Can you see the aurora in Japan?
When people hear that, they usually think, “I bet you need expensive equipment like an astronomical telescope to see it, right?”
But surprisingly, there are several records of the aurora being observed with the naked eye in Japan. What’s more, these weren’t the curtain-like displays we usually see in photos; they were described as fan-shaped lights spreading across the sky.
This rare phenomenon is called the “low-latitude aurora,” and it has been observed in Japan numerous times throughout history.
- The Answer is “Low-Latitude Aurora”
- “Sekki” in Ancient Japanese Texts: The Nihon Shoki and Meigetsuki
- The Science Behind the Fan Shape: The Geometry of Low-Latitude Aurora
- Sound of the Northern Lights
- Why We Know the Meigetsuki Record Was the Aurora
- Can Modern Japan See the Aurora?
The Answer is “Low-Latitude Aurora”
Galileo Galilei is often credited with naming the aurora in a paper published in 1619. However, records of the aurora exist long before that.
In ancient Greece and Rome, aurora sightings were recorded as far back as the 5th century BC by famous figures like Hippocrates and Aristotle.
The latitudes of ancient Greece and Italy are roughly the same as those of Japan’s Hokkaido and Tohoku regions. This shows that the aurora was observed even in these lower latitudes, though it was a rare event. In China, the oldest record dates back to the 26th century BC.
Auroras seen at these lower latitudes are called low-latitude auroras.
“Sekki” in Ancient Japanese Texts: The Nihon Shoki and Meigetsuki
The oldest record of the aurora in Japan dates back to the Nihon Shoki (The Chronicles of Japan).
一二月の庚寅の朔に、天に赤気有り。長さ一丈余なり。形雉尾に似れり。
（Translation: On the first day of the twelfth month, there was a sign of a Sekki (Akaki shirushi) in the heavens. It was about ten feet in length and resembled the tail of a pheasant.）
『日本に現れたオーロラの謎』（片岡龍峰 2020）内の『新編日本古典文学全集日本書紀（２）』引用文より
The “Sekki” recorded here is believed to be the aurora. The description of its shape resembling a pheasant’s tail is a wonderfully unique Japanese observation!
Furthermore, the Meigetsuki (The Record of the Clear Moon), a diary from the Kamakura period written by the famous poet and compiler of the Hyakunin Isshu, Fujiwara no Teika, contains a clearer description of what is thought to be the aurora:
一二〇四年二月二一日、晴れ。日が暮れてから北および北東の方向に赤気が出た。その赤気の根元のほうは月が出たような形で、色は白く明るかった。その筋は遠くに続き、遠くは火事の光のようだった。白いところが五箇所あり、赤い筋が三、四筋。それは雲ではなく、雲間の星座でもないようだ。光が少しも陰ることのないままに、このような白光と赤光が入り混じっているのは不思議なうえにも不思議なことだ。恐るべきことである。
（February 21, 1204, Clear. After sunset, a Sekki appeared in the north and northeast. The base of the Sekki was shaped like the rising moon, and the color was white and bright. The streaks extended far into the distance, looking like the light of a distant fire. There were five white sections and three or four red streaks. It did not seem to be a cloud, nor was it a constellation between clouds. It is a mystery upon a mystery that such a mix of white and red light is present with no shadows whatsoever. This is a frightening thing.）
『日本に現れたオーロラの謎』（片岡龍峰 2020）
The red streaks spreading across the sky were vividly described as looking like a distant fire.
A drawing of this “Sekki” in the Edo period book Hoshikai (Star Interpretation) shows that the phenomenon was indeed fan-shaped.
The Science Behind the Fan Shape: The Geometry of Low-Latitude Aurora
The fan-shaped appearance of low-latitude auroras, like those recorded in the Meigetsuki, is a direct consequence of the Earth’s magnetic field geometry at mid-latitudes (like Japan).
- High Latitudes (e.g., Finland): The magnetic field lines are concentrated and nearly vertical, causing the familiar curtain-like or arc shape seen in photos.
- Mid-Latitudes (e.g., Japan): The field lines are more spread out and slanted (oblique). When a powerful geomagnetic storm occurs, the light emitted along these slanted field lines appears to the observer as numerous, parallel, tall, and thin vertical streaks. This specific morphology creates the distinctive fan or pheasant tail shape.
The analysis of the Kyoto record suggests this exact phenomenon: “The fine, tall vertical streaks of the aurora appeared in large numbers at equal intervals, spreading almost to the zenith of Kyoto and seeming to overwhelm the observer.”
Sound of the Northern Lights
Another ancient document, the Enkōan Zuikan Zue, contains this fascinating record:
高き所に登りてみれば赤気のうちに物の煮ゆるか音聞ゆ
（When I climbed to a high place, I heard a sound like something boiling within the Sekki.）
There are also indigenous Sámi traditions in Northern Europe that speak of a hissing or crackling sound emanating from the aurora. If this historical Japanese description truly refers to the sound of the aurora, it’s a truly remarkable connection!
Why We Know the Meigetsuki Record Was the Aurora
The aurora is caused by the solar wind (plasma particles from the sun) colliding with Earth’s atmosphere. The explosive eruptions of solar wind originate from sunspots on the sun’s surface. The larger the sunspot, the stronger the solar wind that reaches Earth, resulting in a brighter aurora.
On the very same day that the “Sekki” was recorded in the Meigetsuki (February 21, 1204), a record in China stated:
一二〇四年二月二一日太陽の中にことごとく黒点がありナツメのように大きい。
（On February 21, 1204, the entire sun was covered in sunspots as large as jujube fruits [small apples].）
Typical sunspots are often compared to sesame seeds, so a sunspot the size of a jujube fruit suggests a historically rare, colossal solar event.
This makes it extremely likely that the “Sekki” described in the Meigetsuki was a low-latitude aurora triggered by the powerful solar wind from this giant sunspot.
Can Modern Japan See the Aurora?
By analyzing these historical records, we can determine the two main opportunities for us to see the aurora in Japan today:
1. Wait for Solar Activity to Peak
Solar activity becomes active in roughly an 11-year cycle. The most recent peak is expected to be between 2023 and 2025. Auroras have already been observed in Hokkaido during this period (according to the Rikubetsu Space and Earth Science Museum website).
Historically, there are records of auroras being seen as far south as Tokyo about once every 100 years. The next chance might not be too far off!
2. Wait for Earth’s Magnetic Field to Weaken
If Earth’s magnetic field weakens, the latitude at which the aurora can be seen drops.
Currently, Earth’s magnetic field is gradually weakening. At this rate, some theories suggest that Japan could be within the auroral zone in about 700 years!
This means that if you can somehow manage to live for a few more centuries, you’ll be able to easily see the aurora right here in Japan! That’s amazing!
…What, impossible? (ﾟ∀ﾟ)
What do you think of this story connecting Japanese history and science with the aurora?
Complete Aurora Borealis Guide
Reference
- 『オーロラの物理学入門』小口高 2010 名古屋大学太陽地球環境研究所
- 『日本に現れたオーロラの謎』片岡龍峰 2020 化学同人
- 『雉尾攷―日本書紀にみる赤気に関する一考察』片岡 龍峰ほか 2020 総研大文化科学研究 第16号
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