A massive solar storm struck Earth 2,687 years ago. Here's why such events pose a threat to us today.

The Earth is constantly affected by solar storms, also known as geomagnetic storms. These occur due to increased solar activity, when a significant amount of radiation and charged solar particles reach our planet. Such storms can disrupt satellites in orbit as well as ground-based energy systems and communication networks. The more intense the solar storm, the greater the threat to our technological world. Using the annual rings of ancient trees, which act as time capsules, scientists have found evidence of a colossal solar storm known as one of the Miyake events. These phenomena are so rare that only 8 have been recorded in the last 14,500 years, with one of the most recent occurring between 664 and 663 BC, as researchers have determined. The study was published in the journal Communications Earth & Environment, reports Space.

According to the authors of the study, humanity is fortunate that the colossal solar storm occurred 2,687 years ago. If this latest known Miyake event were to happen today, it would have catastrophic effects on our technologically advanced world. It could lead to a complete shutdown of all forms of communication on Earth, potentially halting internet operations and disrupting most energy systems. In other words, it would be a disaster of global proportions.

The Miyake events are an extreme type of solar activity first identified by Japanese physicist Fusa Miyake in 2012. A defining characteristic of these events is a sharp increase in radioactive carbon isotopes on Earth, particularly carbon-14, which is found in the annual rings of trees.

Carbon-14 is a radioactive carbon isotope that forms in the atmosphere when solar radiation interacts with nitrogen. Ultimately, carbon-14 reacts with oxygen to form carbon dioxide, which then enters trees through photosynthesis.

Scientists meticulously studied individual annual rings from ancient wood samples collected from dead trees buried along riverbanks, as well as from logs excavated during archaeological digs. The main component of the wood, cellulose, was then burned to determine the radiocarbon content.

When scientists detect elevated levels of radiocarbon in tree rings, they compare it to increased levels of various isotopes, such as beryllium-10. The latter is found in ice cores extracted from glaciers and ice sheets. This serves as another time capsule.

Like carbon-14, beryllium-10 is formed in the atmosphere as a result of solar radiation and charged particles, and then it is deposited into ice along with precipitation.

The comparison of the two isotopes' levels indicated that a colossal solar storm struck Earth between 664 and 663 BC. It is believed that the last known Miyake events occurred between 774 and 775, as well as between 993 and 994 AD. Thus, the new research has uncovered an event that adds to the seven previously known ones.