Opik Asserts Stellar Universe Relatively Young--Cannon Discusses Photographic Collection at New Wing Dedication

Dedication of the new Astrophotographic Building yesterday was marked particularly by the talks of Ernst J. Opik of Tartu University, visiting lecturer in Astrophysics, and Dr. Annie J. Cannon, curator of Astronomical Photographs at Harvard. Professor Opik discussed meteorites in relation to the age of the universe, while Dr. Cannon described the growth of Harvard's collection of astronomical photographs.

Opik Discusses Age of Universe

The age of groups of meteorites recently studied appears to be below 3000 million years, which suggests a low age also for the stellar universe. Professor Paneth of Konigsberg has determined the age of a number of meteorites from their relative content of helium and radium; for 24 different iron meteorites he found values ranging from 100 to 2900 million years; for the Pultusk stone meteorites, the fall of which in 1868 has been well observed, he gives a preliminary value of 500 million years, which is probably a minimum value because of possible loss of helium in space and in our museums for over 60 years. The Pultusk meteorite was certainly of interstellar origin, and judging from preliminary results of the Arizona meteor expedition, we may expect that at least several of the iron meteorites investigated by Paneth also do not belong to the solar system.

Star Masses About the Same

Statistics of the distribution of distances and relative magnitudes in double stars indicate that since their origin the masses of the stars could not decrease appreciably, and that the drop in luminosity of an average star of the dwarf branch cannot exceed half a magnitude since its origin, instead of the expected six magnitudes or more, and the probable value of the drop in luminosity is zero.

Universe Relatively Young

The conclusion is that stars of different spectral classes cannot have evolved one from another, but must have been created simultaneously, and that their age is too short for any appreciable evolution having taken place. Finally, the observed recession of spiral nebulae, reflecting the phenomenon of the expanding universe, indicates a possible age of the extragalactic universe of a few thousand million years only. From all these facts we infer that probably the age of our universe does not differ very much from the age of the solar system, and that not very much more than 3000 million years have elapsed since the spiral nebulae, the stars, and the star-dust (the meteors) were born out of the original parent system, which we call chaos because we do not know much about it.

Cannon Discusses Photo Collection

The history of astronomical photography at the Harvard Observatory, began Doctor Cannon dates from 1850, when the first photograph of a star ever taken was made here with the 15-inch Telescope. The collection numbers about 400,000 glass negatives, of sizes from 4 by 5 to 14 by 17 inches.

The earliest plates, 1850 to 1852, were daguerreotypes taken under the direction of William C. Bond, the original Director of the Observatory. The process was so slow that only the brightest stars would "take", and no impression could be made of the North Star, no matter how long the exposure.

The introduction of "wet" collodion plates brought new hope, and by their use in 1857 George P. Bond, the son and successor of William Bond, succeeded in photographing stars of the sixth magnitude, which includes all visible to the naked eye. About one hundred plates of this period are used in the Harvard collection in good condition.

The Harvard collection forms a continuous series from 1885 when dry plates were available. At that time Edward C. Pickering, the fourth Director, started with great zeal and enthusiasm on the large task of photographing the whole sky.

Photographic Telescopes

With the help of Mrs. Henry Draper of New York City, who established the Henry Draper Memorial, and of the Bache fund for the erection of an Observatory at a high altitude, four photographic telescopes were installed between 1885 and 1890, two in Cambridge and two in Peru. Up to the present time, these four telescopes have taken 142,000 plates. The results of a study of these plates include the discovery of the first spectroscopic binary; of one thousand variable stars in globular clusters and elsewhere; of ten novae; a spectral classification of 225,000 stars, and an international system of stellar magnitudes.

Bruce Gift

In 1893, by the generous gift of $50,000 from Miss Catherine Bruce of New York City, a 24-inch Doublet was ordered by Professor Pickering from Alvan Clarke and Sons, and was sent to the southern station at Arequipa, Peru, elevation 8000 feet. Although this unprecedented size for a doublet was strongly criticized in those days, the glass has been effective and is responsible for 16,000 negatives in the Harvard collection, most of them 14 by 17 inches in size.

The revelations from the Bruce plates include the faint ninth satellite of Saturn, Phoebe, numerous characteristics of the Magellanic Clouds, the discovery in them of 2000 variables and the "Period Luminosity" relation (one of the most efficient measuring tapes for the scale of the universe). At least 30,000 spiral nebulse have also been located by means of the Bruce Telescope.