Evolution of the Milky Way: ‘Movie’ captures eight billion years of change

illustration of Milky Way galaxy

This illustration depicts a view of the night sky from a hypothetical planet within the youthful Milky Way galaxy 10 billion years ago. The heavens are ablaze with a firestorm of star birth. Glowing pink clouds of hydrogen gas harbor countless newborn stars, and the bluish-white hue of young star clusters litter the landscape. The star-birth rate is 30 times higher than it is in the Milky Way today. The Sun, however, is not among these fledgling stars. as it will not be born for another 5 billion years. (Illustration: NASA, ESA and Z. Levay / STScI.)

Astronomers have pieced together the evolution of the Milky Way in pictures, using data from telescopes in space and on Earth, and compiling thousands of snapshots taken of similar galaxies. Their work is published in the April 10 issue of The Astrophysical Journal.

Led by a Texas A&M associate professor of physics and astronomy, Casey Papovich, the international team of two dozen astronomers spent a year studying distant galaxies. “As we look at distant galaxies, we see how they looked when their light left for Earth,” Papovich said. “Because the galaxies are billions of light-years distant, we can see how they looked billions of years in the past.”

Based on information form more than 24,000 galaxies, the team eventually developed a sequence to represent how the Milky Way is likely to have evolved, in effect creating a “movie” of the Milky Way’s life from youth to middle age (see image at bottom).

Among the team’s findings:

* The Milky Way experienced its most rapid phase of growth between 9.2 and 10 billion years ago, churning out new stars at a spectacular rate that was about 30 times what it is today.

*The Sun is among those more recently formed stars, born roughly 5 billion years ago at a point when star formation within the Milky Way had slowed to a comparatively cosmic crawl that continues today. The Sun’s somewhat fashionably late appearance actually may have been fortuitous, fostering the growth of the planets within our solar system.

The team’s multi-wavelength study was supported by funding from NASA and the National Science Foundation, The international collaboration included Leiden University in Holland, Swinburne and Macquarie in Australia, Carnegie Observatories in Pasadena, Calif. Texas A&M hosts the survey’s website and data.

More at the College of Science

An animated version of the Milky Way Galaxy's life story.
An animated version of the Milky Way Galaxy’s life story.