Observing the Universe with a World-Class Telescope
The 150-cm Reflecting Telescope
One of the greatest attractions of Gunma Astronomical Observatory is its 150-centimeter reflecting telescope, housed inside an 11-meter dome.
As a telescope that can be viewed directly through the eyepiece, it is among the largest of its kind in the world. It uses a Ritchey–Chrétien optical system and is also a sophisticated research instrument capable of observations ranging from visible light to near-infrared wavelengths.
During nighttime observing sessions, observatory staff explain the objects being viewed while visitors observe nebulae, star clusters, planets, and other celestial bodies.
A star that appears to the naked eye as nothing more than a tiny point can reveal remarkable detail through the telescope. During the peak of major meteor showers, special observing events are also held, allowing visitors to lie on the grass and watch the sky while waiting for shooting stars.
Advanced Observation Equipment, Research, and Education
A 65-centimeter reflecting telescope is installed inside the observatory’s 7-meter dome. It is equipped with sophisticated instruments, including a cooled CCD camera and a spectrograph.
On the roof of the main building, a solar telescope allows visitors to observe sunspots, prominences, and H-alpha images. The facility’s ability to display a directly projected image of the Sun approximately 1 meter in diameter is particularly unusual in Japan.
The observing building also contains several smaller telescopes, including a 15-centimeter refracting telescope, as well as portable telescopes. Visitors who complete the required training course can even make exclusive use of the 65-centimeter telescope.
The observatory actively conducts joint observations with universities and research institutions in Japan and abroad. It also supports educational programs and astronomy lectures, giving it an important role not only as a public attraction but also as a research and educational institution.
Precision Observations with a High-Sensitivity CCD Camera
The 65-centimeter telescope is equipped with a high-sensitivity cooled CCD camera that can efficiently detect extremely faint light.
The cooling system reduces electronic noise, making it possible to photograph faint nebulae and distant galaxies. The images collected by the camera can be analyzed by computer and used for precise measurements, such as monitoring changes in the brightness of variable stars and tracking the movement of asteroids.
Analyzing the Composition of Stars with a Spectrograph
A spectrograph is an instrument that separates light from a celestial object according to its wavelength.
By examining these spectra, astronomers can investigate properties such as a star’s temperature, chemical composition, and velocity. For example, the spectrum can reveal the presence and relative abundance of elements such as hydrogen and helium. It can also provide information about whether an astronomical object is moving toward or away from Earth.
Educational programs use actual observations of light spectra to introduce visitors and students to the fundamentals of astrophysics.
The Solar Telescope and Special Filters
The solar telescope on the roof of the main building is equipped with special filters, including an H-alpha filter.
These filters make it possible to safely observe features such as sunspots, solar prominences, and solar flare activity. The projected image of the Sun, approximately 1 meter in diameter, is particularly impressive and provides a vivid sense of the dynamic activity taking place on our nearest star.
Digital Control and Automatic Tracking
The large telescopes are equipped with computer-controlled automatic tracking systems. These systems compensate for the Earth’s rotation and allow the telescopes to follow celestial objects accurately across the sky.
This technology supports long-exposure photography and precise photometric observations. Observation data can also be stored and shared through networks, supporting collaborative research with astronomical institutions in Japan and overseas.
Portable Telescopes and Hands-On Observation
Portable telescopes and binoculars are also used during public observing sessions.
Hands-on programs allow participants to operate some of the equipment themselves while observing the Moon, planets, and other celestial objects. These activities are particularly popular with children, who can learn how telescopes work while developing a deeper interest in astronomy.
Outdoor Monuments and a Surreal Landscape
The grounds feature reproductions of historic astronomical structures from around the world. These include a sundial inspired by the Jantar Mantar, an astronomical observatory complex built in India during the 18th century, and a stone circle modeled after Stonehenge in Britain.
These outdoor installations allow visitors to explore the history of astronomy and imagine how people in earlier eras observed the movement of the Sun and stars.
The distinctive scenery has also made the observatory a popular filming location for special-effects television programs, dramas, movies, and music videos. The combination of astronomical structures, open landscapes, and mountain scenery creates an unusual and almost otherworldly atmosphere.
A Walking Trail Through the Seasons
To reduce light pollution around the observatory, the parking area is located approximately 600 meters from the main building. Visitors walk along a trail with an elevation difference of approximately 70 meters to reach the observatory.
Although the route includes an uphill section, it is well maintained and takes approximately 10 minutes for an adult at a normal walking pace.
The walk itself is part of the experience. Visitors can enjoy fresh green foliage in spring, sunlight filtering through the trees in summer, colorful autumn leaves, and snowy scenery in winter.
Comfortable walking shoes are recommended, particularly when visiting during colder or snowy periods.
Facilities and Visitor Information
Main Building
The first floor of the main building contains the reception area, a gift shop, and a video hall with seating for approximately 100 people. The hall is used for astronomy lectures, educational programs, and school visits.
On the second floor, visitors can learn about astronomy through exhibition panels explaining stellar evolution, models of astronomical instruments, and displays introducing the analysis of observational data.
Opening Hours and Admission
Opening hours vary depending on the season. The observatory offers daytime visits to the facilities as well as nighttime astronomical observing sessions.
Admission is approximately ¥300 for adults and ¥200 for university and high school students, while junior high school students and younger children can enter free of charge. Visitors can also re-enter on the same day.
An Unforgettable Encounter with a Sky Full of Stars
The clear night sky above Takayama Village offers a memorable experience for anyone accustomed to the bright lights of a city.
Waiting for meteors while lying on the grass, looking at a distant nebula through a giant telescope, or seeing sunspots on the surface of the Sun can all provide a sense of wonder that is difficult to experience in everyday life.
The observatory is also conveniently accessible by car, approximately 25 minutes from the Shibukawa-Ikaho Interchange and about 20 minutes from the Tsukiyono Interchange of the Kan-Etsu Expressway.
For travelers exploring Gunma Prefecture, Gunma Astronomical Observatory offers a unique combination of science, nature, and breathtaking views of the universe. Visit the “Village of Falling Stars” and experience the wonder of the night sky from one of Gunma’s most distinctive astronomical destinations.