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Galaxies

Universe Galaxies-1 Milky Way

Artist's Conception - The Milky Way
Where are we?
We live in a somewhat remote arm of the Milky Way. This video shows you the way from our home to a vantage point outside the Local Group.
Animation (Quicktime, 3MB)

Universe Galaxies-3 Deep Field
Hubble Ultra Deep Field galaxies:
Credit: NASA, ESA, S. Beckwith (STScI) and the HUDF Team

Our galaxy, the Milky Way, is typical: it has hundreds of billions of stars, enough gas and dust to make billions more stars, and at least ten times as much dark matter as all the stars and gas put together. And it’s all held together by gravity.

Like more than two-thirds of the known galaxies, the Milky Way has a spiral shape. At the center of the spiral, a lot of energy and, occasionally, vivid flares. are being generated. Based on the immense gravity that would be required explain the movement of stars and the energy expelled, the astronomers conclude that the center of the Milky Way is a supermassive black hole.

Other galaxies have elliptical shapes, and a few have unusual shapes like toothpicks or rings. The Hubble Ultra Deep Field (HUDF) shows this diversity. Hubble observed a tiny patch of sky (one-tenth the diameter of the moon) for one million seconds (11.6 days) and found approximately 10,000 galaxies, of all sizes, shapes, and colors. From the ground, we see very little in this spot, which is in the constellation Fornax.

Formation

After the Big Bang, the Universe was composed of radiation and subatomic particles. What happened next is up for debate - did small particles slowly team up and gradually form stars, star clusters, and eventually galaxies? Or did the Universe first organize as immense clumps of matter that later subdivided into galaxies?

Collisions

The shapes of galaxies are influenced by their neighbors, and, often, galaxies collide. The Milky Way is itself on a collision course with our nearest neighbor, the Andromeda galaxy. Even though it is the same age as the Milky Way, Hubble observations reveal that the stars in Andromeda's halo are much younger than those in the Milky Way. From this and other evidence, astronomers infer that Andromeda has already smashed into at least one and maybe several other galaxies.

Recent Discoveries

July 9, 2015 A Galaxy in Bloom (ESO 381-12)
July 6, 2015 Galaxy with a View (LEDA 89996)
June 3, 2015 Charting the Milky Way from the Inside out
May 28, 2015 Galaxies with Relativistic Jets
May 21, 2015 WISE Spacecraft Discovers Most Luminous Galaxy in Universe
May 7, 2015 Hubble Finds Giant Halo Around the Andromeda Galaxy
May 5, 2015 Astronomers Set a New Galaxy Distance Record
April 27, 2015 Galactic Refurbishment (emission line galaxy)
April 20, 2015 Extragalactic Peculiarity
April 9, 2015 Our Sun Came Late to the Milky Way's Star-Birth Party
March 16, 2015 An Intriguing Young-looking Dwarf Galaxy (PGC 51017)
January 29, 2015 Hubble Spies a Loopy Galaxy (NGC 7714)
January 26, 2015 Polar Ring of Arp 230
January 19, 2015 Dust Filaments of NGC 4217
January 5, 2015 Hubble's Panoramic View of the Andromeda Galaxy
December 18, 2014 Chandra Weighs Most Massive Galaxy Cluster in Distant Universe (XDCP J0044.0-2033)
November 13, 2014 Party's Over for These Youthful Compact Galaxies
November 6, 2014 Rocket Experiment Finds the Universe is Brighter Than We Thought
October 30, 2014 Hubble Sees 'Ghost Light' from Dead Galaxies
October 27, 2014 Chandra Identifies Impact of Cosmic Chaos on Star Birth (Perseus and Virgo Clusters)
October 16, 2014 Hubble Finds Extremely Distant Galaxy through Cosmic Magnifying Glass
September 15, 2014 An Interacting Colossus (NGC 6872 and IC 4970)
September 8, 2014 A Spattering of Blue (irregular galaxy IC 559)