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Gravity Tunnels, Falling through the Earth

I think I stumbled across this a while back but I can't remember where. The classic freshman physics question is, assuming a uniform density for the Earth and a perfect, frictionless tunnel cut through the Earth in a straight line, how long would it take to travel between any two points on the surface of the Earth? The answer is interesting. It's the same no matter how far apart the two points are, 42 minutes.

Superball Physics!

I'm trying to catch up on my reading by skimming through back issues of American Journal of Physics when I found this one in the March issue: "Impact behavior of a superball," Am. J. Phys.

Testing Astro Video Capture in Linux

I recently picked up an older Thinkpad T400 that had Windows 7 installed. After a bit of angst, I went ahead with my plan to scrub the disk and install Fedora 21. Why the angst? Well, I had originally thought of using Windows 7 32-bit to control my older Canon Digital Rebel XT cameras. They are no longer supported by Canon and not at all on 64-bit platforms. But the T400 came with the 64-bit version of Windows 7 thought they seller did provide a 32-bit install disk. However, I already knew I should be able to get basic functionality out of the cameras with gphoto.

Teach Foundational Language Principles (CACM May 2015, pp 30-31)

The authors point to teaching programming languages as opposed to logic as being a seriously weak spot in computer science education. While the “Hour of Code” has a lot of appeal and can introduce people to computing, they point out that new computing languages are continuously being developed to try to solve new problems. They make numerous examples and point to Dijkstra's classic “Go To Statement Considered Harmful” as examples of how understanding a problem has lead to new languages and new language structures.

Education: What Are We Doing When We Teach Computing in Schools? (CACM May 2015, pp24-26)

This article initally caught my attention with it's graphic and caption “SCIENCE:Gravity makes haveier things fall faster.” The author goes on to recount her experience with just such a poster in a local elementary science fair and her lack of success in having it taken down. The point: we have started pushing instruction of computing (and programming) into schools where there are non-specialist teachers who are expected to understand the material well enough that the students come away with correct knowledge. 

Really installing Oracle Java on Fedora

This has nothing to do with astronomy at all, but I can't find a goo place to save this information. So...

If you're trying to install Oracle's Java on Fedora, after you've done,so, the following will set up all of the alternatives links you want/need

Feeds Updated

A lot of the incoming RSS feeds were dead, so I spent a couple of hours today to find replacements. This is as much for me as for you so I have one place to go for my space and astronomy news. I need to put togther another physics set of feeds, too, then I'm good.I also finally took the time to get the image links working correctly. The URL rewriting was a bit finicky and things had to be done in the right order, but it all appears to be working now.

So what exactly has happened to this site....

I've clearly been on a long hiatus from posting here, largely because life has a way to doing that to you from time to time.... I've still be out doing some observing, playing with equipment, and more. But I have two teenage boys now and have taken on the role of Scoutmaster in a local Boy Scout troop. The side effect has been limited time for astronomy and some equipment that is languishing from neglect.

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