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Modern Solar Research Astronomers find better conditions to observe the sun than in at facilities in high altitude mountains with a high amount of cloudless days. Together with other German solar research institutes and the Spanish Instituto de Astrofisica de Canarias (IAC), the AIP does research at the observatory on Tenerife.

The Vacuum Tower Telescope (VTT) and, as of May 2012, the GREGOR – the most modern solar telescope in Europe with an aperture of 1.5 meters - stand almost 2,400 meters high. The Sun in Figures Mass: 1.989 x 1030 kg (ca. 330K x Earth‘s mass) GREGOR’s large light gathering area allows for Diameter: 1,390,000 km (ca. 104 x Earth‘s diameter) observation of the sun of unequalled quality and 26 resolution. Atmospheric disturbance is compen- Luminosity: 3.844 x 10 W sated for through a new system of adaptive lenses. Age: 4.6 billion years With these observations, physical processes on Magnetic Field: max. 0.45 Tesla (7,500 x that of Earth) the sun can be studied on a spatial scale of up to Distance to Earth: 149.6 million km (8.3 light minutes) 70 kilometres. Temperature Surface: 5,800 Kelvin (ca. 5,500 °C) Core: 15.7 million Kelvin

Rotation Period At the Equator: 25.6 days At the Pole: 36 days

Contact Leibniz Institute for Astrophysics Potsdam (AIP) www.aip.de, [email protected] For public tours of the Telegrafenberg and – only in winter – Einstein Tower, please contact the Urania Association “Wilhelm Foerster”. Einstein Tower The GREGOR Solar Telescope on Tenerife. www.urania-potsdam.de Functional Building The Telescope In the middle of the grandiose expressionistic building, and Architectural a vertical telescope is permanently mounted on a baseplate. The telescope’s lens has a 60-centimeter Masterpiece diameter and 14-meter focal distance.

The Einstein Tower was planned and built by between 1919 and 1924. The architect adhered to the specifications of astronomer Erwin Finlay-Freundlich, designer of the scientific tower telescope. Einstein Tower was the most significant solar telescope in Europe up until the Second World War. The observation programme was comprised of experiments in solar physics as well as atomic and plasma physics. At night. The planned proof of Einstein’s predicted gravitational of solar spectral lines, however, was not Coelostat in the dome. spectral polarimetric measurements of sun spot accomplishable. groups. Spectrum and polarisation analysis allow Einstein Tower underwent extensive renovations Within the dome is a coelostat that uses two mirrors to conclusions to be made regarding the magnetic field in 1999, which were in large part funded by the direct the sunlight in the telescope. The light is guided and velocity field on the surface of the sun. Wüstenrot Foundation. Einstein Tower, now a part horizontally into the laboratory via an additional As the “resident instrument” of the Leibniz Institute of the Leibniz Institute for Astrophysics Potsdam, is rotatable mirror in the basement. The centrepiece is a for Astrophysics Potsdam (AIP), the Einstein Tower attributed to the era of Expressionism in architectural 14-meter-long spectrograph room that extends to the plays an important role to this day in the preparation history. end of the bank on the south side of the tower. In this and testing of new experiments and equipment temperature-stabilised room, sunlight is separated bound for use in large modern solar telescopes. into its spectral components and analysed. Proven methods of measuring sunlight are also transferable for measuring starlight. The immediate availability of this equipment is essential for these Science at Einstein Tower measurements as well as for the training of students. The tower telescope and binocular spectrographs The AIP continues the tradition of solar research used at Einstein Tower comprise a very effective solar both in and out of Potsdam to this day. research facility to this day. The most modern optical and mechanical apparatuses in a temperature stable laboratory allow for a spectral resolution of 1:1 million and highly sensitive polarization measurements of light. The main focus of the observations is Cross-section of Einstein Tower.