Vladimir Rubtsov: The Tunguska Mystery. 318 p. Springer 2009.
Review © Norman Sperling, February 22, 2013
The explosion of a large meteor above Chelyabinsk, on the same day as asteroid 2012 DA14 buzzed Earth, has brought back the riddle of the Tunguska event.
In 1908, far to the east of the Ural Mountains, over the Podkamennaya Tunguska River in central Siberia, something - an icy, rocky asteroid or comet? - slammed into Earth's atmosphere, exploded in the air, flattened a forest, and triggered unusually bright and colorful skies over much of the world for many days.
The site is terribly remote. Communication and transportation were primitive in the terminal times of the tsarist empire. After World War I, the new Soviet regime clamped down on communications with non-Communists.
Very little news about the Tunguska explosion leaked out through the Iron Curtain. A few Soviet scientists explored, but hardly any of their data reached the West. Eyewitness reports were gathered, but we didn't see them. Important scientists declared solutions, but we only heard their answers, not their supporting data.
The absence of scientific data opened infinite possibilities for speculation. Creative minds responded by suggesting a colorful variety of explanations. Some of those caught the public imagination.
Unbeknownst to the West, much the same was happening in the Soviet Union. By selecting favorite reports, theorists put together plausible narratives which hung together only as long as all other data were ignored.
This grated on a lot of Soviet scientists. After Stalin died in 1953, Khrushchev loosened the repression. Professional and amateur scientists responded creatively by founding the Independent Tunguska Exploration Group in 1958. These days the fashionable name for this centuries-old practice is "Citizen Science".
Investigators gathered information to plug holes in previous work. We hardly ever heard their results. In this book, an ITEG stalwart describes their research, findings, and speculations.
The story is FAR more complex than I had imagined. Exploration found a great deal more information than I had ever heard of, much of it scientifically strong. Practically all of it appears to contradict some theory or other. Several fairly strong solutions have been proposed, accounting for large portions of the observations. No solution, however, has yet accounted for all the credible data.
So this book is a superb example of exploratory science, and a superb example of a scientist who understands how much he doesn’t understand.
The most frequent suggestions are comets or meteoroids or asteroids. One huge problem is that our concepts of these have changed often, and radically, over the last 100 years, so the proposal means different things to different people at different times. Recent understandings relate comets to primitive chondrite meteoroids, which are extremely similar to asteroid types C, P, D, and K. Those meteoroids are probably chips of those asteroids. If they have surface ice, they appear as "comets". The Sun can vaporize surface ice while leaving ice inside.
Yet many details, from the exact pattern of the fallen trees, to eyewitnesses describing one object approaching from the south while a second one came from the east, to chemical traces (ytterbium!), don't seem to concur.
The suggestion that appears to satisfy the most data - still not all - posits 2 huge and powerful spacecraft, both turning to converge at the explosion site, and only one continuing westward from there. Science fiction fans like this scenario a lot better than most scientists do, but it satisfies more data than any other.
The comet concept satisfies the second-greatest quantity of data.
Now that this book has taught me a great deal more about Tunguska science, I am no longer confident about any one explanation. Rubtsov is right: we don't know enough. Previous such cases include:
• discovering the constancy of the speed of light, before Relativity;
• Auguste Comte's declaration that the composition of remote stars must remain forever unknown, before spectroscopy;
• noticing fundamental parallels in living things, like backbones, before Evolution.
Enjoy this book for its rich scientific and historical narrative, its scientific rigor, and its logical structure. The book is well written, well edited, and well produced. There's just enough Russian syntax to suggest local flavor. But if you want The Answer to what hit Tunguska, it's not here, nor anywhere else. Yet. Check back later.
J. Allan Danelek: The Great Airship of 1897: a Provocative Look at the Most Mysterious Aviation Event in History. Adventures Unlimited Press 2009.
review © Norman Sperling, February 10, 2013
A mysterious bright light in the night sky sparked this big flap at the end of the 1800s. It was unexpected and unexplained. Reports grossly contradict one another, so investigators can favor very different inferences, interpretations, and explanations simply by selecting different reports to prefer.
In the 1800s, no one considered the light to be a space ship from another planet. Paranormal boosters have made that case more recently. Since this book's author energetically investigates paranormal and Fortean matters, I was all prepared for the author to go Paranormal.
He never did. The one place where the paranormal is invoked by others, Danelek dismisses it tersely. This book has nothing at all to do with the paranormal. Every explanation is purely naturalistic. Danelek invokes real physics, real engineering, and common human nature. At every turn, Danelek reports what records show, and points out contradictions and gaping ignorance. He discusses assorted possibilities.
