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Star Parties Designed for Students

© 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.

The Straight Dope on the Straight Wall

© Norman Sperling, June 29, 2012

Technology has now improved so much that a coordinated observing campaign can reveal important new data about one of the Moon's most important features: The Straight Wall.

First, data-mine all spacecraft observations, including Chinese and Indian. Face-on, sunlit views from spacecraft should be able to identify distinct layers. I haven't heard of anyone specifically researching these about the Straight Wall.

Monitor the Moon from Earth, using high-magnification, high-resolution imaging, especially of sunrise and sunset along the cliff. Use several widely separated instruments, so that there should always be at least one with good weather and the Moon high enough in its sky. This requires global coordination. That would have been very unusual 30 years ago, but is clearly possible now.

Extremely detailed sunrise and sunset animation sequences, from different librations, should reveal nearby faulting, or prove there isn't much.

Use the animations to map the slope and its component boulders. Precision measuring at sunrise and sunset, boulder by boulder, should determine elevation as well as latitude and longitude. I predict the boulders should be very large compared to Earth's talus slopes. That's because the rocks should be about as strong as similar Earth rocks, but the Moon's lower surface gravity exerts less force to break them up.

Spectral differences should distinguish between pieces from the top stratum and pieces from lower strata, hopefully corresponding to understandable mineralogical differences between strata. Infrared observing after sunset might reveal different cooling rates, further revealing differences between boulders.

Examining the buildup of dust at the bottom will tell something about dust scattering rates (such as by electrostatic levitation on the terminator) since landslides.

All this is possible with the latest generation of electronic imaging and enhancement. It's time to try.

The Core of the Problem is the Problem of the Core

© Norman Sperling, April 30, 2012

The media made a big hullabaloo over the public announcement of forming a company to mine near-Earth asteroids.

In several ways, the announcement sounded right:

* Launch a fleet of spectroscopic telescope satellites to "scope out" potential targets. Wise!

* They distinguished between icy and heavy-metal asteroids, and mentioned the potential values of each. Correct.

* First, target the icy, primitive asteroids (types C, P, D, and probably K) because their ice can make rocket fuel. So far so good. They're also abundant, contain the widest variety of minerals, and are the loosest-bound, so they should be easiest to mine. But the "rare earth" metals are pretty skimpy in these asteroids. Not as bad as Earth's surface rocks, but poor ore.

* Media reports recognize that minerals which are valuable because of scarcity will become much less valuable if the market is flooded. They include the concept of rationing to slow the flow. I expect that must occur naturally, because it will take time to break up and refine an asteroid. Attaching mining devices to an asteroid hardly makes the entire asteroid immediately available as refined metals.

I didn't see the media discuss another big factor, which is both an asset and a liability.

Metal asteroids (type M) are remnant cores of formerly-larger planet-like bodies. They accreted so much that they heated up. They get heat from collision, sunlight, condensation, and the decay of radioactive atoms inside. As long as they're small, they radiate heat out faster than they collect it. But bulk acts like a blanket, so once an object builds up to more than a few hundred kilometers in diameter, it can't dump heat as fast as it builds it up. If you don't mind a sip of technicality: that's because as an object gets bigger, the volume (in which to generate and hold radioactive heat) grows as the cube of the radius, but the surface (from which to radiate heat away) only grows as the square of the radius.

Under the heavy pressure of hundreds of kilometers of minerals sitting on top of them, and the increasing heat, primitive rocks melt. They quickly differentiate: light stuff floats, and dense stuff sinks. This results in layers, in order of density. That's why Earth's layers are the inner core, outer core, mantle, crust, hydrosphere, and atmosphere.

Those aren't pure, refined elements. They are mixtures, alloys, suspensions, and a variety of other combinations.

Cooled-off, solidified nickel-iron outer cores are what we think we're seeing in type-M asteroids. All our metal meteorites are from those outer cores. Iron shells are probably awfully tough to break by collisions at the speeds common in the asteroid belt. But mining engineers can probably crack that problem.

The big problem comes from exposing the inner core, to which most precious heavy metals migrate. The inner kernels may be relatively small. The mix there will have every heavy element that doesn't linger up here on the surface. That's why they're the rarest up here. Those include radioactive elements with long half-lives. In other words, the core alloy must be radioactive. I saw no mention of this important factor in the company's statement or media coverage.

