Al Petterson's Journal|
[Most Recent Entries]
Below are 20 journal entries, after skipping by the 20 most recent ones recorded in
Al Petterson's LiveJournal:
[ << Previous 20 -- Next 20 >> ]
[ << Previous 20 -- Next 20 >> ]
|Monday, September 24th, 2012|
A few notes before I begin my list. This is boring history and dry info; skip it if you want.
Saturn is about ten times as far from the Sun as we are - that is, close to a billion miles away. It takes thirty years to go around the Sun. Its axis is tilted, like Earth's is, which is why we can see its rings. It's about nine times Earth's diameter - about seventy thousand miles across.
Galileo was the first to see Saturn's rings, but didn't know what they were. Christiaan Huygens figured out what the rings were, and also discovered Titan, Saturn's largest moon. Giovanni Cassini discovered four more of Saturn's moons, and was the first to see that the rings had a gap in them (the Cassini Division). All three of them did their work in the 17th century.
Better telescopes showed us four more moons over the next 250 years, but until 1977 they were points of light in telescopes - we knew their rough sizes and masses, and of course we could watch their distances from Saturn and how long they took to orbit it, but that was about it... until we actually sent something out there to start taking pictures. We sent three flyby missions during 1978-1981 - Pioneer 11, Voyagers 1 and 2. Then, in 2004, the Cassini orbiter, carrying the Huygens probe, reached Saturn, and it's still there, eight years later. (So when I talk about what "Cassini" or "Huygens" found out, it's about the 21st-century probes, not the 17th-century astronomers.)
Some of the moons that I'm going to talk about, but not all, are "world-sized" - that is, big enough for its own gravity to pull it into a sphere. Your typical Saturnian moon orbits the planet's equator in a circular (non-elliptical) path, and keeps one face toward the planet all the time (the way Earth's moon does toward Earth). Most of Saturn's moons have no seismic activity, magnetic field, or atmosphere.
That's the typical moon. There are exceptions to every one of those rules - that's why this is so interesting to me.
The world-sized moons of Saturn, in order of distance from the planet, are: Mimas, Enceladus, Tethys, Dione, Rhea, Titan, and Iapetus. Except for Titan and Rhea being larger than Iapetus, that's also the order from smallest to largest. Two other moons are "borderline" whether they should get the same status: Hyperion (orbiting just outside of Titan) and Phoebe (extremely distant). tavella
mentioned that the number of Saturn's known moons has gone from about 20 last time she looked to something like 60 now. Yeah. My reaction is this. Saturn has, at least, billions of "moons" - meaning things orbiting it. The rings are made of "moons" - a mile or less in diameter, with no real division between "moons" and "ring material", except for "things big enough for Cassini's telescopes to discern them individually". It also has an undetermined but huge number of progressively smaller rocks orbiting it at extremely large distances - captured asteroids and centaurs and comets, going from barely-noticeable down to who-cares; each time telescope technology gets better we find a bunch more rocks.
They're rocks. Yeah, when we find them we give them names. But I'm not about memorizing names, not now that we know a lot more about things than their names. There are lots and lots of rocks orbiting Saturn. I'm mostly interested in the worlds
- and only interested in a rock if it shows us something as interesting as a whole world.
So anyway, that's the textbook stuff. Boring part over.
|Sunday, September 23rd, 2012|
|Saturn geekery starting
I'm going to try something. Maybe it'll totally bore you. I don't really care. :) It's not about politics - so I should get some credit at least for that.
I'm going to talk about Saturn. That is, about the parts that interest me - the parts that most people who aren't space geeks don't know a thing about. If you're like most people, you know Saturn's the sixth planet from the sun and it has rings. If you're into astrology, you might know that this year it's in Virgo; you might even know it spends two and a half years in each sign (which means it takes about thirty years to go around the Sun). If you were at any point a nerd, you know Saturn is about nine times the diameter of the Earth and it would float if you threw it into a big enough bathtub. And that's it, for most people.
None of that is particularly interesting to me. ( Read more...Collapse )
|Friday, August 17th, 2012|
I was getting a little concerned about my daughter - she'd been miserable the last couple of mornings (5:30 wakeup calls are not easy), and annoyed with herself for getting a B on her first math quiz, and muttering about how she's going to quit band next year.
