Without the Sun, none of us would actually be here, so we should be pretty thankful that it exists at all. That being said, tumbling through space around a star isn’t always a walk in the park, especially when that star has a temper.

Every once in a while, the Sun gets restless and spews solar material out into space at incredibly high speeds. These events, coronal mass ejections, follow solar flares and result in what we experience on Earth as a solar storm. As LiveScience reports, a new investigation into a particularly brutal solar storm back in 1972 has revealed just how devastating such an event can be, and explains how that particular event had explosive consequences here on Earth.

The research, which was published in the journal Space Weather, sheds some light on a little-reported side effect of a solar storm that hit the Earth on August 4th, 1972. The paper explains that when the solar ejecta reached Earth, it actually caused bombs to spontaneously explode.

Digging through Vietnam War-era archives from the U.S. Navy, the researchers discovered that long-forgotten sea mines which were placed during the conflict actually reacted to the magnetic effects of the solar storm as it hit the planet. Dozens of the mines, designed with magnetic detonators that are set off when a ship passes close by, were triggered by the storm.

“In researching these events we determined that the widespread electric‐ and communication‐grid disturbances that plagued North America and the disturbances in southeast Asia late on [August 4th] likely resulted from propagation of major eruptive activity from the Sun to the Earth,” the paper reads.

The weapon’s designers couldn’t have possibly imagined that their underwater mines would be susceptible to magnetic weirdness arriving from the Sun, but that doesn’t change how scary this may have been for anyone within earshot.