Built in the early 60s, the Arecibo Observatory in Puerto Rico is the largest radio telescope in the world, with a diameter of a thousand feet. It’s appeared in a James Bond movie, “Contact,” “The X-Files,” and any number of novels.

Numerous discoveries have been made from there, ranging from new knowledge about the planets in our own solar systems to the discovery of pulsars, the first planets outside our solar system and examinations of distant galaxies. Basically, I’m trying to say that it’s a really big deal.

Much of the motivation for building the radio telescope was actually military based—it was used to discover Soviet radar installations during the Cold War by, get this: listening for Soviet radar waves bouncing off the moon.

Nonetheless, it has also been one of the most important scientific research installations on Earth for much of its life. One of the most famous programs run out of Arecibo is SETI, or the Search for Extra-Terrestrial Life, which analyzes data from the telescope to try and find any alien radio signals.

You can actually help with that through SETI@Home, a computer program that lets SETI use your computer remotely to help perform calculations. I’ve been running it for years.

In recent times, the observatory has faced significant funding troubles, though it is managing to hold on and continue performing a bunch of worthy scientific work.

If you’re ever in Puerto Rico, you can actually visit the radio telescope. Though you can’t enter the labs or the various work spaces, there is a visitor center that provides a view of the dish, and is filled with interactive displays and exhibits. I went there once; it was definitely worth the trip.

Here’s a fascinating gallery of photos from the construction of the Arecibo radio.

Good roads are absolutely essential to civilization. Many of the most successful countries in history were hugely dependent on their roads for their success. To my mind, the two ancient civilizations with the most impressive road systems are the Roman and Incan Empires.

The Incan road system, the shorter of the two, was still more than 20,000 miles long. The Incans did such a good job that much of the road is still useable today—even segments that haven’t seen a lick of maintenance in four centuries—though more than 75 percent of it has been destroyed by Spaniards and modern construction. The Incan roads were heavily used by the Chasquis, a network of runners that sent messages and valuable, lightweight goods across the empire, using relays. The individual Chasqui ran as much as a hundred and fifty miles per day through the mountains—that’s six marathons. The roads were also used heavily by normal traffic: trade on alpacas and llamas, etc.

Ancient Roman Rest Stop?

Rome’s roads are, without a doubt, the best known of all ancient road systems—not surprising, since it’s the best known ancient civilization of all time. There were 250,000 miles of roads in the network, an order of magnitude larger than the Incan network.

It’s not to say that the Incan network wasn’t an incredible piece of engineering and architecture; it was, but the Romans were just utterly obsessed with road building. There is an astonishing number of these roads still in use, whether covered in modern construction or even in their original form.

Yes, roads are an absolutely elemental part of civilization. I should put this all into perspective, though. America has nearly four MILLION miles of roads. Our population dwarfs Ancient Rome or the Incan Empire and, of course, the American population alone is greater than that of the entire world during either of those time periods.

So, next time you’re upset about construction, just sit back and think about that before complaining. It’s a small price to pay. (Unless it’s in front of your house early in the morning. That’s just the worst.)

As I was fishing with the grandkids recently, the eldest asked me why windmills look the way they do these days, instead of the way they looked in the old days and in cartoons.

Pantigo Windmill, East Hampton

I didn’t know, so when we got home later that day I helped him look it up. I’d rather admit I don’t know something to a kid and then help him research than just make something up or just brush off the question. Plus, it helps teach kids how to learn things themselves.

The answers regarding the windmills turned out to be pretty interesting, even if a lot of the math was still beyond him.

First off, the arms on a windmill are long and thin these days in order to function like a wing, which drastically increases their efficiency. So far, pretty straightforward stuff.

Next, and the most complicated: why they have three arms. Turns out there’s a whole load of math involved. A single arm would be most efficient, but wouldn’t produce much power. Two arms at 180 degrees actually puts considerable strain on the hub of the windmill, which reduces the energy it produces and causes long-term strain and damage.

Three blades solves all of these problems; using more than three starts to reduce efficiency. That’s not the only reason, of course. It also costs quite a bit more to build windmills with a larger number of blades.

The reason most windmill blades are a certain length is actually due to the shipping industry. Most of the blades are at the maximum length that can be carried by a semi on the highway. While there are some longer blades that can be transported by train and then by helicopter, they’re expensive and difficult to produce and move.

As for why windmills are painted white? My grandson actually figured that one out before we looked it up, which made me proud: The white paint reduces the heating on the windmill parts.

Plus, it just looks nice.