Real Visibility Doesn’t Require Reaching for the Stars

Visibility has always been key to situational awareness. Imagine navigating the open ocean based on what stars could be seen, and where they were in the sky. It’s a method that is accurate enough that it remained the most reliable method for determining one’s own location until just a few decades ago. Commercial jet airliners had periscopic sextants until the 1960s, and of course spacecraft still use celestial navigation, albeit the technology has advanced quite a bit.

If visibility is limited, making it difficult to see the stars, you’d be lost, right? Not quite. Visibility isn’t about seeing everything, but seeing what’s important. Out of the 2000+ visible stars, the international Nautical Almanac lists only 58 as useful for navigation. Nearly all of them are bright enough that they can be seen with the naked eye under all but the worst conditions.

Limitations on visibility come from two main sources. First, it can be too dark to see stars if weather blocks the light from coming through. However, true darkness is extremely rare, and there are usually at least a few stars visible, especially in occasional breaks in the cloud cover. Second is the opposite problem of too much light from “light pollution” in populated areas, so dimmer stars become indistinguishable from the overall glow. For example, in the middle of New York City, fewer than 20 out of 2000 stars might be visible, but this isn’t a problem: finding your location requires only a couple of measurements with the right equipment and some basic math.

From a visibility perspective, you really only need to see enough stars to recognize which one is which. In fact, adding more stars may just make it more difficult to identify what’s useful. South of the equator, the Southern Cross can be mistaken for its neighbor, literally called the False Cross. Lack of knowledge can also lead you astray: if you believe that the brightest star in the sky is the North Star, you’ll end up measuring Sirius (17° S) instead of Polaris (89° N) and end up sailing sideways.

Here are those steps, for those who want to know. (Feel free to skip this paragraph if you dislike geometry.) First, find a star you recognize, and measure its Angle above the horizon. If it were straight up (90º), you’d be directly underneath it. Navigational charts list the reference Position on Earth that’s directly underneath that star, based on time of day and year. Since you’re almost never going to be directly underneath a star, use the Angle you measured and some basic trigonometry (soh cah toa) to find your Distance to that Position. Readers of a certain age will remember trig tables: thankfully, that’s built into the navigational chart as well. Your Distance to the Position is a circle on a map, drawn with a compass (the thing that looks like giant tweezers with a point on one end and a pencil on the other, not the magnetic spinning needle). Now, do the same steps again: measure another Angle, do another lookup, find another Position and Distance, and draw another circle, which will intersect with the first one. Your location is where the circles intersect. If it’s still not clear, do it a third time, and you’ve got a single unique spot, showing you exactly where you are.

In broad terms, to know your situation, you need to know what you’re measuring (which star), what an ideal measurement would be (time becomes a reference position), how your measurement is different from that ideal (angle becomes a distance), and how that combination applies to you (your location).

At Indeni, we realize that true network visibility, like celestial navigation, is needlessly difficult if you try to measure everything possible. Like “light pollution”, too much input makes it hard to see what’s important. The best results come from knowing what to measure, because you know what every measurement means for you. That’s why our Automation Elements are created by security infrastructure experts, based on a combination of their real world experience and the vendor recommendations. By building that knowledge into our product, we’ve built a tool for security infrastructure visibility that nearly anyone can use as easily as GPS.

When discussing visibility – whether celestial navigation or network administration – if the focus isn’t on situational awareness, all you’re getting is blinking lights.