You can’t buy it at a farmer’s market, but it’s all around us. Last week I discussed I discussed the electromagnetic radiation spectrum in a fairly broad, general sense (it’s a big spectrum). Early on, I made a passing reference to natural forms of electromagnetic radiation, especially natural radio waves, x-rays and gamma rays. As I also discussed, visible light, as well as infrared and UV, are also electromagnetic radiation, but since they’re visible, I think there’s less need to really explain their natural sources.

Let’s start with conventional radio waves. Recall that these waves are typically categorized as those with frequencies ranging from about 3kHz to 300GHz. Another thing worth mentioning is that just like visible light, all electromagnetic radiation travels at the speed of light. Now, on to natural radio waves. Artificial radio waves were first discovered in the early days of electricity experimentation. As anyone who’s experimented with electricity will tell you, one of the inevitable effects is creating a spark. These early experimenters learned that these sparks actually created radio waves that could be picked up by a receiver device. Early radios used this phenomenon to function and they were often called spark-gap transmitters. They quickly fell out of use though because they tend to transmit over a very broad band, which makes interference inevitable. Earth naturally creates its own spark gaps as well during lightning storms. Just like the tiny spark gaps in early radio transmitters, a bolt of lightning will also create a radio wave, albeit a broad band and chaotic one.

The other primary sources of naturally occurring radio waves are astronomical objects. These need not even be local objects, since radio waves travel at the speed of light. The universe is pretty old, and while our neck of the woods has been relatively quiet in the past few billion years, the rest of the universe has been ??very?? busy. Our greatest local source of astronomical radio waves is the sun. In fact, all stars will give off radio waves, being the hot balls of nuclear fusion that they are. Other sources include supernova remnants, pulsars, star-forming regions as well as echoes from the Big Bang itself.

All of that stuff is just radio waves though–pretty harmless. We do study and listen to them though, to learn more about the universe beyond what we can see with telescopes. From an astronomical perspective, most of the things that generate radio waves also generate natural x-rays. Another minor source of local naturally-occurring x-rays are cosmic rays. This is where things get a bit confusing, so let me clarify some of this. X-rays as we’ve already learned are electromagnetic radiation. As such, they are not composed of matter. They are essentially the propagation of an electromagnetic field. They require no specific medium for transport (air, water, vacuum) and in the case of higher energies, can pass straight through solid materials. ??Cosmic rays?? on they other hand are not rays in the same sense. Cosmic rays are actually composed of charged particles (protons and high-energy atomic nuclei) which are physical.

Cosmic rays interact with the earth’s atmosphere and magnetosphere in a variety of ways. This is difficult to describe without diagrams, but I’ll try my best. Because cosmic rays are charged particles, they are subject to the influence of electromagnetic fields, including the giant magnetic field that surrounds the entire earth. The shape of this field (with poles situated at roughly the north and south geographic poles) channels and directs most of these particles away from the earth’s atmosphere and surface. However, particles are able to trickle down to lower altitudes at the poles. When these particles interact with molecules in the atmosphere, many things can happen, including generation of x-rays, gamma rays and other secondary particles (muons, alpha particles, electrons and neutrons). This is also what causes the polar luminescence known as the “northern lights”.

So that’s one way gamma rays can be generated naturally. Almost all astronomical sources of gamma rays (like x-rays) are screened by our atmosphere and magnetosphere. If this weren’t the case, we wouldn’t be alive as a species. Gamma rays are also generated via gamma decay of naturally occurring radioisotopes. There are even rare conditions that occur on earth that can create gamma rays including lightning strikes and so-called “terrestrial gamma ray flashes”. Both of these are the result of specific conditions in the atmosphere resulting in the availability of natural high-energy voltages. These events are particularly rare though, and are primarily of interest from a theoretical perspective. The actual amount of danger presented by these natural terrestrial gamma rays is very low. Artificial sources of gamma rays such as nuclear fission are far more dangerous because of the amounts of radiation involved.

