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10 billion years ago, our sky was full of stars being born

10 billion years ago, our sky was full of stars being born

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Light pollution and city living mean that we don't often get to enjoy the full splendor of the night's sky. Ten billion years ago, however, it would have been hard to ignore. The image above shows how the night's sky would have looked 10 billion years ago during our galaxy's "baby boom" phase.

At the time, the Milky Way was producing stars at an phenomenal rate — 30 times faster than it is today. The pink clouds in the image are the interstellar nurseries of gas and dust, while the blue and white points of light are the newly formed stars. If this was a real picture, however, some of stars, newborn 10 billion years ago, would already be extinguished today.

astronomers made a cosmic growth chart by mapping other galaxies

The image itself is the result of a new census of the galaxy being published in The Astrophysical Journal and reported by NASA. To complete the survey, astronomers sifted through data on more than 24,000 galaxies, identifying those similar to the Milky Way, mapping their development in detail, and then estimating how our galaxy fits into this cosmic growth chart.

Six Hubble pictures show galaxies similar in size to our own during different stages in the development. (NASA/ESA/C. Papovich/H. Ferguson/S. Fabe)

The results show that the formation of our own sun came relatively late in the Milky Way's life — just 5 billion years ago. Being a late bloomer isn't all bad though. Scientists say that because our sun formed after the "baby boom" phase had finished, this meant there were more heavy elements like hydrogen and helium left over from stars that had already died. This provided the necessary fodder to construct our solar system's planets and, perhaps, life on Earth itself. The research also reinforces earlier theories that galaxies like ours start out as a clump of stars, before absorbing a large quantity of gas and exploding in seas of stars.

"This study allows us to see what the Milky Way may have looked like in the past."

"This study allows us to see what the Milky Way may have looked like in the past," said Casey Papovich, lead author on the study. "It shows that these galaxies underwent a big change in the mass of its stars over the past 10 billion years, bulking up by a factor of 10, which confirms theories about their growth. And most of that stellar-mass growth happened within the first 5 billion years of their birth."