We don't even know which substances dissolve into one another under the conditions of the inner core. The radioactive and the quiet minerals probably make novel combinations with unknown characteristics. Non-radioactive components have been irradiated for 4 billion years. Would that induce unfamiliar radioactive isotopes?

Metal asteroids that expose some of their radioactive inner core might be detectable by that radiation. I've never seen a study relating unattributed detections of ionizing radiation to the locations of type-M asteroids. I wonder if we've already detected some, but not recognized that yet.

Surely, to extract useful minerals from an inner core will require a lot of refinement. Refining enough uranium and plutonium for bombs and reactors required building entire scientific cities - Hanford, Oak Ridge, and so on - running enormous factories round the clock for decades. Similar operations with robots, in space, will probably be extremely expensive. How would mining robots recognize and handle the radiation? Refinery hardware and electronics would have to survive intense radiation as well as extreme temperatures and vacuum. Transmutation of the robots' own atoms would change their usability.

Components for use among people on Earth would have to emit no more than background levels of ionizing radiation. What an extreme refinement!

Weird Astronomy: Tales of Unusual, Bizarre, and Other Hard to Explain Observations

Weird Astronomy: Tales of Unusual, Bizarre, and Other Hard to Explain Observations, by David A. J. Seargent. 317p. Springer 2010. $39.95. 978-1-4419-6423-6.

reviewed and © by Norman Sperling, April 26, 2012

Australian astronomy writer David Seargent knows sky-watching - a long-time amateur astronomer, he discovered a comet in 1978. He has been telling about these curiosities in a long string of articles for Southern Astronomy, which became Sky & Space magazine. He has integrated and smoothed them out well for this book. But one standard that may have been OK in the magazine grates on me! He uses exclamation points way too much!

Between exclamation points, Seargent tells these neat stories with an easy flow and a light touch. He explains things in a clear, friendly way that teaches accurately but painlessly. Collectively, they form good lessons on scientific reasoning, the importance of data quality, and understanding how the sky works. The Universe seems to show more phenomena than humans have so far commanded. The stories are very enjoyable for readers who haven't heard them before. They will certainly entertain readers interested in any science.

Seargent also inserts suggestions for projects. Every reader, from novice through expert, can find some interesting possibilities to work on.

Some items from the main chapters:
* Our Weird Moon: William Herschel noticed 3 red glowing spots on the dark part of the Moon on April 19, 1787. He thought they were erupting volcanoes, but that would have left evidence that we would now see, and we don't. Seargent points out that that very same night had intense aurora as far south as Italy, and asks if the same flow of high-energy particles hitting Earth might trigger glows on the Moon.
* Odd but Interesting Events Near the Sun, including transits and comets.
* Planetary Weirdness dwells mostly on Mars, and wonders if microbes do, too.
* Weird Meteors: Curving, zigzagging, and black meteors have been reported.
* Strange Stars and Star-Like Objects: including assorted flashes and blinks.
* Moving Mysteries and Wandering Stars: several tiny comets have been spotted close to Earth.
* Facts, Fallacies, Unusual Observations, and Other Miscellaneous Gleanings: planets and stars by daylight, the thinnest crescent Moon, odd meteorites, and the "potassium flare" star whose spectrum actually measured a smoker striking a match.

The publisher's contributions to this book aren't as good as the author's. There are several typos, though none of them interferes with understanding. While the text is printed very clearly, many of the pictures are too dark and murky, and hard to distinguish. The color pictures lack resolution. The publisher appears to have trusted a new printing technology, which seems not ready for prime time yet.

Defining any book project requires many decisions to be made. They decided this one would be "popular" rather than scholarly, so they left out all references. But this subject matter is deliberately obscure, and they give no hint as to where to chase down any item that attracts your fancy. There were many items that I could not even guess where to pursue, beyond a web-search.

But many of them I do know where to look for: Mysterious Universe by the late William R. Corliss. (Sourcebook Project, 1979). When I started wondering about those Earth-approaching comets, I checked the Corliss compendium and found 2 of Seargent's 3, plus several others, all with full quotations from the original literature. Corliss has quite a number of Seargent's phenomena. More on the personalities and places can be found in Joe Ashbrook's Astronomical Scrapbook (Cambridge University Press), a compilation of his articles in Sky & Telescope magazine. So readers have a choice: the simplest pleasure-read is Seargent's. Ashbrook's is more scholarly. Corliss reprints the original sources verbatim, retaining all the original information and flavor ... sometimes stuffy. Also, Corliss never tells how a story came out: were the observations flawed? Did they start a new paradigm? Seargent can solve scholars' problems by posting his references on a website.