So today she comes home. "So. Did you survive the first week of school?"
She starts bopping and bouncing. "Yeah! In band, first of all, it was cooler today, so that made it a lot nicer to do drill. And the three new pages of drill were tons easier. And they had this sombrero - MissK came out in a sombrero, and said she'd give it to people for doing really well at marching, and the first person she gave it to was like this sophomore who plays bari sax. And then *I* got it! Freshman me! Except then - " she starts giggling - "right then, as I put it on, the breeze started kicking up, and it started pushing the sombrero - and then when I snapped the trombone up to my shoulder, it knocked the sombrero onto the side of my head - and then when I started marching - " her giggles are almost uncontrollable - "it wound up in *front* of my face, and so I tried shoving it aside, while playing and marching at the same time, and it got tangled up in my trombone, and by then I was like five steps away from where I was supposed to be. So really the hat was all about embarrassing somebody who's good at marching." She kept laughing. "And then, in PE, of all the girls in the two freshman classes together, I did the 4th highest number of crunches. Yeah! Core!" Fist pump. "And then I did like six pushups. So yeah, core is all I've got. But sixty-six crunches!
"And then, in Spanish, I aced the test; it was so easy. And in math, we had a test and I'm pretty sure I did well, because I had time at the end to check all my answers. And there was one that I wasn't sure was right, because it was like 15/32 or something, so I went back and did it from the beginning a different way, and I got the same answer, so I'm pretty sure I did it right.." Eyes shining. Somebody had a really good day.
|Friday, July 20th, 2012|
I grieve for the families of those who died in Colorado, but it's not *my* tragedy. They're just a bunch of Americans I don't know - no different, ultimately, than if they were Syrians I don't know - and anyway, Americans are shot and killed by the dozens every day. It just usually happens one at a time, and no one hears, or takes notice, outside their immediate neighborhood and local police department, and if they're lucky an obit in the local paper. Twelve people being shot at once is the equivalent of a cute blonde girl going missing: lots of talking heads on TV solemnly pissing and moaning, the President makes a speech, and meanwhile there are roughly a hundred other American families out there who also had - or will have - a loved one shot today, who are probably wondering why they don't get mentioned by the President or make the national news.
But it's been made very clear to me that in this country nothing whatsoever can be done about this, because we're simply not any other country that doesn't have this problem, and we have a Constitution, and that's why we can't have nice things. So I guess the solution is to not care, move on, say "It's the price we pay for, um, 'freedom'," and try very hard not to think how terribly ironic that is, or how many people don't recognize the irony.
|Tuesday, June 5th, 2012|
again on Sunday (it's basically as good the second time as the first).
I want to do a "Stephen Schwartz Generic Musical" chart at some point... (cut for spoilers if you care) ( Read more...Collapse )
|Tuesday, May 8th, 2012|
There is this disorienting moment when you find a video of the high school drum line for your kids' high school - and they're doing a song for competition, and you listen to their (very good) all-percussion performance, and you suddenly realize they are playing Tom Sawyer
|Wednesday, April 25th, 2012|
I was thinking about asteroid mining, now that there are some rich people who want to do it.
"Who owns what" is a fundamental question of civilization, and how a culture chooses to answer this question is central to how the civilization develops.
And I saw a ton of knee-jerk reactions in every discussion about this. I see three very different concerns -- and I don't see anyone at all recognizing that all three concerns are valid.
If no entity can own property off-Earth - as is currently the terms of the space treaty we signed in, what, 1969 - there is a real danger that we, as a race, will never develop or make use of off-planet resources. And it is my firm conviction that we will desperately need to make use of off-planet resources.
If private entities are allowed to own property off-Earth, it is inevitable that claims to most property will be made quickly by the wealthiest among us, who will then extract rents in perpetuity. We've seen this many times before - corporatocracy and robber barons reduce everyone else essentially to serfs, or at best renters.
If only governments are allowed to own property off-Earth, I worry about the potentials for war, tyranny, and central control over humanity.
