The Great American Eclipse v2.0 has come and gone, sadly without our traveling to the path of totality as planned; family stuff. We did get a report from friends in Texas that it was just as spectacular there as expected, with the bonus of seeing a solar flare off the southwest limb of the disk at totality. Many people reported seeing the same thing, which makes us a bit jealous — OK, a lot jealous. Of course, this presented an opportunity to the “Well, ackchyually” crowd to point out that there were no solar flares or coronal mass ejections at the time, so what people saw wasn’t an exquisitely timed and well-positioned solar flare but rather a well-timed and exquisitely positioned solar prominence. Glad we cleared that up. Either way, people in the path of totality saw the Sun belching out gigatons of plasma while we had to settle for 27% totality.

The eclipse also presented plenty of hacking opportunities for YouTubers in our community. Matthias Wandel went to great lengths on short notice to build a solar tracker for photographing the eclipse, while Gabe Emerson from “saveitforparts” threw his little radiotelescope rig in the car and drove down to totality to listen to the Sun during the eclipse. Jeff Geerling brought three generations along for his eclipse party, which resulted in some wonderful photographs and rubbing elbows with Destin from “Smarter Every Day.” Also interesting is this analysis of internet traffic during the eclipse by content delivery concern Cloudflare — or is that Cloudprominence? — which shows remarkable dips in internet use during totality. The dips tracked across the continent from Mexico to Canada and lined up perfectly with the Moon’s shadow.

In non-eclipse news, someone crunched the numbers on the forces involved when the MV Dali rammed into the Francis Scott Key Bridge in Baltimore, and — wow! Taking into account the mass of the loaded container ship and its change in speed during the collision, the vessel imparted something like 26 million pounds of force on the bridge. If our calculations are correct, that’s over 115 million newtons, which, as the article notes, is equivalent to 66 fully loaded semi trucks crashing into the bridge at highway speed all at once. No wonder it collapsed like it was made of toothpicks. Perhaps the most interesting thing we learned from this article was that there’s a standard reference value for the force exerted on a bridge abutment by a truck crash, and it’s 400,000 pounds.

Git is one of those things that’s so incredibly useful and so tightly integrated into our culture that it’s hard to remember what we did for source control before it came onto the scene. But source control goes way, way back, perhaps further than you realize, as this series of articles on source control systems documents. This article is the first of four parts and focuses primarily on SCCS and RCS. We were surprised to learn that source management only became a thing in the 70s when video terminals and magnetic mass storage became more ubiquitous. We’re looking forward to the second part, which covers the bad old days of CVS, SourceSafe, and ClearCase, which is where we first fell down the source control rabbit hole.

And finally, we wanted to share this fascinating video on the unlikely origins of the first desktop computer: the guidance computer of the Minuteman I ICBM. In 1962, computers filled entire rooms, but the Autonetics D-17B came in at a mere 28 kilos, a remarkable accomplishment in computer miniaturization. About 800 of the general-purpose digital computers were fielded, and when the Minuteman I gave way to other, more capable ICBMs, the decommissioned computers were distributed free of charge to universities and other institutions. The chief obstacle to putting one of these machines to work seems to have been coming up with a power supply, but once that was accomplished, a “Minuteman Computer Users Group” stood ready to help you get going.

https://www.youtube.com/embed/MJPnZzZtswc?feature=oembed