Carved pumpkins and spooky costumes are the visual aids that remind us Halloween is here, but few people probably remember the chilling geomagnetic disruptions caused by a green aurora that lit up the skies in late 2003. Trick or treat! How the atmosphere terrorized Halloween  According to redOrbit, the phenomenon, known colloquially as a "geomagnetic storm", swept across the heavens on Oct. 31, 2003 and brought with it an array of unexpected disturbances. For example, GPS systems, which utilize satellite technologies to assist with ground-based navigation, were eerily disabled as their supportive technologies were taken offline. Consumers and military personnel alike were suddenly left in the dark as, slowly but surely, the force of the storm brought their systems offline. As if these blackouts weren't scary enough, modes of communication were also compromised. Devices that utilize radio waves to transmit signals between airlines became so impaired that planes traveling near the poles had to adjust or cancel their routes. Additionally, as a cursory point of perspective, redOrbit noted that scientists tracking the phenomenon had no idea what to expect. "In other words, the storm was so large that it could be measured with a simple compass," wrote the U.S. Geological Survey in a blog post about the event. What causes these events? Fortunately, The Washington Post reported that magnetic events of this caliber do not occur very often. According to the news source, coronal mass ejections (CME) or solar storms are the result of an influx of sun activity that produces a series of flares. Essentially, magnetic energy erupts from the interior of the sun and creates sunspots that eventually erupt. HowStuffWorks states that Earth's electromagnetic fields react similarly to what happens when strong magnets, such as cube magnets or bar magnets, are placed next to weak ones. Basically, if the power of the CME were any stronger, the overwhelming power of the sun's solar flares could have changed Earth's magnetic fields in unpredictable ways because the weaker field will always align with the stronger. The Washington Post reported that after the worst of these flares were behind us, scientists who were tracking the activity determined that the brunt force and volume of the flares could have ended life on Earth as we know it. Although no physical damage befell the planet, satellites in orbit that weren't destroyed required considerable repairs. Additionally, redOrbit noted that the long-term effects of the event are yet undetermined. Discover More With Apex Magnets Even years later NASA refers to this geomagnetic storm as one of the scariest, don't believe us? Watch the video about the Halloween solar storm for yourself! Want to stay up-to-date on the latest magnetic discoveries? Sign up for our newsletter to get these stories and more sent straight to your inbox each month.