He selects reports that can be strung together into a consistent story, and says that's why he prefers those. The data are so sketchy that there is lots of room for speculation. Danelek offers several speculations, but clearly labels each one as it comes up. Danelek builds a case that it was a searchlight coming from a lighter-than-air dirigible-type airship.
Astronomer Charles Burckhalter, among others, said the "searchlight" was actually the brilliant planet Venus, which dominated the western sky in late 1896 and early 1897.
Danelek ties his case together in a fictionalized story, which he blatantly labels as fiction at both its start and its end. A few readers may deplore putting fiction in this book, but as long as the reader can tell what's fiction, that's fine. In fact, my motive to read this book was to see if I could adapt part of its story for astronomical fiction that I'm writing. I can.
The illustrations are quite clear and plausible. The editing is not as sharp as the writing. Several misspellings got into print. A sharper editor would have squelched several redundancies.
Overall, this is an interesting, entertaining, and rational book. It shines some light on a bright light of long ago.
© Norman Sperling, January 9, 2013
In teaching astronomy, I not only have to teach many very strange concepts, I also have to deal with the very strange terms that Science uses for them. Over the years, I've learned that students find it harder to learn the words than the concepts.
When confronted by a strange term, a student will learn its definition and keep that in mind.
When confronted by a second strange term in the same field, the student will learn that definition, too, and keep it in mind.
Sharp students can even keep in mind the definition of a third strange term.
But that's the practical maximum. If you try to teach them a fourth strange term, their circuits go on "overload", they freeze, dump all 4 definitions, and regard your subject as "confusing" and therefore "too hard to learn".
So I minimize strange terms. The students benefit any time I can substitute plain English for a technical term.
Some are avoidable. Some are not. I can talk plain-English around a lot of astronomy. "Cliffs shaped like curlicues" works way better than "lobate escarpments" on Mars. "Layering" works better than "stratification" on many solid objects. "Mindset" works well enough for "paradigm". But I still use "nebula" because neither "space cloud" nor "hydrogen-helium cloud" conjure up the right concept in students' heads.
Where the astronomical term describes something entirely beyond human-level experience, no conventional term does well enough. "Nuclear fusion" is NOT "burning" - burning is much weaker, a chemical reaction in electron shells.
© Norman Sperling, December 26, 2012
Part of a set on the Voynich Manuscript:
Great Stories from a Book You Can't Read: The Voynich Manuscript December 23, 2012
Voynich: Turkish? December 24, 2012
Voynich: 2 or More Handwritings? December 25, 2012
Could 2 of Voynich's Oddities Cancel Each Other Out? December 27, 2012
Did Voynich Swindle Mondragone? December 28, 2012
Would You Like to Buy a Copy of the Voynich Manuscript? December 29, 2012
William R. Newbold's 1921 contention that the spiral graphic in folio 68r represents a spiral nebula is wild bunk. The spiral nebula concept was suggested to Newbold by astronomer Eric Doolittle, who really should have known much better. Doolittle was a diligent and much-appreciated expert on double stars, but at f/20 his telescope gave some of the poorest, faintest, least-contrasty views of nebulae (the category from which galaxies had not yet been separated). To be blunt, Doolittle was out of his specialty and didn't know what he was talking about.
While the Great Galaxy in Andromeda is visible to the naked eye as an oval smudge, it does not look spiral through even today's visual telescopes. It doesn't even appear face-on, but is strongly tilted to our view. It was first recognized as a spiral in 1899, by pioneering astrophotographer Isaac Roberts: "[the object is] a left-handed spiral, and not annular as I at first suspected". Photographs of Stars II, p63. Newbold's own book says as much (William Romaine Newbold, edited by Roland Grubb Kent: The Cipher of Roger Bacon, University of Pennsylvania Press, 1928, Chapter XI, p 123).
The very first time any celestial object was recognized as a spiral was 1843, using the world's then-largest telescope, Lord Rosse's new 72-inch-wide "Leviathan of Parsonstown". Even with highly improved telescopes in the 2010s, visual observers are hard-put to distinguish spirality in the highest-contrast, most-vivid spiral - the Whirlpool galaxy in Canes Venatici, M51 - with any telescope narrower than 12 inches. Even then, the focal ratio must be f/8 or less to concentrate light enough. Early-1600s telescopes by Lippershey, Galileo, and others were less than 2 inches wide, and typically f/20-f/40, with notoriously imperfect lenses that smeared light around. For a deeper explanation of focal ratio and surface-brightness, read my essay Of Pupils & Brightness. NO primitive telescope of the Renaissance, let alone some speculated pioneer of the Middle Ages, had the slightest chance of revealing spirality in any object, to any observer, under any conditions.
