TIKHOV, GAVRIIL ADRIANOVICH

(b. Smolevidhi, near Minsk, Russia, 1 May 1875: d AlmaAta, Kazakhstan S.S.R., 25 January 1960)

astrophysics, astrobotany.

Tikhov was the son of a railway stationmaster. In 1893 he graduated from the Gymnasium in Simferpol with a gold medal and entered the mathematical section of Moscow University. He graduated in 1897 with a first-degree diploma. From 1898 to 1900 he studied in Paris at the Sorbonne and worked as a probationer in Jules Janssen’s astrophysics observatory in Meudon. At Janssen’s suggestion Tikhov, on 15 November 1899, observed a meteor shower from a balloon. Twice he ascended Mont Blanc to work at Janssen’s mountain observatory.

After returning to Russia, Tikhov taught mathematics at a Moscow Gymnasium and then at the Ekaterinoslav Higher Mining School. He also studied meteors and variable stars. In 1906 he was named extra-staff adjunct-astronomer at the Pulkovo observatory. using the so-called Bredikhin short-focus astrograph, Tikhov began work on photographic astrocolorimetry, using two parts of the spectrum, separated by special coilor flters,. He sensitized films to the necessary portions of the spectrum, and prepared gelatin filters colored with various dyes. In 1913 he successfully defended his dissertation for the degree of master of astronomy and geodesy.

From 1914 to 1917 at the Central Aeronautical navigation Station of the Pilot Observer Military School, Tikhov worked on ways of improving visibility from airplanes and developed light filters and special photographic film for aerial photography. His first monograph on aerial photography (1917) dealt with methods for improving visual and photographic air reconnaissance. It was widely used by pilots of the Allied armies.

After the war Tikhov returned to Pulkovo, and from 1919 to 1931 he also lectured on astrophysics at the University of Leningrad. From 1919 to 1941 he directed the astrophysics laboratory of the P.F. Lesgaft Scientific Institute.

In 1927 Tikhov was elected corresponding member of the Academy of Sciences of the U.S.S.R., and in 1935 he received the drgree of doctor of physical and mathematical sciences. he observed the total solar eclipse of 21 September 1941 in Central Asia and subsequently worked at a branch of the U.S.S.R. Adademy of Sciences. When the Kazakh S.S.R. Academy of Sciences was organized in 1946, he became an active member. In 1917 Tikhov became head of the section of astrobotany, which he had orgaonized. In 1947 he became professor of astronomy. he was a member of the International Astronomical Union, the Americal Astronomical Society, and a number of Soviet scientific societies.

By means of colorimetry Tikhov studied the dispersion of light in interstellar space, that is, the rate of diffusion of light at various wavelengths. In this study he chose Algol variable stars, on which he detected a delay in the moment of eclipse in the shorter waves as compared to the longer waves. This phenomenon is now known as the Tikhov-Nordmann effect. (Charles Nordmann discovered this effect some time later.) The Soviet astrophysicist E. R. Mustel subsequently explained it in terms of the distortion of the form of the components and the presence of tidal waves of reduced temperature.

Tikhov later developed th method of the “longitudinal spectrograph,” in which the optical imperfections of a poorly achromatized objective lens were used for quickly and conveniently estimating the color of stars; the technique led to the publication of extensive catalogs of star colors.

An extended series of works related to observation of the total solar eclipses of 1927, 1936, and 1941 resulted in the establishment of two structural peculiarities of the solar corona–the “globular,” or “dispersed,” corona and the “radiant” corona that penetrates the streamers.

Tikhov also made photographic observations of mars using the thirty-inch refractor with light filters at the Pulkovo observatory. From this research later came the new fields of astrobotany and astrobilogy. Tikhov conceived the idea of comparing the spectrophotometric properties of natural formations on nthe earth (mountains, soils, sands, ice, snow, and plant life) with corresponding properties of various formations on Mars. Specialized investigations of the reflecting abilities of vegetation growing under severe conditions and at high altitudes showed the great degree of adaptability of life and suggested the possible existence of vegetation on Mars. Tikhov himself participated in fifteen expeditions to various mountain regions and the Arctic in support of these ideas.

Tikhov’s work on atmospheric optics was closely related to this research. In 1912 he invented an instrument for registering astral scintillation and elaborated a method for measuring the angular diameter of stars on the basis of their scintillation. He later studied the “green flash” that appears at sunset and discovered the anomalous dispersion of light in the earth’s atmosphere. He investigated ashen light of the moon, in an attempt to determine how the light of the earth as a planet would be seen from outer space. To study atmospheric optics by daylight, in a clear sky, Tikhov designed an original cyanometer and a one-dimensional colorimeter with a dark blue wedge.

BIBLIOGRAPHY

I. Original Works. Tikhov’s basic works (from his 165 writings) were published as Osnovnye trudy, 5 vols. (Alma-Ata, 1954-1960). His autobiography is Shestdesyat let u teleskopa ("Sixty Years at the Telescope"; Moscwo, 1959). His principal works in astrobotany and astrophysics (1912-1957) have appeared in English trans., 2 vols. (New York, 1960).

II. Secondary Literature. On Tikhov’s life and work, see the bibliography of his 165 published writings in Izvestiya Akademii nauk Kazadhskoi SSR, no. 90, “G. A. Tikhov,” in Izvestiya Glavnoi astronomicheskoi observatorii v Pulkove, 22 , pt. 2 (1961), 2-5; M. A. Milkhiker and M. A. Daskal,"Gavriil Adrianovich Tikhov,” in Byulleten Vsesoyuznogo astronomo-geodesicheskogo obshchestva, no. 28 (1960), 56-59; V. V. Sharonov, “Gavriil Adrianovich Tikhov,” in Priroda (1950), no. 8, 85-88; and N. M. Shtaude, “Osnovnye cherty nauchnogo tvorchestva G. A. Tikhova po lichnym vpechatleniam Za 40 let” ("The Basic Features of G. A. Tikhov’s Scientific Work From Personal Impressions Over Forty Years"), in Izvestiya Akademii nauk Kazadhskoi SSR, no. 90, Ser. astrobot., nos, 1-2 (1950), 19-24.

P. G. Kulikovsky