HIGHLIGHTS IN ESTONIAN ASTRONOMY

Solar System

• 1932 - Ernst Öpik presents an idea about cloud of comets at a distance of 50 000 - 100 000 au, called now as Öpik-Oort cloud.
• 1937 - Ernst Öpik presents the physical theory of meteors.

  Stars

• 1835 - 1836 Wilhelm Struve measures the first time in the world the distance to the star (Vega) using the Big Fraunhofer Refractor ( annual parallax and distance by Struve 0.125" 26.1 ly ; at present 0.123" and 26.5 ly).
• 1885 - Ernst Hartwig discovers a supernovae in the Andromeeda nebulae , the first historical supernovae outside the Milky Way (brightness in the maximum 6 magnitudes).
• 1922 - Ernst Öpik presents the idea of nuclear fusion energy in the center of of stars
• 1937 - Ernst Öpik presents the theory of stellar structure, and shows that the stellar evolution goes from the main sequence to red giants
• 1950 - Aksel Kipper presents the theory of double photon transitions in the nebulae , explaining forbidden lines in their spectra
• 1978 - Arved Sapar participates in the observations by UV satellite IUE resulting in a great number of stellar and interstaller matter spectra

  Stellar systems and galaxies

• 1922 - Ernst Öpik determines the first time the distance to the galaxy ((Andromeda) using dynamical method developed by himself, and establishes extragalactic distance scale (the distance by Öpik was 450 kpc, contemporary value - 770 kpc).
• 1953 - Grigori Kusmin presents the theory of the third integral of the stellar systems; this paper along with following ones belong to the classics of stellar dynamics (Kusmin's disc, theory of spherical and tri-axial stellar systems)
• 1974 - Jaan Einasto, Ants Kaasik and Enn Saar applying movements of satellite galaxies shows that besides the baryonic matter (stars,gas,dust) galaxies contain extanded haloes of dark matter
• 1977 - Jaan Einasto along with coauthors presents (at IAU Symp. 79 in Tallinn, Estonia) the discovery of the cell structure of the Universe using spatial distribution of galaxies and of systems of galaxies
• 1994-2001 Jaan Pelt in a series of papers demonstrates that the first discovered gravitational lens double quasar QSO 0957+561 A,B has signal delay between its components about 417 days, using time series analysis software developed by himself, which enabled to establish independantly the value of Hubble parametre (H _o = 68 km/s/Mpc).

  Observatories and telescopes

• 1810 - Tartu Observatory (now Tartu Old Observatory) was opened where Wilhelm Struve started his scientific carrier in 1814. A long-term tradition of professional astronomy was founded in Estonia
• 1824 - mounting of the Big Fraunhofer Refractor, the largest and the most modern lens telescope in the world , in Tartu Observatory (9" lens in diametre, clock mechanism and acromatic optics)
• 1930 - Estonian optician and astronomer Bernhard Schmidt presents his abberation free wide view mirror telescope - Schmidt camera, (in Bergedorf Observatory, Hamburg). Schmidt camera includes a spherical mirror and a correction plate which enable its high quality
• 1964 - opening of the new obseratory (now Tartu Observatory) at village Tõravere (20 km from Tartu)
• 1974 - mounting of the 1.5 m mirror telescope at Tõravere, largest telescope in Estonia
• 2005 - Struve Geodetic Arc and Tartu Old Observatory included into the UNESCO World Heritage List

  Publications and conferences

• 1817 - W. Struve started "The Publications of the Tartu Observatory" which appeared up to 1990, and was then the oldest periodical publication in astronomy of the world
• 1924 - an almanac for Estonian professional and amatuer astronomers "Tähetorni Kalender" started to appear (published up to now)
• 1977 - IAU Symposium 79 "Large Scale Structure of the Universe" was held in Estonia (Tallinn)
• 2002 - Enn Saar along with Vicent Martinez (Valencia, Spain) published an extended handbook in astronomy "Statistics of the Galaxy Distribution"