As expected, Seargent finds more articles in the British heritage, Ashbrook in the American. This leads me to wonder how badly culture and language still inhibit communication. What curiosities have observers logged in other languages? Can we get those correctly translated, compiled, indexed, and entertainingly narrated? What percentage of the total do these English-language sources contain? How can readers of lots of other languages become familiar with these?

Corliss compendia cover most sciences. Seargent has now published one on meteorology. Do other sciences have corresponding light-reading books of curiosities like Seargent's or Ashbrook's?

7 Spectral Types in 1 Big Loop

© Norman Sperling, April 15, 2012
Part of a series on Educational Star Parties:
Star Parties Designed for Students (July 7, 2012)
Trading Cards for Telescopes and Celestial Objects (September 20, 2012)
Telescope Triplets (November 25, 2011)

When I teach about stars, the 7 main spectral types usually seem rather abstract. I show their different spectra, but that's hard to relate to what students actually see in a starry sky. I show Planck curves and explain how surface temperature results in color differences that you can actually notice. Star colors aren't the sharp tones of advertising signs, but you can definitely notice the tinges.

Star tinges are less than impressive to the naked eye, because starlight is so dim that it mostly triggers the black-and-white-registering rod cells in your retina. Only the 20 or so brightest stars deliver so much light that they also trigger a few color-sensitive cone cells, and those only barely.

But even a small telescope collects enough light to trigger a whole lot more cones in your retina, making the colors appear appreciably bolder. So a star party that is deliberately planned for student education should use 7 small telescopes to point at a bright star of each of the 7 spectral types, to emphasize their different colors. Arrange the scopes so a single line of viewers looks through all 7 scopes in order, either OBAFGKM or MKGFABO. After everybody has seen that, re-aim those scopes to their next targets.

Yes, A and F stars really do look white, but now you appreciate how real that is, unlike an artifact of not triggering enough cone cells.

For each spectral type, at any position of the sky, you can find examples at third magnitude or brighter.

All 7 spectral types are blatant around the Great Winter Oval:
O: Mintaka and Alnitak
B: Rigel, Bellatrix, El Nath, Alnilam, and Saiph
A: Sirius
F: Procyon
G: Capella
K: Aldebaran and Pollux
M: Betelgeuse

The Great Winter Oval has many advantages. It's accessible late in the Fall semester, late in the evening; all winter long; and just after dusk well into Spring semester. Since it straddles the equator, it's easily seen from practically everywhere that people live. Only in May, June, and July is it not available - parts of it even then.

When part of the Great Winter Oval is hidden by the Sun's glare, here are some bright alternatives:
O: zeta Ophiuchi and zeta Puppis
B: Alpheratz, Algol, Regulus, Spica, and Alkaid
A: Denebola, Alioth, Mizar, Gemma, Vega, Deneb, Altair, and Fomalhaut
F: Polaris, Algenib, and Sadr
G: the Sun, beta Corvi, Vindemiatrix, eta Bootis, eta Draconis, and beta Herculis
K: Alphard, Dubhe, Arcturus, and Kochab
M: Antares, Mira, and beta Andromedae

Decrease the number of telescopes needed, and make the contrast more vivid, by showing wide, bright, color-contrast double stars:
Algieba: K + G
Albireo: K + B
gamma Andromedae: K + B
Cor Caroli: A + F

Bigger scopes show color contrast in:
32 Eridani: G + A
h3945 Canis Majoris: K + F

Don't try to add spectral class W unless you're far enough south to see the only bright one, gamma Velorum, -47 degrees. There are only about 150 Wolf-Rayet stars known in our galaxy. No others are close enough to look brighter than 6th magnitude. The biggest bunch is around the Summer Triangle.

I'll comment more on planning star parties for student education in later postings.

Remembering Norman Edmund

© Norman Sperling, January 25, 2012

Norman W. Edmund founded Edmund Scientific Company on a card table in his home in 1942. When he retired in the mid-1970s, it had over 200 employees. He died at the age of 95 last week in Fort Lauderdale, Florida, to which he had retired.