Any solution to using resources beyond our planet has to confront all three. And I'm certain that I don't trust anyone who doesn't at least acknowledge all three as real dangers.
There is of course the possibility that a representative government, beholden to the will of a free people informed by reliable experts and kept abreast of real events by aggressive free reporting, debating issues in public fora, might manage these resources in a way that avoids these dangers.
And while that seems unrealistic, it also seems (to me, so far as I have watched humanity) that - while this proposal is not wholly immune to any of the three dangers above - all other solutions I've seen so far have much more potential to fail in one of those three ways.
|Thursday, April 12th, 2012|
Setting idea: near-future 1950s-style-spaceflight campaign - mankind is spreading through the solar system; transistors work but microchips don't, so there's no Internet, no reliable robotics, all communications are analog. Inside Jupiter's orbit, the Solar System is what 1950s SF thought it was; from Jupiter on out, it's what we see it as today, with minor tweaks. In other words, the world of Lucky Starr and Heinlein's juveniles, updated.
So Mercury keeps one face to the Sun, and the dark side is awesomely cold; Venus is covered in jungle and swamp, steaming and near boiling at the equator, tropical at mid-latitudes and temperate at the poles, with dinosaur-like reptilian natives; Mars has a 300-mbar CO2 atmosphere, meaning you need a scuba mask and a parka, and it's criscrossed with canals dug by the vanished natives; the asteroids are the remains of a shattered planet.
The gas giants have enormous jellyfish-shaped floating life forms, which live for eons and carry secrets, if only we could communicate with them. Meanwhile, Io is a hot volcanic hell with sulfuric atmosphere; Europa is a pitch-dark subsurface world ocean with a thriving ecosphere; Ganymede is undergoing terraforming, with atmosphere squeezed from its rocks and energy provided by geothermal vents; Callisto is a dead world, like the Moon... Enceladus is an ice shell around a sphere of water; Titan has the survivors of an alien race that fought a war (which shattered the fifth planet as well as the moon that formerly orbited outside Titan: the dust and remnants of which formed Saturn's rings, scarred Mimas and Tethys, and left behind the fragment Hyperion, which is riddled with huge caves and voids all the way into its center... and the ice giants' moons are largely unexplored.
Frozen-sleep generation ships have been launched to Alpha Centauri, Epsilon Eridanii, and Tau Ceti, but we expect to hear nothing from them this century.
Stories could happen here, right? In the right circumstances, would it be a fun place for an RPG?
|Monday, February 13th, 2012|
|How I Spent My Three-Day Weekend
When Robert was five, I promised I'd one day take him to Meteor Crater.
It is almost eleven years later, but (thanks to my wife's organizational and planning skills) I have now kept my promise...
So - Saturday, we got up at 5 AM, piled into the car by 6, and drove straight down the large intestine of California all the way to Hollywood, which we reached by 1 PM. This detour was for Kate to visit the Holocaust Museum, since it's twenty extra credit points to visit "something associated with one of the topics in her History class", and she desperately needs the extra credit. The Museum is impressive, if small, and uses technology nicely (even if we kept wearing out the batteries on the iPhones they gave each of us to narrate the exhibits). And of course the subject matter is - well, indescribable. All three kids were, in different ways, quite moved. As were we.
After the Museum, we started driving east. I'd temporarily forgotten that "rush hour" in Los Angeles is, pretty much, defined as the period between 1952 and the invention of the hovercar. Fought traffic and rain for about two hours, then finally squirted out the San Fernando end of the basin, and in the dark drove over some completely invisible terrain for about three hours, ending in Needles, CA, where the five of us arrived at our hotel room and, after an excellent meal at the diner next door, rolled over and played dead.
Sunday morning, we got up at 6:30, had a free breakfast at the same next-door diner (more about this diner later), then launched into Forbidden Country. We'd resolved that we weren't spending a dime more than absolutely necessary in Arizona; if they want our money, they can make their state feel more welcome to people who aren't white. So - a few hours blasting down I-40 at a high rate of speed, admiring the scenery (the Mojave is *gorgeous* when you can actually see it), we got through Flagstaff and reached our destination: the second biggest hole in Arizona.
