The Double Stars (1835) - J. J. Littrow - English edition
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The Double Stars - Presented in a Popular Style
J. J. Littrow
(1835)
New English translation by Richard E. Schmidt
The pride of the U. S. Naval Observatory in Washington, D. C. is the marvelous 26-inch aperture Alvan Clark refractor. Its long focal length has made it an indispensable instrument for observing double stars. Updated with new computer control and a speckle interferometer, it is in use every clear night adding observations to the Washington Double Star Catalog, the world's principal database of astrometric double and multiple star information. This database holds over 2.2 million observations of over 157,000 star systems.
Today, measuring the orbits of double and multiple star systems has great value in the study of stellar evolution. These stars provide the only method of determining stellar masses, the most fundamental property of stars. The U. S. Navy relies upon the most precise positions of the navigational stars used by star trackers, where correction to the photometric center of unresolved binaries becomes important, as the vast majority of the brighter stars are double stars and not single points of light.
J. J. Littrow’s universe of 1835 was vastly unexplored, especially regarding the “fixed stars” and objects beyond our solar system. Only a few thousand double stars had been discovered to date. As Littrow writes in Die Dopplesterne, “To admit it right at the outset, we know absolutely nothing about the absolute size or the distance of any fixed star without exception” . . . “We are unable to determine the distance to even a single fixed star with any degree of accuracy—that is to say, to within many millions of miles” . . . “It is impossible to accurately measure the 4th, 9th, or 16th part of the luminous intensity of a star. . .”
Nonetheless, in the first half of the 19th century there was a very great interest in double stars, spurred on to a great extent by the astronomer John W. F. Herschel who in March 1826 read before the Royal Society in London his paper “On the Parallax of the Fixed Stars.” It is very easy to understand what is meant by parallax. Put your two index fingers in front of your eyes, one hand behind the other. Move your head from left to right and see the more distant finger follow that movement behind the nearer finger. Now imagine the fingers are two distant bodies in space, and your head is the Earth itself, moving around the Sun over a baseline of 185 million miles. Herschel proposed observing double stars at intervals of 6 months to look for the parallax effect.
John Herschel and his father William, along with F. G. W. Struve at Dorpat Observatory pioneered the sky surveys that catalogued the known double and triple star systems. As Littrow explains in Die Doppelsterne, their study was fundamental to our understanding of cosmology. In his Philosophiae Naturalis Principia Mathematics of 1687, Isaac Newton described his law of universal gravitation, postulating that every particle in the Universe attracts every other particle with a force that is proportional to the product of their two masses, and inversely proportional to the square of their mutual distances. Newton’s law seemed to fit very nicely the observed orbits of the planets around our Sun, but was it truly a universal law? Did it hold in the far reaches of space, or did other regions follow different laws? The double stars were themselves orbiting bodies. Would their observations validate the universality of Newton’s law? Littrow takes up this question in The Double Stars.
With a descriptive list of double and triple stars suitable for small telescopes, and a new introduction by Richard E. Schmidt, this first-ever English language translation brings Littrow's rare book to a new generation of readers.
J. J. Littrow
(1835)
New English translation by Richard E. Schmidt
The pride of the U. S. Naval Observatory in Washington, D. C. is the marvelous 26-inch aperture Alvan Clark refractor. Its long focal length has made it an indispensable instrument for observing double stars. Updated with new computer control and a speckle interferometer, it is in use every clear night adding observations to the Washington Double Star Catalog, the world's principal database of astrometric double and multiple star information. This database holds over 2.2 million observations of over 157,000 star systems.
Today, measuring the orbits of double and multiple star systems has great value in the study of stellar evolution. These stars provide the only method of determining stellar masses, the most fundamental property of stars. The U. S. Navy relies upon the most precise positions of the navigational stars used by star trackers, where correction to the photometric center of unresolved binaries becomes important, as the vast majority of the brighter stars are double stars and not single points of light.
J. J. Littrow’s universe of 1835 was vastly unexplored, especially regarding the “fixed stars” and objects beyond our solar system. Only a few thousand double stars had been discovered to date. As Littrow writes in Die Dopplesterne, “To admit it right at the outset, we know absolutely nothing about the absolute size or the distance of any fixed star without exception” . . . “We are unable to determine the distance to even a single fixed star with any degree of accuracy—that is to say, to within many millions of miles” . . . “It is impossible to accurately measure the 4th, 9th, or 16th part of the luminous intensity of a star. . .”
Nonetheless, in the first half of the 19th century there was a very great interest in double stars, spurred on to a great extent by the astronomer John W. F. Herschel who in March 1826 read before the Royal Society in London his paper “On the Parallax of the Fixed Stars.” It is very easy to understand what is meant by parallax. Put your two index fingers in front of your eyes, one hand behind the other. Move your head from left to right and see the more distant finger follow that movement behind the nearer finger. Now imagine the fingers are two distant bodies in space, and your head is the Earth itself, moving around the Sun over a baseline of 185 million miles. Herschel proposed observing double stars at intervals of 6 months to look for the parallax effect.
John Herschel and his father William, along with F. G. W. Struve at Dorpat Observatory pioneered the sky surveys that catalogued the known double and triple star systems. As Littrow explains in Die Doppelsterne, their study was fundamental to our understanding of cosmology. In his Philosophiae Naturalis Principia Mathematics of 1687, Isaac Newton described his law of universal gravitation, postulating that every particle in the Universe attracts every other particle with a force that is proportional to the product of their two masses, and inversely proportional to the square of their mutual distances. Newton’s law seemed to fit very nicely the observed orbits of the planets around our Sun, but was it truly a universal law? Did it hold in the far reaches of space, or did other regions follow different laws? The double stars were themselves orbiting bodies. Would their observations validate the universality of Newton’s law? Littrow takes up this question in The Double Stars.
With a descriptive list of double and triple stars suitable for small telescopes, and a new introduction by Richard E. Schmidt, this first-ever English language translation brings Littrow's rare book to a new generation of readers.
