Opinion From Pune, the discovery of Alaknanda, Milky Way’s long-lost sibling

In the study of the cosmos, exceptions play a curious role. They start as challenges to established science, disruptions to theories astronomers worked years to arrive at. They push the frontiers of science, finding patterns behind the non-sequitur, often uncovering a hidden facet of the universe. For example, until 1998, scientists believed that cosmic expansion would slow down. But, in a challenge to gravity, they found out it was speeding up. The unknown force driving this abnormal behaviour was named dark energy, a widely studied phenomenon today. Even Earth, as NASA notes, is “a tiny, fragile exception in the cosmos”.

Since its launch in 2021, the James Webb Space Telescope (JWST) has unearthed many such exceptions, the most notable of which led scientists to the discovery that the universe formed much quicker than they originally thought. Scientists expected the earliest-formed galaxies to be irregularly shaped and unstable, turbulent. But in recent years, the JWST has recorded the existence of galaxies formed within 1.5 billion years after the Big Bang that were both stable and well-defined. This week, one of the earliest of these galaxies, and a “twin” of the Milky Way, was discovered by researchers in Pune, proving that “sophisticated structures were being built… much earlier than thought possible”. Alaknanda is a mature galaxy with two well-defined spiral arms wrapping around a bright central bulge. It is remarkably similar in structure to the Milky Way. These discoveries have kicked off a rethink of how the universe evolved.

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A challenge to the status quo, cosmic or otherwise, always arrives as an inconvenience. But in that irregular variable lie many answers. In trying to understand what stands out and apart, human beings may be able to understand both the universe and themselves a little bit better.