New images provide 'huge leap' in understanding the Milky Way's elusive past

Distant images of galaxies will help astronomers piece together our own Milky Way's evolution.

The galaxy ESO 364-G035 and its neighbours on photographic plates (left) compared to the the DESI Legacy Surveys from the 2010s. Source: Monash University
The galaxy ESO 364-G035 and its neighbours on photographic plates (left) taken in the 20th century, compared to the the DESI Legacy Surveys from the 2010s (right). Source: Monash University

Details in distant galaxies have come into focus after extraordinary improvements in satellite technology. New photographs taken by the Euclid wide-angle space telescope have left Australian astronomers excited about its ability to accelerate our understanding of how our own galaxy evolved.

The European Space Agency mission began just over a year ago, with a primary purpose of measuring the expanding universe and creating an improved atlas of the cosmos. But the high-resolution colour images it takes of far-off galaxies will also provide data to track how they form and change over billions of years.

Associate Professor Michael Brown from Monash University is excited about using the improvements in telescopic imagery because they will aid his own specialisation, galaxy evolution. For a comparison of how far things have developed, he’s shared a grainy photo taken on photographic plates in the 20th century, an improved image from the 2010s, and new digital colour visuals taken by Euclid.

“Hopefully this gives a sense of how much the data has improved over the past 40 years. It enables a huge leap in the science we can undertake,” he told Yahoo News.

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This new Euclid image is a major advancement in quality. Source: European Space Agency/Monash University
This new Euclid image is a major advancement in quality. Source: European Space Agency/Monash University

Although the image quality isn't as good as the ground-based Hubble and James Webb space telescopes, Brown believes Euclid outperforms them because its huge cameras can shoot larger areas.

He is particularly interested in the spacecraft’s ability to detect fine traces of the formation of new stars and galaxies – a stage in their life vastly different to the Milky Way formed 13 billion years ago and is fading.

It's by studying galaxies similar to our own, which are only two, five, or even 10 billion years old, that experts will be able to better understand how the Milky Way's elusive past may have unfolded. Because galaxies slowly change over billions of years, their evolution can’t be witnessed by humans — we've only existed for a few hundred thousand years.

Brown compares the process of comparing galaxies to the study of fossil records. “You can witness how a specific fossil changes over time, but you can track the common traits of different fossils across different times in history, and connect the dots together,” he said.

He added, “With Euclid data, we’re going to be able to study millions of galaxies, and although we can't see them evolve — the universe moves too slowly for that — we could statistically understand how galaxies are changing with time, by comparing similar populations of galaxies across the history of the universe.”

The Milky Way will eventually collide with the Andromeda galaxy, as it’s speeding towards us at 110 km per second. When this occurs, huge amounts of rocks, dust, asteroids and planets will be flung in different directions. The most likely outcome is that they will merge, but by this time, 4.5 billion years into the future, Earth will no longer be habitable.

“Astronomy is a curiosity driven science. It tells us about where we are in the universe, how we came about, how our place in universe came about,” Brown said.

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