High-energy electromagnetic radiation is not only dangerous to biological material but it can also wreak havoc on electronic systems. Semiconductor junctions are particularly susceptible to ionizing radiation (which includes high energy gamma rays). The mechanisms at work are far too complex to explain here, but on a macro level, the issue becomes that if components in digital circuitry (semiconductors) cannot be relied upon to maintain their bits (0s and 1s) the entire circuit becomes useless. In April of 2010, the Voyager 2 space probe (well out of our solar system at that point) experienced some data formatting issues. Those with more active imaginations postulated that the probe had been “attacked” by aliens, but engineers traced the problem to a single bit that had been flipped by ionizing radiation.

I think I might try to come up with a simpler topic next week, because this article even has my head spinning. Hopefully I’ve been able to at least illuminate a bit more about electromagnetic radiation for you.

It is spring break down here in Key West so the place is jammed with college kids. The beaches are crowded and so are the restaurants and bars so it is a boon for the local economy if you forget about the rowdiness. Emily is coming down next week to be one of the spring breakers. Well, okay, not really. She is coming to work on laying out the newly remodeled store here in Key West!

Meanwhile, in Vermont it is sugaring season and people are thinking about starting seedlings for their gardens. Usually, town meeting day (one of the last refuges of true democracy) is the day to start your tomato plants. Apparently, my friends in Vermont are in the typical spring roller coaster of beautiful sunny days, followed by freezing cold, followed by snow, followed by rain, followed by deep rut mud.

Thank you so much for reading this issue of Kibbles & Bytes!

Your Kibbles & Bytes Team,

_Don, Emily & Hadley_

Most of us have used and know how to search in Maps where specific locations, maybe you even use Siri to help you look up directions for places you are going. But have you ever wanted or needed directions when you did not have an address or a name of a business? On a recent vacation to Disney I had an opportunity to use Maps without having a specific address address. If you’ve ever been to a large theme park or just a big venue you know how hard it can be to navigate back to a location. Amongst a maze of unnamed aisles or streets of vendors and endless lines of cars in parking lots it can be easy to get twisted around.

Luckily, the Maps app in iOS has you covered for these situations with a feature that allows you to mark any location and then get directions back to that point. It’s easy to use and provides several enhancements, but like many things in iOS, you might not be aware of these features from the beginning.

First, marking locations might be easier for you if you use the satellite view in Maps. If you’re in the standard Map view that shows just the street, tap the “i” button in the upper-right corner and you can get the satellite view. I discovered this feature by accident myself. OK, it wasn’t me, it was my 6 year old! Sometimes kids really are the best teachers.

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Once in the satellite view, position the map over the area you want to navigate to, and then pinch to zoom in. To mark the location, press and hold the exact spot. You can do the same thing in the regular Map view, so don’t feel like you have to be in the satellite view to do this. A pin will appear on the map at the marked location. On the iPad, a panel appears on the left side of the screen with controls and more options. With the iPhone these options appear at the bottom of the screen. From this panel:

**Get directions:** Tap directions to start navigating to the marked location. The button defaults to tell you how long a drive will be but you can easily switch to walking distances and other means of transportation. You can also tap the route summary to see more details and perhaps choose a different route if that option is available.

**Move the marker:** To reposition the marker slightly, tap edit location; for a more significant change in location press and hold on a new spot.

**Share the marker:** If you’re trying to explain to others how to get to you or your marked location, tap the share icon and then an app like messages or mail will appear so you can send the link to your directions.

**Delete the marker:** Simply tap on remove marker

**Make a favorite:** For a marked location that you might want to use repeatedly, tap add to favorites and give it a name. After that, you’ll be able to search for the location by name. Maps automatically syncs your favorites via your iCloud account. You can then access your location from another device at a later date if you want.

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As I mentioned in the beginning of my article I utilized many of these features on my recent vacation. I literally would have been lost without them! I have navigation built into my car, but found Apple Maps to be significantly more useful when driving as it provided me with multiple routes for most destinations and was fairly accurate for traffic issues and potential faster routes. I easily navigated back to our parked car when we left the theme park also easily located points of interest in our surrounding area. Living in a rural state I don’t always get to use all the features in my devices and apps. It was comforting to know thanks to my devices this country girl could make it in the hustle and bustle of busy cities!