Scientists in 2021 observed the inner layers of a massive star in the Milky Way during a rare explosion called supernova 2021yfj. The event was described as a breakthrough because the explosion exposed parts of the star usually hidden from study. The outer hydrogen and helium had already disappeared before the collapse, and even deeper layers of silicon and sulfur were stripped away. This unusual case allowed researchers to examine the order of elements, showing lighter ones on the surface and heavier ones near the center. The study, published in Nature, was considered an epochal moment, as it confirmed long-standing theories about stellar structure and gave scientists a new way to understand how stars end their lives. Experts said the results gave credible and reliable evidence that strengthened established scientific ideas and offered an insightful perspective on stellar life cycles.

The discovery also created new questions about how the star lost its layers. Experts debated whether the removal was caused by violent activity in its last stages or by the pull of a twin star. The study gave a lucid confirmation of earlier models, but it also introduced conundrums that remain unresolved. Astronomers warned that the chance to see such a clear event may not appear again soon, since explosions of this type are rare. Still, the research is expected to play a seminal role in learning how exploding stars spread elements that later form planets and life. Specialists described the finding as a monumental step in tracing the dynamic and significant history of stars and their evolution.