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75, 50 & 25 YEARS AGO.

February 1943

Wartime Astronomy "The American Astronomical Society's Committee on the Continued Distribution of Astronomical Literature has just received a packet of various German astronomical journals and publications from seven German observatories, issued in 1939-41 and the first half of 1942.... Solar research, studies of Cepheid variables and of the zodiacal light are especially prominent....

"Numerous issues give abstracts of astronomical papers published in Italy; one, a list of those published in Japan....

"These publications are entirely devoted to astronomy. Their only reference to the war is in the personnel notes in the directors' reports. They serve no propaganda purposes.... May our common understanding in this science eventually be extended to life in general."

This report by astronomer Dorrit Hoffleit was made into an editorial.

February 1968

Hide and Seek "Any binary star system will be an eclipsing variable if its orbit plane is nearly enough edgewise to us.... So far, no trustworthy case is known of a visual binary system having shown an eclipse.

"Paul Couteau [at Nice Observatory] calls attention ... to the remote chance that this phenomenon will occur in 1968. The visual binary OI 536 [near Rho Pegasi] has a period of 27 years and an orbital inclination of approximately 90 degrees, according to G. Van Biesbroeck....

"Dr. Couteau calculates that if eclipses occur, one will happen around mid-April, 1968, with a maximum duration of 5.8 days...."

No one reported seeing that eclipse. A more famous case of missed but likely eclipses is Alpha Comae Berenices, a visual binary with a 26-year period. A secondary eclipse might occur about January 11, 2026, and a likely primary eclipse near September 24, 2040.

February 1993

Mirror-Image Galaxy "A remarkable example of gravitational lensing in a distant cluster of galaxies is giving astronomers second thoughts about the nature of dark matter.

"The Hubble Space Telescope made the discovery while peering into the heart of AC 114, a galaxy cluster some 4 billion light-years away. Two 6-hour exposures with Hubble's Wide Field and Planetary Camera revealed a pair of faint objects that look almost exactly like mirror images of each other. At a press conference at NASA headquarters on October 8th, "Richard Ellis (Durham University, England) identified them as gravitational mirages of a more distant galaxy produced by the lensing action of the intervening cluster's mass....

"Ellis and his colleagues have computed the amount and distribution of mass needed to produce the mirages. Their model requires up to 50 times more matter than is visible in the cluster's galaxies."

Caption: 1943

Caption: 1968

Caption: 1993

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Title Annotation:From Our Readers
Author:Sinnott, Roger W.
Publication:Sky & Telescope
Date:Jan 10, 2018
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