The Milky Way Galaxy

ESO Alma Telescopes and the Milky Way
Credit: ESO/José Francisco Salgado
Four of the European Southern Observatory's Atacama Large Millimeter/submillimeter Array (ALMA) antennas gaze up at the night sky. Milky Way is visible at left.

The current night sky is dominated by the white glow of myriad middle-aged stars along the lane of the Milky Way. Interstellar "pollution" from thick dust lanes can be seen threading through the long band of stars. They are interspersed with a few pinkish emission nebulae from ongoing star formation. Thousands of stars appear as pinpoints of light throughout the sky.
Credit: NASA, ESA, and Z. Levay (STScI/AURA)

The Milky Way and green airglow are captured over the Isle of Wight in this image taken by Chad Powell on Oct. 4, 2013, using a Canon 6D camera (25 seconds, f/2.8, 20mm, and ISO 4000). 
Credit: Chad Powell | Isle of Wight Milky Way Photography |

Evolution of Milky Way Galaxy Revealed by Hubble Space Telescope
by Mike Wall, Senior Writer   |   November 15, 2013 07:30am ET

Astronomers have pieced together a detailed picture of how our Milky Way galaxy came together, using Hubble Space Telescope photos of 400 similar galaxies at various stages of evolution.

"For the first time we have direct images of what the Milky Way looked like in the past," study co-leader Pieter van Dokkum, of Yale University in New Haven, Conn., said in a statement.

"Of course, we can't see the Milky Way itself in the past. We selected galaxies billions of light-years away that will evolve into galaxies like the Milky Way," van Dokkum added. "By tracing the Milky Way's siblings, we find that our galaxy built up 90 percent of its stars between 11 billion and 7 billion years ago, which is something that has not been measured directly before." 

Hubble's images suggest that the Milky Way started out as a faint blue object with lots of gas, clouds of which eventually collapsed to form stars. At the time of peak star formation throughout the universe — about 4 billion years after the Big Bang— galaxies like the Milky Way were pumping out about 15 new stars per year, researchers said. (For comparison, the Milky Way produces just one star a year these days.)

The data further reveal that the Milky Way's flat disk and central bulge formed at about the same time, scientists said.

"You can see that these galaxies are fluffy and spread out," study co-leader Shannon Patel, of Leiden University in the Netherlands, said in a statement. "There is no evidence of a bulge without a disk, around which the disk formed later."

What a difference 11 billion years makes, as can be seen in these two comparative views of our Milky Way galaxy. The top view shows how our galaxy looks today; the bottom view, how it appeared in the remote past. This photo illustration is based on a Hubble Space Telescope survey of evolving Milky Way-type galaxies.
Credit: NASA, ESA, and Z. Levay (STScI)

That's in contrast to huge elliptical galaxies, in which the bulge appears first, team members added. Further, galaxy mergers are thought to be important in the evolution of ellipticals, while spirals like the Milky Way likely grow primarily by star formation.

"These observations show that there are at least two galaxy-formation tracks," van Dokkum said. 

"Massive ellipticals form a very dense core early in the universe, including a black hole, presumably, and the rest of the galaxy slowly accretes around it, fueled by mergers with other galaxies. But from our survey we find that galaxies like our Milky Way show a different, more uniform path of growing into the majestic spirals we see today."

The researchers incorporated data from three different Hubble Space Telescope observing programs — the 3D-HST survey, the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey and the Great Observatories Origins Deep Survey. Team members measured each of the 400 galaxies' distance and size, which they calculated using information about its brightness and color.

Part of the team's findings were published July 10 in The Astrophysical Journal Letters, while a second paper appears in the Nov. 11 online edition of The Astrophysical Journal.

The Milky Way over the 1.54-Meter Danish Telescope at La Silla
Credit: ESO/Z. Bardon/ProjectSoft
The Milky Way shines over the 1.54-meter Danish telescope at La Silla, Chile.

Echinopsis Atacamensis and the Milky Way
Credit: ESO/S. Guisard
The Milky Way is seen in all its glory, as well as, in the lower right, the Large Magellanic Cloud.

Before the Meteor Rush
Credit: Tamas Ladanyi (
This bright Perseid meteor streaking through skies near Lake Balaton, Hungary on August 8, 2010, served as advance guard for the meteor shower that was scheduled to peak a few days later. In the foreground stands the region's Church of St. Andrew ruin, with bright Jupiter dominating the sky to its right. Two galaxies lie in the background: our own Milky Way, and the faint smudge of the more distant Andromeda Galaxy just above the ruin's leftmost wall.

