Wednesday, December 31, 2008

Happy New Orbit!

As we approach to within 5 million kilometers of the arbitrary point at which we've declared one orbit of the Earth around the Sun to end and the new one to begin, I wanted to wish everyone a happy new orbit!

This year, the Sun has traveled about 0.00000144 degrees around the center of our galaxy, the Milky Way. This means we on Earth have followed our sun 6,591,881,796 kilometers through space relative to the center of our galaxy. If that starts to seem like a long way, remember that's only about 0.0007 light years.

The Earth itself has traveled about 939,955,097 km in its orbit around the Sun.

And we here on the surface of the Earth, living at about 38 degrees north of the equator, will have spun around 365.242 times since the start of the present orbit. This means that we've travelled about 11,534,832 km relative to the center of the Earth.

So, to see how much you've gotten around this last orbit, get the following:
About how far you walk in a day, times 366 and the mileage off your car's odometer, then add it to the distances above (given in miles below, since my car's odometer is calibrated in miles.)

Solar orbital travel about galactic center: 4,096,030,281 mi.
Earth orbital travel around Sun: 587,471,955.8 mi.
Earth surface travel about Earth center: 7,209,279.2 mi.

Cumulative distances (all added up) are:
4,690,711,519 miles, or,
7,505,138,430 km.
plus whatever miles you travelled personally on the surface of the Earth. Figure about 0.00078 light years. As they say, it's not the years, it's the mileage.

In the past orbit we've improved our view of the Andromeda galaxy by coming about 8,678,149,920 km closer to it. That's an improvement of about .0009 light years out of about 3 million. Our views of the Magellanic clouds has gotten worse, however, with them getting about 8.5 billion km farther away for the Large Magellanic Cloud and about 5.3 billion km farther for the Small Magellanic Cloud. The compensation is that the Triangulum galaxy, M33, is now about 6 billion km closer. So views of objects in the Local Group of galaxies gets better and better for us here in the northern hemisphere.

Happy New Orbit, everyone!

Thursday, December 25, 2008

Merry Christmas!

Here's wishing everyone a wonderful holiday. I hope you got some great computers, free OSes, preinstalled software development packages, and clean compiles with no errors and no warnings worth mentioning.

While you're preparing for the new year, you're going to need a way to keep track of the date. You could do a lot worse than to pick up a Traveller calendar. It's got great science fiction art contributed by amateurs. Not that you can tell by the quality of the art. I've seen worse--far worse--in many professional publications. I've got one hanging next to me here at my post, I'm looking at the ship Azhanti High Lightning by Andrew Boulton now.

It's been a great holiday for us, and it's not even over yet.

The last couple of classes I had my Middle School computer class playing a MUD in the classroom. We had a good time, and the kids didn't even realize they were getting educated in the process.

My high school class was finishing up their proposals for video games, it looks like we're going to have some great ideas to work with. Even some of the really simple game ideas have some interesting twists to them. When school starts up again they'll be giving their presentations (assuming they still remember what they were doing ;) and we'll be selecting the games we'll be developing once we get through some Greenfoot tutorials and some Java basics. But the high schoolers found out the middle schoolers have been playing the MUD, so I've promised them a few classes of MUD before we start programming. After we've done some Greenfoot, though, I wonder if they'll regret it. :)

Saturday, December 6, 2008

Preparing for Programming (with Greenfoot)

In my high school computer class we're starting to look forward toward next semester when we begin programming. I like to have an assignment in the first semester of class where the students prepare a document with images, tables, and such. If possible I like to make it something they're actually interested in writing. And I have them tie the paper to a presentation to the class.

This year and last year I have had that paper be a design document or design proposal for a video game. This year we're going to actually use the proposals. The students will be presenting their video game concepts to the class, they'll get feedback and an opportunity to touch up their presentations then present them again. After that we'll vote to choose which games we'll actually work on developing next semester, and form small development teams to work on them (students with less of an interest in programming and more of an interest in art will be put to work producing visual resources for the programs they're interested in working on.)

In spring semester, we're going to be programming with Java, and this year I'm adding Greenfoot to the curriculum. In the past we've only managed to do a little bit of graphics in the time we have. I'm hoping that with Greenfoot we can make graphics and sound a much more integral part of our work. I've already got the students familiarizing themselves with what Greenfoot can do, so that they don't expect to develop full 3D first person shooters in one semester of introductory programming.

I've had them visit the Greenfoot Gallery to see what others have done with Greenfoot, and we've talked about how ambitious it would be for them to develop different types of programs. I've asked them to organize their design documents to have a core functionality described in the body of the document, with possible extensions described in an appendix. So hopefully the proposals will be developed enough to be interesting without being overly ambitious.

Since I first looked at Greenfoot the materials for learning how to use it have grown. There are a number of videos added to the video library they maintain. Likewise, the other documentation has grown, and the Greenfoot mailing list is quite active.

One of my middle school students has decided to take on Greenfoot on his own outside class. He saw the link on my class website, got interested and downloaded it for himself. He needed a hand getting the Java SE JDK installed on his home system, but with some basic instructions and the loan of a disk to save him the download time he's got that running now, it seems. He's worked through a few of the tutorials, it'll be interesting to see what he produces.

At this point I intend to teach only the most basic elements of running and compiling Java programs at the command line before we jump into the Greenfoot tutorials in class. It will be interesting to see how things go. Will Greenfoot drive an interest in learning how Java works to obtain desired results in the students' programs, with learning of Java smoothly interleaving with the work in Greenfoot? Or will we hit a plateau where we have to backfill with more formalized teaching of Java before we move forward? It will be interesting to see how things work out.

Either way, we'll certainly keep it fun.

Monday, December 1, 2008

Fun with the "Sharpie Test"

Among my various hobbies is telescope-making. I'm in the process of making a Gregorian telescope right now. My daughters are also making telescopes. The older one is making her second mirror, an 8 inch f/7 for a Newtonian. The younger one is making her first mirror, a 6 inch f/8, also for a Newtonian telescope.

One of the parts of making a telescope mirror is what's called the "Sharpie Test", where you draw all over the mirror with a permanent marker (you can guess what brand usually gets used) to make sure you're working the entire surface of your mirror well as you grind it. They describe the test in detail on one of their tutorials over on

Well, I like to have some fun with my Sharpie tests, I get tired of just drawing plain old grid patterns. So I like to draw other things. Pizzas are a favorite. I also draw all sorts of cartoons on the mirror. They only last a few minutes, so it's very ephemeral as art goes.

My wife suggested I take some pictures, and after reminding me of the idea enough times I finally took pictures of a couple of my Sharpie test patterns, and now I've finally posted them. Here you go.


Cat gripping planet.

Cat on alien world.

Not all my drawing have cats, I just got more pressure into taking pictures when they had cats.