The Crater is visible from ten miles away, if you didn't know. It also has its own radio station. We got to the Crater, paid admission, and learned to our mild dismay that the hourly guided tour (a half mile walk along the rim) was cancelled due to high winds. But - we cornered the tour guide and had him give us most of the spiel, we spent a good hour going through the science exhibit (the kids were all fascinated, and there was a fair amount for me to learn, too - like the only human being to date whose remains are on the Moon). Then we walked out to the observation decks and spent a while admiring the big damn hole in the ground.
We limited ourselves to a few postcards and souvenir smunched pennies at the gift shop (see earlier Arizona comment). When done, we piled back in Rommie and headed for home... and if you know what the weather was like in Flagstaff yesterday, you know we had a bit of a surprise. We went from "hey, is that snow?" to "Josh! Wake up! The trees are covered in snow!" to "No, we cannot pull off and admire it, because in about twenty minutes they're going to start requiring chains, and we need to be at a lower elevation by then." Snow. En route to the desert - which we reached and admired some more - crossing the border with an almost completely empty gas tank, by design.
If you're ever in Needles, CA, eat at Juicy's, and order the deep-fried fettucine alfredo appetizer. Great food - more than worth my bout of indigestion later yesterday evening - much more than you'd expect from a diner. I got a little bit of the story of how they'd come to have such an awesome set of cooks, but rather than spoil the story for you, go there and ask the server yourself. It's worth the trip. So - we had a second night in Needles (which, by the way, is where Snoopy's brother Spike lives), and apart from a minor plumbing failure, not much happened till the morning.
Today we drove home - from Needles across the Mojave - holy crap that's gorgeous desolation - to Barstow, then past Edwards AFB (which caused my old GPS to temporarily lose its mind) and to Bakersfield, where we drove up California's small intestine and back home. Total distance: 1750 miles, 29 hours of driving. Not a single argument or expression of boredom - lots of good conversation, lots of good music, the kids watched a bunch of DVDs and played on their Nintendos and did homework... a wonderful Lincoln's three-day weekend. And I kept my promise to my son, finally.
|Thursday, November 3rd, 2011|
|The Communist Plot To Destroy America
I want you, for a moment, to imagine being a loyal Party member, in the old Soviet Union, maybe around the time of WWII.
Think about the way they thought, back then. The Revolution - the Manifesto - was considered self-evidently true. It would start with strikes, in which the workers would unite to protest the theft of their labor, and let the property owners fail without anyone to support them. It had to happen. All nations would eventually see a rise of the proletariat against the bourgeoisie, overthrowing capitalism, installing socialism, until the state should wither away and everyone live in the foretold Communist paradise.
But just because it was inevitable didn't mean it wouldn't get terribly unpleasant along the way. In particular, there was this big American capitalistic monster squatting over the globe, interfering with the inevitable -- in fact, being by all accounts a pleasant place to live, and in postwar years booming prosperously, and making friends. Casting you as the great enemy.
The big question, for the party chiefs, was how to undermine it. ( Read more...Collapse )
|Thursday, September 15th, 2011|
|Chrome is not for me
I installed Chrome.
1. It didn’t read in my bookmarks from IE like Firefox does.
2. It has the lousy IE9 interface, where there’s only one text entry window, and it “intelligently” tries to guess whether you typed in a website or a search term. I could get used to it, except that it was getting it wrong (local company website names were search terms instead of websites.) Far prefer Firefox’s IE8 clone interface, where the left box is for websites and the upper-right box is for search.
3. I wanted it pinned at the top (leftmost) spot on my taskbar. It kept refusing to relocate when I dragged it. Then it randomly relocated itself, multiple times.
4. I have to turn on the button for home? Really?
5. I have multiple virtual desktops. When I moved to desktop 2 and tried to run a second Chrome instance there, it complained about being unable to read my preferences.
Maybe it could ‘configure’ its way past some or all of this, but that was enough. I’m sticking with Firefox.
|Monday, July 25th, 2011|
|Pulling old content off LJ
Silkie has a decade of LJ that she's become a little paranoid about and would like to pull it down and keep it.
