From the Effelsberg Radio Telescope to the Institute for Space Systems (IRS)
The Milky Way Trail Makes a Stop at the University of Stuttgart
On July 16, 2026, an external trail panel for the Milky Way Trail at the Effelsberg Radio Telescope will be installed at the Institute for Space Systems (IRS) at the University of Stuttgart. The panel, which will be visible from outside the building and features information about the Triangulum Galaxy (M33), will mark the Stuttgart institute as another branch of the trail at a scale-accurate distance.
The Milky Way Trail is one of three astronomical hiking trails of different scaling at the Effelsberg Radio Telescope. Together, they allow visitors to experience the full range of cosmic distances, from the planets of our solar system to distant galaxies billions of light-years away.
The Milky Way Trail is a project of the Max Planck Institute for Radio Astronomy and the Effelsberg Radio Observatory. It was established in collaboration with the Freundeskreis Sahrbachtal e.V. as a hiking trail with a total length of four kilometers in the immediate vicinity of the Effelsberg radio telescope.
With a diameter of 100 meters, the radio telescope is the second-largest steerable radio telescope in the world. The Milky Way Trail illustrates the distances to various celestial bodies on a scale of 1:1017 (1:100 quadrillion)—which corresponds to 10,000 light-years per kilometer. On this scale, the Milky Way has a diameter of ten kilometers. The distance of 25,000 light years between Earth and the center of the Milky Way, scales to 2.5 kilometers.
In addition to the 20 main stations in the vicinity of the radio telescope in the Eifel region, there are a number of satellite stations that extend the trail. Since 2014, there has been a station dedicated to the well-known Andromeda Galaxy (Messier 31) at the House of Astronomy on Heidelberg’s Königstuhl. In 2021, the Mannheim Planetarium was added as the location for the galaxy NGC 205, a companion to the Andromeda Galaxy. As recently as July 2026, another external station on the Milky Way Trail was added: the Draco Galaxy at the Friedrich-Ebert-Gymnasium in Bonn.
Next is the Triangulum Galaxy (Messier 33), a prominent member of the Local Group of galaxies in the vicinity of the Milky Way, located at a distance of about 2.6 million light-years. On the scale of the Milky Way’s trail (1 : 1017 or 1 : 100 quadrillions), this corresponds almost exactly to the aerial distance of 260 km between the IRS in Stuttgart and the Effelsberg radio telescope. The Triangulum Galaxy is one of the three large spiral galaxies in the Local Group, alongside the Milky Way and the Andromeda Galaxy, and is visible in the sky even with small optical instruments (binoculars) under good viewing conditions. Its name is derived from the constellation Triangulum (meaning “Triangle” in English), in the direction of which it can be found in the sky. The constellation Triangulum borders the constellation Andromeda directly to the south, and in fact, the two galaxies are only about 14 degrees (or 28 full moon diameters) apart.
With the Triangulum Galaxy (M33), there are now four external stations along the Milky Way Trail. They also mark the transition from the Milky Way Trail to the third astronomical trail at the Effelsberg Radio Telescope: the Galaxy Trail, with a scale of 1 : 5 x 1022 (1 : 50 thousand billion billion). On this scale, the Andromeda system—including NGC 205 and Messier 31—is in the immediate vicinity of the Milky Way, at a distance of just 50 centimeters. The two panels, “Milky Way” and “Andromeda Galaxy,” standing just 50 cm apart, mark the beginning of the Effelsberg Galaxy Trail, which extends over a total distance of just under three kilometers to distant galaxies several billion light-years away
The transition between the Planetary Path and the Milky Way Path is marked by the brightest star in the night sky, Sirius. Sirius lies at a distance of just under nine light-years in the direction of the constellation Canis Major (the Greater Dog). On the Milky Way Path, the two stations “Sirius” and “Sun/Earth” are only 90 cm apart; on the scale of the Planetary Trail, the distance is a whopping 11,000 km. This corresponds to the distance between two radio telescopes operated by the MPIfR: the 100-meter Effelsberg Telescope and the APEX Telescope in Chile. And indeed, since 2018, the “Sirius” panel has been on display at APEX on the Chajnantor Plateau, located at an altitude of 5,100 m, as an extension of the Planetary Trail. The distance of 310 light-years to Canopus, the second-brightest star in the sky, however, already required a station at a distance equivalent to that of the Moon.
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Additional Information
The Max Planck Institute for Radio Astronomy has established a total of four topical astronomical hiking trails at the site of its 100-meter radio telescope near Bad Münstereifel-Effelsberg. Three of these trails—named the Planetary Trail, the Milky Way Trail, and the Galaxy Trail—cover the entire cosmic distance scale, from the planets of our solar system to distant galaxies several billion light-years away.
The Planetary Trail, on a scale of 1 : 7.7 billion, runs for a total length of 766 m from the visitor parking lot at the radio observatory (panel for dwarf planet Pluto) to the forecourt of the visitor pavilion, where the “Sun” panel is located. The Planetary Trail has a branch location 11,000 km away (equivalent to 8.6 light-years) at the MPIfR’s APEX telescope in the Atacama Desert in Chile, featuring the neighboring star Sirius, the brightest star in the night sky.
The Milky Way Trail, on a scale of 1 : 1017 (1 : 100 quadrillion), stretches a total of 4 km (equivalent to 40,000 light-years through our home galaxy) from the outer regions near the Sun to the galactic center. This trail leads from the Burgsahr district of the municipality of Kirchsahr in the Sahrbach Valley to a viewing plateau immediately in front of the 100-meter radio telescope itself. The Milky Way Trail has now four satellite locations—the Andromeda Galaxy M31 at the House of Astronomy in Heidelberg, the galaxy NGC 205 at the Mannheim Planetarium, the Draco Galaxy at the Friedrich-Ebert-Gymnasium in Bonn and the galaxy M33 at the Institure of Space Systems in Stuttgart—each in scaled distance to the Effelsberg Radio Telescope.
The Galaxy Trail, scaled at 1 : 5 x 1022, runs over a total length of 2.7 km (corresponding to just under 14 billion light-years) from our Milky Way to distant galaxies and finally back in time to the Big Bang or the beginning of time. It starts on a forest trail behind the radio telescope and leads to the Martinshütte in the municipality of Kirchsahr, the “barbecue hut at the end of the universe.”
To mark the 50th anniversary of the 100-meter radio telescope in 2021, another hiking trail was added: the “Time Travel Trail,” which chronicles the 50-year history of the Effelsberg Radio Telescope across a total of 20 stations. It winds around the telescope for a length of 5 km, starting right at the visitor pavilion.