My first Magazine Sky & Telescope - 03.2019

another of Herschel’s many amazing observations based solely on the visual appearance of objects in his telescopes. James Mullaney Rehoboth Beach, Delaware Scaling the Void Great article on the Local Void (S&T: Oct. 2018, p. 12)! But like all huge structures, I had difﬁ culty visualizing it, so I tried scaling. Make 1 million light-years equal 1 meter (3 feet): The Milky Way is now a disk 9 cm (3.6 inches) wide. If you’re facing the Local Void with the Milky Way in front of you, Andromeda is off to your left 2.5 meters, a disk about 20 cm wide. M33, the Triangulum Galaxy, is a 2.5-cm disk to the left and below Andromeda, about 1 meter from it. Have a friend hold the Milky Way while you go 1.5 meters past it and you pass Barnard’s Galaxy (NGC 6822). Go another 2 meters and you pass the Sagittarius Dwarf Irregular Galaxy. Now for another 250 meters you walk through completely empty space. Look back when you reach the end of the Local Void, and the Milky Way and Andromeda are very small and faint. I’ve written an article using the solar system model in front of Grifﬁ th Observatory to show how far away the Oort Cloud and Alpha Centauri are. When you use my scale for the Local Void on this model, you come to realize just how large the void really is. Dave Nakamoto Azusa, California Moonset Moment Eli Maor’s justiﬁ ably reverent Focal Point (S&T: Dec. 2018, p. 84) overlooks the profound inspiration that human- kind’s ﬁ rst crewed visit to another world gave to my baby boomer generation. I vividly remember that Christmas 1969 1994 Daniel Costanzo Locust Grove, Virginia FOR THE RECORD • In “New Year’s Eve Celestial Celebration” (S&T: Dec. 2018, p. 22), the actual distance for Altair is 17 light-years. • In Gallery (S&T: Jan. 2019, p. 76), Nebula CTB-1 should be 36 arcminutes in diameter. SUBMISSIONS: Write to Sky & Telescope, 90 Sherman St., Cambridge, MA 02140-3264, U.S.A. or email: letters@ skyandtelescope.com. Please limit your comments to 250 words; letters may be edited for brevity and clarity. 75, 50 & 25 YEARS AGO by Roger W. Sinnott 1944 Eve in 1968 when Apollo 8’s crew gave the ﬁ rst-ever “Live from the Moon” television broadcast. While the Moon’s magniﬁ cently desolate features scrolled across my family’s black-and-white TV screen and the astronauts read from the Book of Genesis, I looked out my win- dow and saw the actual Moon setting outside in the wintry night. So, besides the Apollo 8 crew’s iconic Earthrise moment, my Moonset moment brought a little boy a profound awareness of our place in the universe. º March 1944 Titan’s Air “Titan [is] the princi- pal satellite of Saturn. . . . Late in January, Dr. Gerard P. Kuiper . . . reported from the McDonald Observatory in Texas that he had obtained spectra of Titan in red and infrared light. These spectra reveal an atmosphere rich in hydro- gen. It is much like the atmosphere of Saturn itself, containing methane (marsh gas) and possibly ammonia. . . . Life, as we know it, is as much out of the question on Titan as on Saturn.” We now know Titan’s atmo- sphere is largely nitrogen, but it does have some methane. Dorrit Hofﬂeit’s ﬁnal remark also needs a different emphasis. Astrobiologists think Titan could well harbor some exotic form of life. º March 1969 Missing Mass “A major discrep- ancy arises when astronomers try to determine the mass of a cluster of galaxies. Such a cluster is equivalent to more than 100 million million suns. The system’s mass can be calculated from the motions of the galaxies in it, but when the individual masses of the member galaxies are added up, the sum is more than 10 times smaller! . . . “This had been discovered for the giant cluster in Coma Berenices by Fritz Zwicky in 1933. [And at a 1961 meeting of astronomers in] Santa Barbara, cluster after cluster — both large and small — was added to the list.” The curiosities cited by Herbert J. Rood (Van Vleck Observatory), plus other lines of evidence, have grown into the major cosmological problem of “dark matter.” º March 1994 Big Bang, or . . . ? “The gauntlet thrown, Sky & Telescope’s chal- lenge to rename the Big Bang immediately struck a chord among the public. [In the end we] processed 13,099 entries from persons in 41 countries. . . . “Creation was submitted 124 times, followed closely by Cosmo- genesis. . . . Damaru (the Hindu drum of creation) was suggested. . . . Those opting for modern-day English often resorted to terms that evoked a certain awe or puzzlement. A 90-year-old entrant submitted Out of the Misty Mystery. . . . But some contestants, and not just the professional astronomers, had a good grasp of the standard model. They pictured the universe as an expanding entity with such titles as Super Seed, . . . Hawking’s Hunch, Planck Point, and Hubble Bubble. . . . And then there was Bertha D. Universe. . . . “A small minority thought they might influence judges Timothy Ferris, Hugh Downs, and Carl Sagan [with a name like] BS (Before Sagan). . . .” Sagan had predicted that no one would be clever enough to outdo Fred Hoyle’s ﬂawed and sarcastic term, Big Bang. And the judges’ ﬁnal verdict turned out to be: Leave it alone! sk yandtele scope.com • M A RCH 2 019 7

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