Newbold speculated about the changes a nebula might show over the 650 years from Roger Bacon's time to his own. We now know that the spirals are galaxies, so wide that light takes tens of thousands to hundreds of thousands of years to traverse them. The sharpest photographs of the last century have not revealed any measurable rotation. The only changes are sudden appearances of supernovae, which fade back down. The spiral in 68r is NOT a galaxy.
© Norman Sperling, December 23, 2012
According to my students:
Aristotle believed that the Earth was geocentric.
[Kepler's Law #] Two: Plants move fasters when they are closer to the Sun and slower then they are far away. Third: The period squared equals the semi-radius cubed.
Comets were initially fussy and difficult to see.
Plates "smash" into one another in a subversion zone, like along the Chilean coast.
Volcanoes ... become dormat.
Black holes are prominent in the solar system, but widely misunderstood.
The Big Bang theory states that the death of a star created our galaxy.
the "emberrs" of the Big Bong
The Big Bing was the creation of everything as we know it.
[Let us know when Microsoft's search engine starts listing that one.]
© Norman Sperling, November 19, 2012
For half a century I've built my library. First I accumulated all the astronomy references I could get. Then I expanded to history of science. More recently, science humor and science travel.
I read many hundreds of them. I use their old illustrations in my courses and lectures. I traced the development of ideas over centuries using long shelves arranged by date.
And now it's time to sell off most of the ones I don't expect to ever use again.
I'm keeping books that
1. I like (usually because of what they say, sometimes how they look)
2. I have a story about (occasionally negative)
3. I expect to use
Not all the books that I price will sell right away, so I'll still have those for a while.
I'm also putting off selling books autographed by living authors. I got almost 400 volumes autographed, but I did so for myself, not for resale value. I wouldn't want any authors to think I got their autographs just to raise the resale price a few dollars. Since it's hard to hurt the feelings of deceased authors, it's OK to sell those autographs. Books that I bought already autographed are fair game, of course.
For pricing, I seek the median for used copies presently listed online. I add a bit for rarity and autographs and great condition. I subtract a bit for worse condition and commonness.
If a book is rare, I say so on the tab. Or "uncommon". Sometimes I think to myself "deservedly rare", though I don't mark "unimportant" or "undistinguished" or "dull" even when that's what I think.
If I don't like a book, or its author, and want to sell fast, I'll cut the price markedly. Just now I thought "I never liked this book" so I said that on the price tab, and marked it 1 cent. Years ago I had a book I couldn't stand, but couldn't stand to dump into recycling, either. I taped a nickel to it, with the statement "Here's 5 cents if you'll take this away." Sure enough, someone did, with a grin.
© Norman Sperling, October 29, 2012
No, I didn't make 100 enchiladas, the tasty Mexican food. NCHALADA - pronounced the same - is the Northern California Historical Astronomy Luncheon and Discussion Association. It's an informal group, meeting 3 or 4 times a year since 1985. No charter, no bylaws, no dues, and between meetings it only exists as a mailing list.
With Ron Oriti, I co-founded the group as Northern California's version of the "Society for the History of Astronomy", which conducted discussions around Los Angeles. Ron was active there while working at Griffith Observatory, and I visited one excellent session hosted by Gibson Reeves.
We thought the same kind of thing might work around San Francisco. We were right. Meeting mostly at Chabot Observatory, and its successor Chabot Space and Science Center, we discuss a very wide range of topics, some timely, some timeless.
Each meeting selects topics, chairs, and dates for the next. Where a different venue is wanted, or needed, we take offers, or find a suitable place.
Discussions are always good-humored, with many a pun (by many participants, not just me).
But the characteristic commented on repeatedly is that participants bring strong mindpower and expertise, and join in purely for the intellectual joy of it. Bob Multhauf said he enjoyed NCHALADA meetings more than academic colloquia because no one was trying to impress an advisor or potential employer, they were all there because they're interested. A high-ranking MD said NCHALADA discussions show stronger brainpower than he finds in professional meetings.
Attendance has dwindled. The Los Angeles group gave up several years ago. Our attendance has drifted downward, though meeting 100 brought a dozen, our best total in a while.