I vividly remember devouring every new issue of the Edmund catalog while I was growing up in the 1950s and '60s. The catalog always had a lot of "tutorial" segments - several paragraphs each, usually with diagrams, so the users could understand the technicalities of the equipment. They weren't particularly slanted toward Edmund products, and they taught a great many people a lot about their hobby and its hardware. Only a few catalogs (like Orion) continue to do that, though it's absolutely the best policy and should be fostered. Tutorials are NOT waste-space, and they foster brand loyalty: I trust the company that makes the effort to tell me the straight information.

I met Norm several times in the 1970s, while I consulted for his son Robert. In those years Norm kept his desk in the main office, kept a bunch of neat science-thingies around, and had appropriate input. But I also sensed that he kept his distance from daily operations, carefully avoiding stepping on toes.

What always impressed me was how nice he was. Plain, no affectations, no flaunting. And he passed all that on to the rest of his family, several of whom I met. They're all nice. They treat people well. They treated me very well. It wasn't just a put-on performance, it was genuine.

To Norman and Robert, "treating people nicely" is business policy as well as personal. While it's true that being nice to people is good customer service and good business, I think they are nice to people simply because they think that is the right way to be. I learned a lot from that.

They didn't outsource service. Callers were transferred to people who knew the technicalities they needed. Customers could get replacements and refunds.

Robert once told me "Customers will always complain. They'll complain about price, or they'll complain about quality. As long as I'm president, they aren't going to complain about quality." Which is to say, the stuff he designed, produced, and marketed would actually work well. And it did. Sure, humans aren't perfect and hardware isn't perfect, but when problems cropped up, the company tried hard to fix them, and usually succeeded.

Norman Edmund was well-respected as a leader in science business, an advocate of science education, a business leader of Greater Philadelphia, an expert fisherman, and a gentleman who "lived long and prospered". I'm really glad I knew him.

My Students, Yo Mama, and Chuck Norris

© Norman Sperling, December 22, 2011

I finally finished finals, that mad dash to pay careful attention to 60 handwritten exams in a little over 5 days. As usual, most of my students learned their material well. But the ~350 pages also harbored a few bloopers:

* Quasi-Stellar Radio Sources ... were discovered after World War II by radiologists.

* Cepheids are an example of a galaxy cluster that experiences meteor showers.

* Mars' atmosphere is too thin for gravity to hold Hydrogen to the surface. That is why we are on Earth.

* Now the Earth has a carbon atmosphere. Since there was life, it changed carbon into oxygen and nitrogen.

* A cluster of galaxies form gobular clusters. A a cluster of gobular clusters form the Universe.


For the last 2 years, I've asked my classes to regard the extremes of astronomy in current-culture terms, by turning them into "Yo Mama" and "Chuck Norris" jokes. Their offerings:

in orbital mechanics:
* Yo Mama's so fat that when we played baseball, the ball got stuck orbiting her.
* Yo Mama's so fat that she has other fat mamas orbiting around her.
* Yo Mama's so fat that she has a Roche Limit.
* Yo Mama's so fat that she has rings of her own.
* Ancients thought the Earth was the center of the Universe. They were close: Yo Mama's so fat that the whole Universe orbits her.

in Cratering:
* The real reason for impact craters is that Chuck Norris uses the solar system as his punching bag.

on the H-R Diagram:
* Yo Mama's so fat that she's spectral type W.

in black holes:
* Yo Mama's so fat that she caused a singularity and created a black hole.
* Yo Mama's so fat that she would consume a singularity.
* Yo Mama's so fat that when she throws up, she makes a white hole.
* A black hole is the region of a singularity from which nothing can escape, not even light ... except for Chuck Norris.
* Chuck Norris uses worm holes to get to work.

in the Milky Way:
* That's not actually a supermassive black hole at the center of our galaxy, that's just where Chuck Norris sets his barbells: right next to Yo Mama.

in Cosmology:
* although it is known how hydrogen, the stars and planets, and even how *we* were formed, it is still unknown how Chuck Norris was formed.
* Creation occurred when Chuck Norris round-house kicked in a vacuum, creating the Big Bang.
* The Universe exists so that Chuck Norris can exist.
* As long as Chuck Norris allows the Universe to function, we will continue to make new discoveries every day.

Going, Going, Gone

© Norman Sperling, December 12, 2011

The total lunar eclipse on December 10th gave me an experience I have only had once before, even though this was not an especially dark eclipse as seen from the Pacific and Asia.

