Diamond Fuji

About a month ago, I saw a short article on the Asahi Shimbun about Diamond Fuji (ダイヤモンド富士). I had never heard of the term Diamond Fuji before. The article had a very pretty accompanying photo of the rising sun—a big orb of deep, radiant yellow and orange glowing in the early morning air—just cresting Mt. Fuji, whose peak was just about symmetrically silhouetted against the sun's disk from the camera's perspective. The photo was taken on the early morning of July 9, 2013. This scene, in which the rising or setting sun aligns with Mt. Fuji's peak, as seen from certain vantage points, is what is referred to as Diamond Fuji.

At first, I just stared at the photo, wondering what the significance was, and why the Asahi Shimbun, a major Japanese newspaper, was running an article on it. I was puzzled even after reading the Japanese article. Then, after a while thinking about it, I had my duh moment and realized that, from a certain vantage point around Mt. Fuji, which is located around 100 km (62 miles) southwest of Tokyo, such a scene, such a photo, was only possible on certain days of the year, at certain times of those days (around sunrise and sunset), and then again only if the weather allowed.

The photo in the article was taken by a Buddhist priest who was in Kawakami, Nara Prefecture, at an impressive distance of about 277 km (172 miles) southwest of Mt. Fuji, at an elevation of 1350 meters. He took the photo using a camera with a 300mm zoom lens.

Because the Earth revolves around the Sun, and the Earth's axis of rotation is tilted and not perpendicular to the orbital plane, the Sun's apparent path across the sky changes as the year progresses. The position where the Sun rises on the horizon, as observed from a certain location, moves predictably with the day of the year. Similarly, as seen from a certain vantage point around Mt. Fuji, the position where the Sun crosses behind Mt. Fuji on its way up or down marches with each day of the year. Since the Sun rises in the east and sets in the west, Diamond Fuji will occur sometime before sunset if you are located to the east of Mt. Fuji; if you are to the west, Diamond Fuji will occur sometime after sunrise. For these places, the window within which this special sight is visible opens twice a year. To get a glimpse of Diamond Fuji, one must be at the right place at the right time, with luck and the weather gods on one's side.

The ecliptic (the apparent path of the Sun on the sky), is bound on the north by the Tropic of Cancer, at a latitude of about 23.4°N, and on the south by the Tropic of Capricorn, at a latitude of about 23.4°S. (It is no coincidence that the axial tilt of the Earth is also about 23.4°.) Since Mt. Fuji's latitude is about 35.4°N, the Sun's path is always to the south of Mt. Fuji and never crosses Mt. Fuji's zenith. One window opens to Diamond Fuji at a time of year when the Sun is tracing a northerly path on the sky, and the other window opens at a time of year when it is tracing a southerly path.

Just a few of the popular places from which people try to catch a glimpse of Diamond Fuji are: Mt. Shichimen, located about 30 km (19 miles) west of Mt. Fuji in Yamanashi Prefecture; Lake Yamanaka, located to the east, at the base of Mt. Fuji in Yamanashi Prefecture; Lake Tanuki, located to the west, near Mt. Fuji in Shizuoka Prefecture; Mt. Takao, which is located in Tokyo, northeast of Mt. Fuji; and from the Tokyo Skytree and the Tokyo Tower.

So, the next time you visit Japan and find yourself in the vicinity of Mt. Fuji, find out if you're at the right place and time to catch a rare glimpse of Diamond Fuji.

If you'd like to share more information about Diamond Fuji, please feel free to leave your comments below.

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Japanese vocabulary

Here are the English definitions of some relevant Japanese words from the Asahi Shimbun article on Diamond Fuji:

• ダイヤモンド; diamond
• 富士山 [ふじさん] Mt. Fuji
• 奈良県 [ならけん] Nara Prefecture
• 撮る [とる] to take a photo
• 重なる [かさなる] to overlap (each other); to occur at the same time; to happen simultaneously
• 南西 [なんせい] southwest
• 川上村 [かわかみむら] Kawakami village
• 付近 [ふきん] neighborhood; vicinity; environs
• 撮影 [さつえい] photographing
• 早朝 [そうちょう] early morning
• 標高 [ひょうこう] elevation; height above sea level
• 北東 [ほくとう] northeast
• 空 [そら] sky; the heavens
• 映る [うつる] to be projected
• 山頂 [さんちょう] summit (e.g. mountain)
• 朝日 [あさひ] morning sun
• 捉える [とらえる] to capture
• 写真 [しゃしん] photograph; photo
• 挑戦 [ちょうせん] challenge; defiance
• 成功 [せいこう] success; hit
• 感服 [かんぷく] (arch) admiration; Well done!

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Note that the Asahi Shimbun website drops news stories after about one year, so links to their news stories will generally stop working one year after publication. Column articles seem to be retained, though. For how long, I don't know.

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