Aurora Brought by the First Solar Flare in 20 Years Observed Across Japan | Release #174
cover image by yui
When you think of auroras, you might imagine them as a rare phenomenon only visible in places like Antarctica, the Arctic, North America, or Northern Europe. Many tourists travel from distant countries to these regions just to catch a glimpse of this breathtaking spectacle.
But did you know that these mystical auroras can actually be observed in Japan?
Reports of Successful Aurora Observations Across Japan
On May 10, 2024, the strongest solar flare in 20 years occurred. High-energy particles were released towards Earth, causing a geomagnetic storm that disrupted the Earth's magnetic field, leading to power grid failures and radio communication outages.
The solar radiation reached Earth on the 10th, with effects lasting until the 12th. As a result, vibrant auroras were visible in skies around the world. In Japan, particularly in Hokkaido, reports of successful aurora observations poured in.
Mechanism of Low-Latitude Auroras
The basic mechanism of low-latitude auroras is the same as those occurring in high-latitude regions. Solar winds cause a large magnetic disturbance known as a 'geomagnetic storm', leading to auroras larger than usual. This allows them to be seen from low-latitude areas like Japan, where they are usually not visible. A significant difference from typical auroras is their red color. Auroras change color based on altitude, and the red part visible from low latitudes is above 200 km in altitude.
Auroras in Japanese Historical Records
Low-latitude auroras observed in Japan can also be confirmed from historical records. During the Edo period, the diary of the Higashihakura family in Kyoto included illustrations of auroras, showing the amazement of people at the time. Auroras, known as 'red spirits', have been reported from the era of the Nihon Shoki to the Edo period, with reports of the northern sky glowing red in Kyoto and Edo.
Even in modern times, reports of the northern sky turning red in Hokkaido have been mistaken for wildfires, prompting fire trucks to be dispatched.
Chance to See Auroras in Japan
The chance to see visible auroras in areas like Hokkaido is said to occur roughly once every 11 years. This is related to the 11-year solar cycle, with auroras more likely during periods of high solar activity. The next opportunity to observe auroras in Japan will be in 2035. Although still some time away, those who missed this chance should not miss the opportunity to witness this natural wonder next time.
