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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

April 24, 2014 Galaxies Spiraling Around Leo (NGC 3455)
April 17, 2014 A Cross-Section of the Universe
April 3, 2014 Monster 'El Gordo' Galaxy Cluster is Bigger Than Thought
March 20, 2014 GLIMPSE the Galaxy All the Way Around
March 4, 2014 Life is Too Fast, Too Furious for This Runaway Galaxy (ESO 137-001)
February 18, 2014 Hubble Watches Stars' Clockwork Motion in Nearby Galaxy
(Large Magellanic Cloud)
February 7, 2014 One of the Youngest Galaxies in the Universe (Abell2744_Y1)
February 6, 2014 A New Look at an Old Friend (Centaurus A)
January 29, 2014 Mystery of Ultra-Compact, Burned-Out Galaxies
January 7, 2014 Deep Sea of Small and Faint Early Galaxies
 January 6, 2014 First Gamma-ray Study of a Gravitational Lens
December 18, 2013 Galactic Metropolis
November 21, 2013 Infant Galaxies Merging Near 'Cosmic Dawn'
November 14, 2013 Hubble Reveals First Scrapbook Pictures of Milky Way's Formative Years
October 31, 2013 Galaxy Growth Examined Like Rings of a Tree
October 30, 2013 Study Points to Early Cosmic 'Seeding' (Perseus Galaxy Cluster)
October 23, 2013 Galaxy Found Has Farthest Confirmed Distance (z8_GND_5296)
September 24, 2013 Evidence of Densest Galaxy in Nearby Universe (M60-UCD1)
September 19, 2013 Clues to the Growth of the Colossus (in Coma Cluster)
September 12, 2013 Largest Known Population of Star Clusters
August 22, 2013 Barred Sculptor Galaxy
August 15, 2013 True Shapes of Galaxies 11 Billion Years Back in Time
August 14, 2013 Dwarf Galaxy Caught Ramming into a Large Spiral (NGC 1232)
August 8, 2013 Hubble Finds Source of Magellanic Stream
August 1, 2013 Monster in the MIddle: Brightest Cluster Galaxy