The images below show how galaxies similar in mass to our home galaxy, the Milky Way, evolved over time. The images taken by the NASA/ESA Hubble Space Telescope reveal that Milky Way-like galaxies grow larger in size and in stellar mass over billions of years. These images are part of the most comprehensive multi-observatory galaxy surveys yet. Stretching back in time more than 10 billion years, the census contains nearly 2 000 snapshots of Milky Way-like galaxies.
For an explanation of the z values quoted below, see this Redshift article.
11.3 Billion Years Ago
The image above reveals a compact, youthful galaxy as it looked 11.3 billion years ago, when our Universe was only about 2.5 billion years old. The bluish-white glow reveals that the fledgling galaxy is undergoing a wave of star birth, as its rich reservoir of gas compresses under gravity, creating myriad stars.
10.9 Billion Years Ago
10.3 Billion Years Ago
At 10.3 billion years ago, the firestorm of star birth is reaching its peak. The stellar “baby boom” churned out stars 30 times faster than the Milky Way does today. The galaxy’s yellowish colour most likely highlights ongoing star formation that is being obscured by dust and gas.
8.9 Billion Years Ago
Eventually, the galaxies exhaust their star-making gas. The galaxy at 8.9 billion years ago (image above) has developed a spiral shape, and the oldest stars reside in its central region.
6.1 Billion Years Ago
By 6.3 billion years ago this similar galaxy had grown even larger. The galaxy was dominated by mostly older stars, which can be seen in its reddish appearance.
3.1 Billion Years Ago
At 3,1 billion years ago this galaxy had clearly visible spiral arms dotted with clouds of gas lit by newly formed open star clusters.