Our sun has only been around for 4.5 billion years — which means it missed the cute early years of the Milky Way galaxy. If you were standing on a planet 10 billion years ago, when the Milky Way was relatively young, the night sky would have looked very different.
The above image is an artist's impression of the night sky on a planet in a young Milky Way-type galaxy, the way ours was 10 billion years ago. You can see "the sky are ablaze with star birth. Pink clouds of gas harbor newborn stars, and bluish-white, young star clusters litter the landscape," as NASA explains.
A new survey of young galaxies like our own shows that as these galaxies slow down making stars, they also stop growing as quickly in general. Which makes sense. NASA explains:
Astronomers don’t have baby pictures of our Milky Way’s formative years to trace the history of stellar growth so they studied galaxies similar in mass to our Milky Way, found in deep surveys of the universe. The farther into the universe astronomers look, the further back in time they are seeing, because starlight from long ago is just arriving at Earth now. From those surveys, stretching back in time more than 10 billion years, researchers assembled an album of images containing nearly 2,000 snapshots of Milky Way-like galaxies.
The new census provides the most complete picture yet of how galaxies like the Milky Way grew over the past 10 billion years into today’s majestic spiral galaxies. The multi-wavelength study spans ultraviolet to far-infrared light, combining observations from NASA’s Hubble and Spitzer space telescopes, the European Space Agency’s Herschel Space Observatory, and ground-based telescopes, including the Magellan Baade Telescope at the Las Campanas Observatory in Chile.
Here's a selection of Hubble Space Telescope snapshots, showing how galaxies similar to our own evolved over time:
Read a lot more about this in the NASA release.
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