Short of spending a weekend flexing my html-fu and writing a perl script to pull down web content, is there anything out there that can be given a list of webpages and go fetch/save them? Of course there is, but is there as simple no-frills one I can pull down and bend?
|Tuesday, June 14th, 2011|
I'm building a D&D 4E world, and I'd like to solicit commentary from anyone interested. I think I'm going to set it up as a livejournal community, http://inf-archipelago.livejournal.com/
(currently blank) - if you might be interested in worldbuilding, or want to know more, tell me so I can invite you.
|Sunday, May 1st, 2011|
|Thursday, April 28th, 2011|
Last weekend my father-in-law taught Kate how to solve square roots longhand. He writes out 4225 and shows her - "divide it into pairs of digits, so start with 42. What's the biggest integer no greater than the square root of 42?" "Six." "Right, so that's the first digit of the square root. You write it up here, square it, subtract from 42, get six. Do you see?" Kate asks a couple clarifying questions, then nods. "Now, bring down the next two digits, just like with long division except two at a time, and you have 625. Take the solution you have so far - 6 - double it to 12 - always double it - write that to the left, and add a digit to the right - that digit is going to multiply by the entire number, to be no greater than 625. So - if it were 1, you'd have 121 x 1; if it were 2, you'd have 122 x 2. So what digit should we write?" Kate thinks. "Five!" "Exactly! So that's the next digit, and now you have 125 x 5, which is exactly 625, so you have your answer, 65."
Kate loved learning it. (Of course! Getting this kind of lesson from your infinitely cool grandpa? Win.)
Robert walks into the room. "What's going on?" "I'm teaching Kate to take square roots. We just learned the square root of 4225." Three second pause. "Oh, you mean sixty-five."
Dad later showed Robert the same method. Robert: "Why do you double the number you bring down?" Me: "Because of x^2 + 2
xy + y^2." Robert: (thinks) "Oh, right."
|Monday, April 25th, 2011|
|Tuesday, April 12th, 2011|
Robert: (grumble grumble grumble)
Me: "What's the problem?"
R: "Math STAR tests. We didn't go over standard deviations last semester. And last week when we did the math review period, Mr. [T] said that since we hadn't studied standard deviations, that we should just not worry about it. And then there were questions on the STAR test about standard deviation!"
Me: "Oh. Well, darn, you should have told me about that. I could have gone over them with you."
R: "That's okay. I got the problems right anyway. But that's not the point --"
Me: "Did you know what a standard deviation is?"
R: "I know what 'standard' and 'deviation' mean. It wasn't hard to figure out what they meant - the average difference from the mean. Besides, on the one problem, they gave four answers and only one of them was a number that was at all reasonable, so I could figure out the formula from that answer, and I used that to solve the second one."
R: "But that's not the point. The point is that if you're going to teach to the test, you should at least do it *right*!"
|Thursday, April 7th, 2011|
*blink* Reading a Diane Duane Star Trek novel, humming along, when suddenly there is a Commodore Katha'sat.
Now I desperately want to play Runequest again.
|Wednesday, March 23rd, 2011|
| TPM gives latest R polls.
The poll has Huckabee at 19%, Romney at 18%, Gingrich 15%, Palin 12%, Trump 10%, Pa*l 8%. Pawlenty, Daniels, and Santorum each got 3%, Barbour got 1%.
I stand by my assertion that none of these - save maybe
Pawlenty or Daniels - can possibly become the Republican nominee, unless they somehow become unopposed. If they have any sort of opposition, they all must crumble.
How does Huckabee answer ads that point out he furloughed murderers?
How does Romney answer ads that point out he invented Obamacare?
How does Gingrich answer ads where his ex-wife points out he makes Clinton look chaste?
How does Palin answer ads that demand she speak in complete sentences?
How does Trump - never mind, I can't stop laughing at that one.
How does Pa*l produce clinical insanity in sufficient numbers of people, even Republicans?
I mean, it's entirely possible I'm wrong about this. But I'm very interested in knowing which one I'm wrong about.
|Wednesday, February 23rd, 2011|
|Evidence you have raised your children properly
You listen to Weird Al singing "My pancreas attracts / Every other pancreas in the universe / With a force proportional to the product of their masses / And inversely proportional to the distance between them", and your children all shout out "Squared!"