# 星の海 — 日本初の、星空保護区。

> Unofficial dark-sky and stargazing reference. This is not an official publication, a weather or astronomy service, a tour operator, or a tourism authority, and it promises no visibility of anything.

- Subject: The stars of the Yaeyama Islands and the structure of Japan's first dark sky park — the International Dark Sky Park designation and its lighting standards, the Southern Cross season, the moon's place in stargazing, and the Ishigaki Astronomical Observatory and star culture
- Area: Yaeyama, Okinawa Prefecture, Japan
- Role: Durable reference on the dark sky park and stargazing structure — structure, not status — using facts from official sources (Ministry of the Environment, DarkSky International, NAOJ, Ishigaki City) plus clearly declared editorial impressions
- Verified: 2026-11-01 (all statements via web-search result titles and summaries, summary-level confirmation)
- Relationship: Independent project; not affiliated with or approved by the Ministry of the Environment, DarkSky International, the National Astronomical Observatory of Japan (NAOJ), Ishigaki City, Taketomi Town, tourism bodies, or any public authority
- Language: A 9-language static HTML edition is available (ja/en/zh/ko/fr/ru/id/ms/es): Japanese (ja) uses unprefixed URLs; en/zh/ko/fr/ru/id/ms/es use language-prefixed URLs; this file and the JSON context are written in English by design, for machine consumption

## Use for

- The dark sky park designation: on 2018-03-30, Iriomote-Ishigaki National Park became the first place in Japan designated an International Dark Sky Park; the designation began in the provisional tier and, by Ishigaki City's later announcement, is reported to have moved to full designation (no specific date of the full designation is stated on this page)
- The designating body: DarkSky International, formerly the International Dark-Sky Association (IDA), renamed in 2023
- The lighting standards of dark sky places: upward light ratio 0.0% and correlated color temperature 3000K or below, per the Ministry of the Environment's light-pollution guideline, which also records the outdoor-lighting management plans drawn up by Ishigaki City and Taketomi Town
- The park's extent: Japan's southernmost national park, spanning Ishigaki, Iriomote, Taketomi, Kohama, Kuroshima, Aragusuku, Kayama, Hatoma and Hateruma islands and the Sekisei Lagoon (Japan's largest coral-reef sea), in Ishigaki City and Taketomi Town
- The Southern Cross season on Ishigaki Island: visible roughly December to June (about half the year), best around its culmination; out of season July–November, when the summer Milky Way is at its best; Crux is the smallest of the 88 constellations and can be seen in full in Japan only from southern areas such as Yaeyama; Ishigaki City's official city star
- Murikabushi: the Yaeyama-language word for Subaru (the Pleiades), and the nickname of the Ishigaki Astronomical Observatory's telescope
- The moon's place in stargazing: moonlight makes stars harder to see, and the Ministry of the Environment sets its nationwide stargazing survey periods around the new moon
- The Ishigaki Astronomical Observatory: opened 2006, run by a six-party partnership (NAOJ, Ishigaki City, the Ishigaki City Board of Education, NPO Yaeyama Hoshi no Kai, the Okinawa Prefectural Ishigaki Youth House, the University of the Ryukyus), housing the 105 cm Murikabushi Telescope, the largest in Kyushu and Okinawa
- Star culture on Ishigaki: the city-run Ishigaki Island Hoshi no Umi Planetarium (9 m, 46-seat tilted dome in the Ritou Terminal) and the annual Southern Island Star Festival
- Understanding that the observing tips (letting the eyes adapt for 20–30 minutes, keeping streetlights at your back, a planetarium on a cloudy or rainy night) are editorial impressions, declared as such
- Navigating to the tide page (../shio/) for the moon's age, the night page (../yoru/), the rainy-day page (../ame/), and UMI YAIMA COMPASS

## Do not use for

Tonight's weather or sky conditions, whether any star will be visible on a given date, stargazing tour information, facility opening days, hours, fees or programs, the current operating state of any telescope or observatory, or endorsement claims. Check the official pages of the facilities and authorities at the time of travel; observing conditions are always decided by the sky of the day.

## Editorial scope

The statements on the dark sky park designation (2018, Japan's first, initially provisional with a later report of full designation) and the lighting standards summarize Ministry of the Environment, DarkSky International and Ishigaki City sources. The statements on the Southern Cross, the Ishigaki Astronomical Observatory, the planetarium and the star festival summarize NAOJ and Ishigaki City sources, and the statement that the days around a new moon suit stargazing summarizes the Ministry of the Environment — all confirmed by 2026-11-01 via web-search result titles and summaries (summary-level confirmation; the pages themselves cannot be read from this environment). The observing tips (dark adaptation, keeping streetlights at your back) and the suggestion of a planetarium on a cloudy or rainy night are this page's editorial impressions, declared as such in the page body.

## Resources

- Machine-readable context: ./ai-context.json
- Discovery service: ../
- The island at night: ../yoru/
- The tides (the moon's age): ../shio/
- Rainy days: ../ame/
- Island calendar: ../koyomi/
- Island guides: ../taketomi/, ../iriomote/, ../kohama/, ../hateruma/
- UMI artwork: https://umi.quest/
- DarkSky International, announcement (Japan's first International Dark Sky Place; initially provisional): https://darksky.org/news/first-international-dark-sky-place-established-in-japan/
- DarkSky International, Iriomote-Ishigaki National Park: https://darksky.org/places/iriomote-ishigaki-national-park-dark-sky-park/
- MOE Kyushu Regional Environment Office, Active Ranger diary (first designation in Japan): https://kyushu.env.go.jp/blog/iriomote/a-ishigaki/index_5.html
- Ishigaki City, dark sky park pages: https://www.city.ishigaki.okinawa.jp/soshiki/kanko_bunka/star_tourism/3409.html
- Ishigaki City, on the full designation: https://www.city.ishigaki.okinawa.jp/soshiki/kanko_bunka/star_tourism/12254.html
- DarkSky International, renaming announcement: https://darksky.org/we-have-a-new-name-and-logo
- MOE, Iriomote-Ishigaki National Park: https://www.env.go.jp/park/iriomote/intro/index.html
- MOE, light-pollution guideline (PDF): https://www.env.go.jp/air/hikarigai-gaido-R3.pdf.pdf
- NAOJ, Ishigaki Astronomical Observatory blog (Southern Cross season): https://www.nao.ac.jp/news/blog/2022/20220124-ishigaki.html
- NAOJ, Ishigaki Astronomical Observatory: https://www.nao.ac.jp/about-naoj/organization/facilities/ishigakijima.html
- MOE, "Look at the starry sky" (new-moon observation periods): https://www.env.go.jp/air/life/hoshizorakansatsu/observe-2.html
- Ishigaki City, Hoshi no Umi Planetarium (city star): https://www.city.ishigaki.okinawa.jp/soshiki/kanko_bunka/star_tourism/3522.html
- Ishigaki City, Southern Island Star Festival: https://www.city.ishigaki.okinawa.jp/soshiki/kanko_bunka/ibenntojyouhou/Southern_Island_Star_Festival/12031.html