-- == 100 == --
Nancy Cox, Alan Fisher, and John Westfall have attended about 90 of the 100 meetings. And I have attended every single one.
I was wondering if I could make it. I normally don't make a big issue of numerical milestones, but I've been hoping for this one. Would I still be in town? Though I reconciled myself to missing some because of my upcoming travels, the group picked meeting dates for when I'm home. Would family, health, and other considerations allow it? They never got in the way. The next meeting or 2 also look possible.
-- == Historical Astronomy On Line == --
We just set up an online Yahoo Group to resurrect our former website in an easy format, spark discussion between meetings, and encourage people everywhere to consider our topics. It's also an invitation for more people to join discussions that interest them.
We're posting many of our previous "discussion suggestions" of varying strength. They may include essays, bibliographies, and/or questions. Bringing up a topic is NOT the same as agreeing with it, and participants discuss it from many different viewpoints.
If other places wish to conduct sporadic or regular discussion sessions, we applaud. If you would like to link to any of our postings, please do. If you would like to adapt some, please ask its author, but it'll probably be fine. If you would like to contribute questions, bibliographies, or essays in historical astronomy, send them to us and we'll probably want to post them unless they are offensive.
© Norman Sperling, September 20, 2012
Part of a series on Educational Star Parties:
Star Parties Designed for Students (July 7, 2012)
7 Spectral Types in 1 Big Loop (April 15, 2012)
Telescope Triplets (November 25, 2011)
At observing sessions, students and the public hear a whole lot of information, but don't keep notes, nor remember it too sharply. Remembering the data shouldn't be the main thrust anyway; seeing the objects is.
Prepare telescope trading cards, and object trading cards, to give to all comers:
* On each scope card, show a snazzy photo of the scope, its statistics, interesting background, and its proud owner/operator.
* On each object card, show a visual impression resembling what the observer actually sees; plus a more impressive astrophoto; the object's statistics, and interesting background. Include major catalog designations and nicknames.
Prepare plenty of these cards so scope operators and volunteers can hand out the right ones. Cards should hugely reinforce the educational experience, giving a tangible card to show to others (encouraging them to come); keeping the information from getting pathetically garbled; and reminding visitors how well they observed.
Kids already have LOTS of trading-card display sheets, boxes, and so on. They can handle the cards. And parents ought to strongly encourage these cards. Cards should cost a few cents to produce, are cheap and easy to update and replace, and easy to generate anew. It might cost a buck a kid for star parties and most musea, but should pay dividends in post-visit appreciation and word-of-mouth promotion.
All-day visitors to a big museum could amass a couple dozen cards, if they are given for every planetarium show and exhibit. They'll remind visitors for years of their visit. Visitors to other venues might get cards for flora, fauna, minerals, and cloud types along the way. Perhaps each hiking trail could have one, or even each "look at this" post.
Where attendees have smartphones, give them digital versions instead of cardboard cards.
© Norman Sperling, August 21, 2012
For the first time in many years, I attended a major, many-night-long star party. Hundreds of amateur skywatchers set up their telescopes and auxiliaries for nights of dark-sky observing at the Oregon Star Party, east of Prineville.
Their standard array is far more advanced than I remember from 30 or 40 years ago.
It starts on a ground-cloth: a tarp or a sheet or a tablecloth. Some are thin carpeting. Light-colored carpeting would make it easier to find things in the dark. Decades ago we set up in grass, and wasted a lot of time hunting important little things we dropped.
The telescope and several auxiliaries now consume so much electricity that observers lug out a battery, such as a small car would use. Wires from the battery to the equipment are sometimes neatly tied, sometimes run hazardously wild. Sometimes the battery tucks under the scope, inside a tripod leg. Decades ago very few observers had separate batteries, some tapped their car batteries, and most didn't use any electricity.
Tote boxes and padded equipment safes often sport custom-cutouts for specific eyepieces, et al. Most sites had 2 or 3 boxes and some had more. Decades ago observers had a lot fewer eyepieces, and all of those were much smaller than today's huge, massive marvels. So one simple container was all anyone needed.
Almost every site has a folding table or 2. Portable tables have been reinvented, with many patterns and sizes available from discount stores and outdoor outfitters. Some have roll-up table tops. Since the tables carry little more than laptop computers, atlases, and notebooks, light-duty hardware is OK, verging on flimsy. Decades ago the few who brought tables used card tables. We spread atlases out on car hoods and trunks, which were more horizontal then.
