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Norman Sperling
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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.

Rejectomancy

© Norman Sperling, April 7, 2012

At FogCon last week, I listened to a panel about writers getting rejected. Of course everybody hates rejection, but practically all writers endure a whole lot of it before their stories start getting accepted.

"Rejectomancy" is the writers' art of divining why a story was rejected. The editor doesn't always say, and the reasons given aren't always the whole story.

Some editors, tired of tedious editing, won't correct bad grammar to take a good article. I'm willing to "clean up" an article if I think readers would like it. I'm also willing to format in our admittedly-quirky style, rather than forcing writers to do it just for this one magazine ... which might reject their article anyway.

I asked the writers what a rejection note should say. The responses came fast, furious, and emphatic:
* Tell what would improve it.
* "Do these 3 things and I'll buy it."
* "Please send more", but only if you really mean that.
* Tell them if they're close, even if that makes rejection feel worse.

The most emphatic point, which I really needed to hear: decide FAST. I'm terribly guilty of not getting to submissions. So instead of writing up this blog post right away (I'm also behind in blogging) I'm digging into JIR's undecided submissions. It's pretty easy to recognize the 2/3 of articles that are good for JIR. But now I should explain rejections, with constructive advice. A few are "This isn't Science humor, which is what The Journal of Irreproducible Results is about." The others take some explaining.

If you've submitted something to JIR and I haven't responded, rattle my cage, and I'll get to it really soon. normsperling [at] gmail.com.

Spring 2012 Conventions Where I Might See You

by Norman Sperling, March 18, 2012

It's always great to meet readers and people with things to say. I'll be at these public conventions this Spring:

FogCon, March 30-April 1, Marriott Hotel, Walnut Creek: reading a selection, Santa Rosa Room, 9-10:15 AM March 31st, along with science fiction writers Alyc Helms and Andrea Blythe. http://www.fogcon.org

SkeptiCal (skeptical of pseudoscience) April 21, DoubleTree Hotel, Berkeley Marina. Sales table. Very interesting program! register at http://www.skepticalcon.org .

MakerFaire, May 19-20: Sales booth. Enormous, spectacular convention for do-it-yourselfers and many allied categories. San Mateo County Fairgrounds. http://www.makerfaire.com.

BayCon, May 25-28, Hyatt Regency Santa Clara: panels to be announced. http://www.baycon.org .

Teaching to the Test Kills Your Dog

© Norman Sperling, March 17, 2012

When passing a test makes a big difference, instead of teaching a whole subject and its importance, teachers often focus on "teaching to the test": teaching students to pass the test. If the test accurately represents what it's supposed to, that's close to OK. But tests often don't test what they're supposed to. Sometimes it's a portion of the intended material, in which case the students learn part but not enough to make it all stick together as the intended whole.

And sometimes the test just tests a proxy. The test for protein content of dog food is such a test. It doesn't actually test for protein. Instead, it tests for the amine radical, which is abundant in protein. But that's also found in cheaper substances. Twice now, without looking for it, I've come across instances where the protein test was faked by major, large-scale, planned substitution of harmful, cheap amine-bearing materials.

In the mid-1980s I was told of a dog-food manufacturer which drenched its food in ammonia to pass this test. Ammonia is a smelly poison. The dog food passed the test, though it lacked much protein. Maybe the ammonia dissipated by the time the product got to the dogs, so maybe they weren't poisoned, but they weren't fed the intended, test-certified protein, either.

And in 2007-2008, the big melamine bulk-up turned out to have been deliberate. The "amine" in "melamine" would be measured as if it were an indicator of protein, instead of an indicator of polymer. Melamine is largely inert, which is why it's so popular for dishes. But in doses large enough to substitute for protein, it poisons dogs' kidneys.

Who would do such a thing? One whose ethics see only as far as passing the immediate test, and not as far as the long-range, overall purpose. One who only teaches to the test.

It's way past time to update the protein test.

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

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