On December 30, 1963, the eclipsed Moon practically disappeared. From the roof of my apartment house in Silver Spring, Maryland, I could see stars as dim as 5th magnitude, but the Moon turned that dark, and I had trouble spotting it with my naked eye. Through the telescope the Moon was a dark and featureless grey-blue disc.

I watched the December 10, 2011, eclipse from San Mateo, California, through a slightly hazy sky. While most of the Moon looked pretty dark about 6:20 AM, the southern fringe was quite noticeably bright. The northern edge was almost invisible, and the area in between graduated in dull reds. Within a few minutes, the lighting pattern changed quite noticeably (in total lunar eclipses, the tints always change every few minutes), with the Moon fading appreciably in the gathering dawn. The sky didn't look all that bright, but the Moon was now so dim that it was harder and harder to notice much about it. By 6:37, only the slightly-bright lower-left edge could still be found, fading like the grin of a Cheshire cat. By 6:42, I couldn't even see that any more. The sky was brightening so much that the Moon was no longer visible with the unaided eye. The Full Moon disappeared from me again!

Telescope Triplets

© Norman Sperling, November 25, 2011
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)
Trading Cards for Telescopes and Celestial Objects (September 20, 2012)

For decades, I have been proclaiming that focal ratio is one of the most important characteristics in choosing a telescope. Most authorities tout aperture instead. But none of us has ever conducted a true visual test, isolating the variables of focal ratio, aperture, and eyepieces.

I propose that 3 triplets of Newtonian telescopes be made to demonstrate the effects of focal ratio, aperture, and eyepiece. They can be used for classes and at star parties to teach about the properties of the telescopes themselves. Mount each triplet so that viewers can easily shift among all 3 eyepieces to instantly compare views.

The "focal ratio" triplet should consist of 3 telescopes, all with the same aperture and eyepiece. Make one f/5, another f/10, and another f/20. For this triplet, I think 3-inch (76 mm) apertures are best: even the f/20 would be a manageable 5 feet (1.52 m) long. Users will see that Jupiter looks best at f/20, and the Great Andromeda Galaxy best at f/5. Trying this battery of telescopes on the sky's enormous variety of targets will probably reveal very few objects that look best at f/10.

A second application of this same telescope set will use different eyepieces that all result in the same magnification: a long eyepiece on the long scope, a short eyepieces on the short scope, and a middling eyepiece on the middling scope. How different are the views of different targets?

The "aperture" triplet should consist of 3 telescopes, all with the same focal length (perhaps 4 feet = 1.22 m) and eyepiece. Make one 3 inches (76 mm) aperture, the second 6 inches (152 mm), and the third 12 inches (304 mm). Users may be surprised how much even the 3-inch shows.

The "eyepiece" triplet should consist of 3 identical middling telescopes, perhaps 4-inch (102 mm) f/8. Insert eyepieces of equal focal length but different optical designs (such as Huygens versus orthoscopic versus Nagler). A second application of this same telescope array will use eyepieces of equal design but different focal lengths (perhaps Plossls of 6 mm, 12 mm, and 25 mm ...).

Make each triplet so the scopes, and their eyepieces, can also swivel to allow 2, or even 3, different people to watch through one of the scopes at a time. This is because, perhaps once a decade, some sky event brings out throngs, and the host needs to move a whole lot of eyeballs through the scopes in minimal time.

These triplets could be built by amateur-telescope-making workshops, such as several clubs run, or perhaps by a veteran scope-maker. Most are quite small, only one is large. Try hard to hold all but one factor constant so they really test that single variable.

A whole metropolitan area probably needs only one set. Telescope triplets can be passed around among nearby colleges, astronomy clubs, planetaria, etc., to use at their classes, star parties, and member-events.

The Metric Light Year

© Norman Sperling, October 24, 2011

My friend John Westfall, an astronomer and geographer, points out that astronomy uses several non-metric units, most prominently the "light year". Officially, that's the distance that a beam of light travels, at the speed of light, in a year's time. In metric units, that's 9,460,730,472,580.8 km (about 9.5 Pm), according to Wikipedia.

While the light year is more than 5% shorter than 10^16 meters, no celestial object more than 20 light years away has its distance known within 5%. Uncertainties out there begin at 15% and quickly grow worse than 25%.

So, as far as anyone can measure, there is no difference between "100 light years" and "10^18 meters". Let's call 10^16 meters a "metric light year".

The Journal of Irreproducible Results
This Book Warps Space and Time
What Your Astronomy Textbook Won't Tell You

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