Everyone uses folding chairs. These, too, have been reinvented in profuse variety. Decades ago the only types had a flip-down seat as can still be found in schools and churches, and plastic-webbed aluminum-tube lawn chairs.
Tall Dobsonians became popular in the 1970s, and used the teetery ladders of those times. Now far more common, they use newer ladders with safer, wide-splayed feet.
I saw a few "anti-gravity" chairs for binocular use and meteor watching. Decades ago we had plastic-webbed, aluminum-tube chaise lounges.
Everything is carefully folded or furled to fit their vehicle ... or, the vehicle is chosen because it can hold the owner's full set. I remember marveling at how much more a squarish van held than a conventional station wagon. Now, vehicles come in so many configurations that everyone can carry everything they want. A lot of RVs at the star party showed red-light and sealed-window customizations, so many people are very serious about this.
The 2012-era scope site sports a great deal more stuff than its predecessor. The scopes themselves cost a lot more, and so does all the other stuff, and their vehicles. But the expense and the bulk deliver images far surpassing those of olden times, and computer-processed electronic imaging vastly exceeds old film astrophotography. They get what they pay for.
© Norman Sperling, July 7, 2012
Part of a series on Educational Star Parties:
Trading Cards for Telescopes and Celestial Objects (September 20, 2012)
7 Spectral Types in 1 Big Loop (April 15, 2012)
Telescope Triplets (November 25, 2011)
I'd like my astronomy students to attend a star party that's designed for their education. They would see a richer variety of sights than at a star party intended for public enjoyment. An educational star party would be located for dark skies more than easy access. Students would observe over about 2 hours rather than 20 minutes. They would look through a greater variety of telescopes (educational in itself) at planned sequences of objects.
Designate part of the open field for naked-eye use. Have a teacher showing constellations and asterisms, and teaching skycraft. Show the Milky Way. "Earth" is a freebie: just look beneath your own feet.
Pre-plan and shout-out the appearances of satellites (especially the Space Station) and Iridium flashes. Keep alert for sporadic or shower meteors.
Select telescopes optimized to give the best views of:
* Each visible planet ... including, by popular demand, Pluto. About half are up at any time. Scope operators should point out noticeable moons.
* The Moon. One scope with a whole-globe synoptic view, followed by one with a high-magnification view near the terminator.
* Asteroids that are "up": Any that are labeled "dwarf planet"; major spectral classes S, C, and M; classes V and G because the Dawn spacecraft visits Vesta and Ceres; whatever other bright ones are available.
* The brightest comet that's up, even if very faint.
* Stars, by spectral type, as I described in 7 Spectral Types in 1 Big Loop, plus telescopes pointed at a red dwarf and a white dwarf.
* Multiple stars, preferably color-contrast
* Open cluster
* Globular cluster
* Pre-stellar nebula
* Planetary nebula
* Supernova-remnant nebula like the Crab
* HDE 226868 or another indicator of a black hole
* Elliptical galaxy
* Spiral galaxy
* Interacting, distorted galaxies
* Active galaxy like a quasar (3C 273), BL Lacertid, or Seyfert.
* Galaxy cluster
Assigning specific scopes to specific objects requires attention to available focal ratios, apertures, eyepieces, and the personalities of their operators. Depending on how long it takes the gathered students to see an object in each telescope, scopes can be re-pointed to other planned objects 2 or 3 times during the session. Several targets require fat light-buckets. 1 or 2 could handle them all, in sequence, during a 2-hour session.
The Telescope Triplets I advocate can also teach how telescopes and eyepieces affect the view.
The Trading Cards for Telescopes and Celestial Objects I advocate should be pre-planned and heavily distributed.
Asteroids, dwarf stars, several deep-sky objects, and galaxy clusters look tiny and faint. These teach the students to appreciate the views from giant observatories.
For this rich an experience, students could buy $5-$10 tickets. That should cover venue expenses plus honoraria for amateurs who bring their own scopes. Teachers would give credit for attending and filling out observing logs.
Most students can afford a $10 ticket. They would pay that for a night's entertainment anyway. It's similar to the expense of driving to the dark-sky site. They can save more by buying used textbooks instead of new. Someone may want to quietly handle "scholarship" discounts. The event definitely will cost something to run and that needs to be raised.
Cooperating instructors might be able to organize this kind of event, especially if they have access to appropriate scopes and operators, both student and amateur. Here in the San Francisco area, The Astronomical Association of Northern California might be able to organize it. It could also be a commercial venture.
Though designed for students in introductory astronomy courses, such a planned, organized star party should attract many amateur astronomers, and some of the public.