Take a Cosmic Walk Around the Mitaka Campus of the National Astronomical Observatory of Japan
The National Astronomical Observatory of Japan (NAOJ) Mitaka Campus is located in Osawa, Mitaka City, where the rich nature of Musashino remains intact. For more than 100 years, the facility has played a central role in Japan’s astronomy research.
Numerous historical structures are dotted around the vast campus. Most of the architecture dates from the Taisho Period (1912–1926) and Showa Period (1926–1989) and are registered as the nation’s Tangible Cultural Property. Each building reflects Japan’s progress in the study of astronomy.
On the southern side of the main entrance, there is a small building called 20-cm Telescope Dome. It is the oldest building on the campus. The 20cm diameter refractor or telescope installed inside was first used to observe sunspots in 1938: a practice that continued for 61 years. Today, a solar observation event is held, mainly on Saturdays and Sundays, for the general public to enjoy the experience.
Roughly in the center of the campus lies the Repsold Transit Instrument Building. A transit instrument is a telescope that can rotate along the meridian (the line connecting north and south) and is used to measure precisely the time that astral bodies pass the meridian. Many valuable transit instruments are exhibited here including the Repsold transit instrument. It played an active role for positional observation of the moon, planets, and stars until 1962.
The 65cm Equatorial Refractor Telescope, which is housed in the Observatory History Museum, has the largest diameter of all refractor telescopes in Japan. Although it was used for astronomical photo observation and spectroscopic observation, its operation ended in March 1998 due to ageing of the device. Today, it is preserved as a monumental piece of the country’s astronomical history and continues to awe people who come to see it.
The Observatory History Museum has a wooden dome that was built to house a refractive telescope with a focal length of about 10m. Constructed with the assistance of a marine engineer, it is a very rare building. Many other interesting buildings can also be seen: the Solar Tower Telescope, which is a tower that functions as a telescope tube; the Old Library featuring scratched face tiles, which was a popular design during the early Showa Period; and the Gautier Meridian Circle Building whose beautiful semicircle roof reminds Japanese people of kamaboko (steamed fish cake).
On the Solar System Walk, the distance between the sun and planets is shrunk to one 14 billionth of its actual distance. Read the information panels featuring miniature planets to get a better feel for the solar system’s scale as you walk along the path.
A night-time astronomical observation session is held twice a month at the campus (reservation required). Observing the moon and planets using a telescope with 5,000 times the light-gathering power than the naked eye is an impressive experience that everyone should try. In addition, a special event called Mitaka Open House Day is held every October. The general public is invited to enter buildings and facilities that are usually off limits, listen to lectures by specialists, and participate in stargazing sessions. People’s interest in and understanding of the universe is sure to deepen at these events.
Please visit the NAOJ Mitaka Campus: a sanctuary of Japan’s astronomical observations. You can see both historical structures and the nature of Musashino, as well as participate in stargazing sessions by using the latest equipment, enabling you to feel closer to outer space.
National Astronomical Observatory of Japan Mitaka Campus
Address: 2-21-1 Osawa, Mitaka-shi
Open hours: 10:00–17:00, admission until 16:30. Closed on New Year holidays.
A tour guidebook is available in English, Chinese, Korean, Spanish, Japanese, and Braille.