Stars Galore July 17, 2021

New view of Messier 106

Wonky Galaxy March 19, 2021

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