A supernova is a dramatic event in which a star violently explodes towards the end of its life cycle. In a striking image captured by the Hubble Space Telescope, the supernova explosion of a star called SN 2014J in the galaxy M82 is showcased. This discovery, made by NASA Goddard, sheds light on the powerful forces at play in our universe.
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Recent research has put forth a theory suggesting that violent supernova explosions could have been responsible for two of Earth’s major mass extinctions, events that have puzzled scientists for centuries. These massive explosions occur during the final stages of a colossal star’s life, resulting in a tremendous release of energy and materials into space.
By studying the supernova rate of stars located within 65 light-years of our sun over the past 1 billion years, a research team has connected nearby stellar explosions to at least one, and possibly two, mass extinction events. The team’s calculations, part of a broader survey in the Milky Way galaxy using data from the European Space Agency’s Gaia telescope, indicated that Earth might have been impacted by 2.5 supernovas every 1 billion years.
Contrary to previous beliefs, the researchers, led by coauthor Nick Wright, found that the rate of supernovas affecting Earth may be lower than initially thought. This realization prompted the team to explore the potential correlation between supernovas and mass extinctions on Earth. The study, published in the Monthly Notices of the Royal Astronomical Society, suggests that these cosmic events could have played a role in shaping the planet’s biodiversity through cataclysmic events occurring over the past 500 million years.
These findings underscore the dual role of colossal stars in both creating and potentially destroying life, as emphasized by lead author Alexis Quintana. Supernova explosions not only introduce heavy chemical elements into space, which can foster the formation of new stars and planets, but they could also have devastating consequences if a planet, including Earth, is in close proximity to such an event.
While the research does not provide concrete evidence linking supernovas to mass extinctions, the team postulates that a supernova explosion could have contributed to the Late Devonian extinction event 372 million years ago and the extinction at the end of the Late Ordovician 445 million years ago. The team’s hypothesis suggests that a supernova might have damaged the ozone layer, leading to a series of events culminating in mass extinctions on Earth.
During the Late Devonian era, terrestrial life was flourishing for the first time, but this event saw the demise of early land plants and animals transitioning from water to land, along with various marine species. The Late Ordovician extinction event, characterized by a significant loss of 85% of species, occurred during a time when life primarily thr
“A possible occurrence close to Earth of such an explosion would result in glaciation, a phenomenon that is known to have happened in the past. Thus, it remains an open hypothesis without concrete evidence,” stated Mike Benton, a vertebrate paleontology professor at the University of Bristol in the UK. He emphasized the necessity of aligning historical events to demonstrate their correlation with mass extinctions. Benton, author of “Extinctions: How Life Survives, Adapts and Evolves,” highlighted the importance of developing methods to accurately date supernova explosions from ancient times.
Meanwhile, Paul Wignall, a paleoenvironments professor at the University of Leeds in the UK, acknowledged the interesting nature of the research suggesting a supernova-driven extinction. He emphasized the need for tangible evidence linking extinctions to supernovas, possibly through the presence of unique elements sourced from the explosions in sedimentary records.
In the realm of celestial events triggering mass extinctions, scientific evidence has confirmed at least one such occurrence. Approximately 66 million years ago, a city-sized asteroid collided with Earth near present-day Mexico, leading to the extinction of dinosaurs and numerous other species.
The discovery of the “iridium anomaly” in sedimentary rock following the end-Cretaceous extinction event provided crucial insights into the cause of this mass extinction. Initially met with skepticism, the presence of iridium in sediments was later confirmed in various locations worldwide, eventually leading to the identification of a large crater off the coast of Mexico’s Yucatan Peninsula.
While the iridium anomaly served as a compelling piece of evidence for the dinosaur extinction in 1980, similar markers are sought for potential supernova-driven extinctions, such as iron-60 or plutonium. Iron-60, a radioactive isotope not commonly found on Earth but produced in abundance during supernova explosions, could serve as a key indicator. Additionally, the measurement of ozone depletion in rocks and sediments might offer further insights.
Recent studies on mass extinction events have revealed a complex series of consequential factors, often initiated by massive volcanic eruptions. Wignall noted the challenge of integrating a supernova event into such scenarios, questioning its timing and impact within the context of cascading environmental crises.
The research team aims to raise awareness of the new supernova timescale they have established and address uncertainties surrounding extinction events. By emphasizing the significance of numerical data, the researchers hope to encourage further exploration and understanding in this field.
