Open Doors Day 2025 at the Astronomical Institute – Visitors Discover the Mysteries of the Cosmos

On Friday, June 27, 2025, the Astronomical Institute of the Romanian Academy organized the “Asteroid Day – Open Doors Day” event in the scientific and educational park of the Astronomical Observatory in Bucharest. On this occasion, approximately 200 visitors explored the scientific heritage spaces of the Institute and discovered rare instruments, themed exhibitions, and interactive educational activities.

In the Meridian Hall, the public was guided through scientific equipment of historical value, such as the “National Treasure” Gautier-Prin telescope and the two fundamental pendulum clocks – Le Roy and Riefler. The latter operated using a high-precision pendular system with electromagnetic impulse and rigid suspension, originally mounted on independent foundations to eliminate ground vibrations – essential conditions for accurate astronomical time measurements. Another highlight was the AFU-75 camera – a Soviet-era astrophotographic device designed for satellite tracking, mounted on an equatorial platform with a multi-axis tracking system and a specialized focal plane film exposure mechanism. It was successfully used by Romanian astronomers for mapping and orbital determination, and it was calibrated using rigorous optical methods. The exhibition of mechanical calculating machines – Rheinmetall, Mercedes, and Odhner – attracted those passionate about the history of technology. These devices, based on gear wheels and cams, allowed Romanian astronomers to perform complex operations such as reducing stellar coordinates, calculating ephemerides, and processing photo-astronomical observations before the advent of electronic computers.

Visitors also admired a collection of meteorite fragments, both metallic and chondritic – relics of the primordial nebula from which the Solar System formed. The chondritic fragments, rich in silicates, are among the oldest known rocks in the solar system.

In the Equatorial Dome, visitors discovered the Prin-Merz astrograph – also classified as a National Treasure of Romania – which was used for both photographic and visual observations, and they attended PowerPoint-supported presentations dedicated to it.

In the Main Hall and Planetarium Room, visitors were welcomed by a wonderful exhibition of paintings by students from the "Nicolae Tonitza" Fine Arts High School in Bucharest, as well as by interactive activities coordinated by the astronomy club “Space Club” of the Military Astronomical and Radiocommunications Agency (MAPN), alongside the Environmental Department of the Bucharest City Hall and the Red Cross. Workshops for children, demonstrations, and discussions on astronomy, ecology, and health were held throughout the day.

In the Planetarium Room, the event program included a series of presentations highlighting the role of astronomy in understanding the physics of the Sun, the seasons, orientation using stars and constellations, as well as an introduction to the exploration of the Moon, focusing on lunar relief, phases, and eclipses.

In the northern section of the Observatory’s scientific park, throughout the event, visitors observed the Sun safely through a professional solar-filtered astronomical instrument.

Published on: Jul 06, 2025