3 Telescopes Combine for Stunning Milky Way Photo
Credit: NASA, ESA, SSC, CXC, and STScI
In this spectacular image, observations using infrared light and X-ray light see through the obscuring dust and reveal the intense activity near the galactic core of the Milky Way. The image combines pictures from the Hubble Space Telescope, Spitzer Space Telescope and Chandra X-ray Observatory.

Milky Way Skyscape over Mangaia
Credit: Tunc Tezel
This heavenly view of the Milky Way was taken in the South Pacific paradise of Mangaia, the most southerly of the Cook Islands. This image was chosen as one of the winners of the National Maritime Museum's Astrophotographer of the Year 2011 Contest.

Shot Through the Heart
Credit: ESO/Yuri Beletsky
Three of the four 8.2-m telescopes forming ESO's VLT are seen dimly, with a laser beaming out from Yepun, Unit Telescope number 4. The laser points at the Galactic Center of the Milky Way, our galaxy. The bright object at center is Jupiter, while the other is Antares.

Paranal-mal Activity
Credit: ESO
The Milky Way shines in all its majesty, as well as the Magellanic Clouds on the right. Some of the docking stations for the Auxiliary Telescopes of the VLTI lie in the foreground.

The Milky Way over the Isle of Sark
Credit: Martin Morgan-Taylor
Stargazers on the Isle of Sark, in the Channel Islands off the coast of England, enjoy the wonder of the Milky Way.

World's Largest Milky Way Image Unveiled
Credit: NASA/JPL-Caltech/Univ. of Wisconsin
A section of the largest image of the Milky Way ever created. It was stitched together from 800,000 individual infrared images taken by NASA's Spitzer Space Telescope.

Are the Stars Out Tonight?
Credit: ESO/Y. Beletsky
Wednesday, April 6, 2011: In Chile's Atacama Desert, the Large and Small Magellanic Clouds — satellite galaxies of our own — glow brightly at the left. The Milky Way, our galaxy, appears brightly on the horizon, while the European Southern Observatory's Very Large Telescope stands at the right.  ~Tom Chao

Milky Way Canary Islands
Credit: Terje Sorgjerd (
A still from a time-lapse video made by photographer Terje Sorgjerd of the night sky as seen from the Canary Islands.

Exiled Stars: Milky Way Boots Members
Credit: The SDSS Collaboration
A photos of one of the newfound stellar exiles.

Ancient Outburst of Milky Way's Black Hole Discovered
Credit: NASA/CXC/MIT/F.K. Baganoff et al.
This Chandra image shows our Galaxy’s center. The location of the black hole, known as Sagittarius A*, or Sgr A* for short, is arrowed. Also marked on this image are newly discovered large lobes of multimillion-degree gas that extend for dozens of light years on either side of the black hole.

New Photos of Milky Way From New Space Telescope
Credit: ESA and the SPIRE & PACS consortia
This composite image of star-forming gas clouds in the Milky Way was taken by the recently launched Hershel telescope, and released Oct. 2, 2009.

New Views of Our Milky Way Revealed
Credit: Stephane Guisard
This image, showing the center of the Milky Way, from the constellation Sagittarius to the constellation Scorpius, was taken by amateur astronomer and astrophotographer Stephane Guisard.

'Downtown' Milky Way
Credit: NASA/JPL-Caltech
A view from the bustling center of our galactic metropolis. Spitzer Space Telescope offers us a fresh, infrared view of the frenzied scene at the center of our Milky Way, revealing what lies behind the dust.

Credit: Canada-France-Hawaii Telescope/Coelum
Stars in the Milky Way.

Credit: NASA/CXC/Caltech/M.Muno et al.
This set of Chandra images shows evidence for a light echo generated by the Milky Way's supermassive black hole, a.k.a. Sagittarius A* (pronounced "A-star").

Milky Way's Galactic Center
Credit: NASA/JPL-Caltech/ESA/CXC/STScI.
A multi-wavelength image of the Milky Way's center. It is towards the galactic center where the highest number of stars and rocky planets reside, but also where the most supernovae occur.

Cosmic Finger Taps Our Galaxy's Shoulder
Credit: John Rowe Animations
The leading arm of gas streaming from the Magellanic Clouds is piercing the disk of the Milky Way.

Baby Stars Found in Galactic Center
Credit: NASA/JPL Caltech/S. V. Ramirez (NExSCI/Caltech)
The yellow circles show the young stars that were detected in the chaotic environment at the Milky Way's center.

Milky Way over Lake Superior
Credit: Shawn Malone
Skywatcher Shawn Malone sent in this photo of the Milky Way taken during the weekend of April 28-29, 2012, from the shore of Lake Superior. She writes: "The Milky Way was eye poppingly bright."

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