Wednesday, July 24, 2019

Binocular Highlights (Book Review)

Binoculars are easy to carry. The images in the very wide field of view are correct vertically and horizontally. Without a tripod (or monopod), you will steady them as best you can, seated with your elbows on your knees. And, even so, some of your targets will be overhead, so those solutions remain inoperative. Nonetheless, the advantages outweigh the difficulties. 

(Submitted to Sidereal Times of the Austin Astronomical Society.) As with telescopes, bigger is better, up to a limit of convenience. The author warns that the impressive views of larger instruments require a heavy-duty mount and tripod. That said, even a small set will reveal celestial sights unavailable to the naked eye – which is the point of viewing with any instrument. Binoculars deliver broad and wide vistas of deep sky clusters and nebulae. 
Binocular Highlights:
109 Celestial Sights for Binocular Users,
by Gary Seronik,
Sky & Telescope, 2017,
112 pages +4 fold-out maps, $24.99. 
Seronik explains the optics. He also clarifies the parameters of the instruments. A pair of 10x35 are 10 power with a 35-mm objective lens. On the frame, you will likely find another measure. My 12x45 Bushnell (purchased from the close-out aisle at Walmart for $39.95) say 225 FOV at 1000 yards. However, my little Vivitars ($29.95 retail), which I measured as 30mm, keep all of their secrets. Seronik does discuss the latest computer-driven image-stabilizing options, but only briefly. His heart is with “The Allure of Cheap Binoculars.” The reason why is that the optics are usually a given. It is a known technology. Better, more expensive products have sturdier mechanics: they take travel well and stay tight over time. 

If you have the first edition, and have been active with it you probably do not need the new printing. As far as I can tell, comparing page by page, the only differences are the ten new objects. If you have been out often with your “binos” since 2010, then you may well have penciled them in on your own. 

Among the new targets is Albireo, which should be on everyone’s list. Others, such as NGC 2243 and NGC 2345 in Monoceros and M56 in Cygnus are going to be a challenge even with 50 mm objectives, except under ideal conditions. Also among the additions are the open clusters Cr 132 and Cr 140 in Canis Major. They may stand out for you because of their relative brightness, +3.6, but it may be hard to resolve them better than points of light. Even so, the thrill of the hunt is one of the strongest motivators that we astronomers enjoy. 


Saturday, July 13, 2019


On Friday night, July 12, Nobel laureate Steven Weinberg was the guest speaker at the monthly Austin Astronomy Club meeting. His topic was gravitational waves. 

(The grammar can be important. A “gravity wave” is actually a weather event here on Earth. Waves on the ocean are gravity waves. But we call gravitation waves “gravity waves” just as we sometimes are careless with “speed” and “velocity”.)

Dr. Steven Weinberg
(UT Austin)
Dr. Weinberg said that the LIGO (Laser Interferometer Gravitational-Wave Observatory) apparatus was an advance in the technology of perception as significant as Galileo’s use of the telescope. According to the LIGO website, gravitation waves are as different from electro-magnetic radiation (“light waves “) as light is from sound. 

Dr. Weinberg credited A. A. Michelson with the development of the kind of interferometer used for these investigations. (The Michelson-Morely Experiment of 1887 failed to find the "ether" in which light travels.) Reading websites before the lecture, it was apparent to me that these arrangements are extensions of the Michelson-Morley experiment. Long paths of light set at right angles and placed far apart (Hanford, Washington; Livingston, Louisiana; and Pisa, Tuscany), are superimposed so that the smallest variation is revealed by an interference pattern. 

Entropy is real. The Moon will collide with the Earth – eventually. When neutron stars and black holes orbit each other, the losses of energy are (what else?) astronomically immense, and collisions and collapses are recorded as “chirps” of about a half a second.
It is also true that as they rotate on their individual axes, massive bodies produce gravitation waves.* Any acceleration does, even when you turn the corner on your bike or in your car. But gravity is extremely weak. At shoulder height, place a golf ball next to a bowling ball and let go of the golf ball. They don’t stick. Now, try it with magnets. I was once told that machine shop gauge blocks are finished so fine that if they touch they cannot be separated because the molecular forces are insuperable: the two blocks become one. Gravity is not like that. 

So, even though gravitation waves were argued by Newton, Leibniz, Kant, and Berkeley, it was 300 years before they were first detected on 14 September 2015. Dr. Weinberg also praised the intellectual honesty of the previous attempts by Joseph Weber and others which meticulously ruled out false positives until nothing was left.

*The gravitation waves produced by a massive superdense rotating body are caused by minor variations within or on the surface of the body. A vibrating perfect sphere produces no gravitation waves.