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Radio waves are light waves because they’re made up of photons, little particles of energy that vibrate along the electric and magnetic fields. If our eyes could perceive radio waves, looking up at the night sky would reveal a world of colors that are otherwise invisible to us, and communications towers would emit rainbow-colored waves into the atmosphere.
That said, when people say, “light waves,” they might be referring to visible light, the only part of the electromagnetic spectrum that is visible to the naked eye. Sometimes, infrared and ultraviolet, which are not visible to us, are included. Along with Infrared, visible light, ultraviolet, x-rays, gamma rays, and microwaves, radio waves are better referred to as electromagnetic radiation.
It’s easy to think that radio waves travel at the speed of sound. After all, most of us immediately associate the word, radio, with listening to music or the news. But radio waves are light waves, and therefore, they travel at lightspeed. In the vacuum of space, light travels at approximately 186,282 miles per second. That’s almost the distance that a modern vehicle covers over its entire lifetime!
In space, radio waves will keep traveling infinitely. In fact, early radio signals from Earth have already traveled 303 trillion kilometers through space, way past our nearest neighboring star. On Earth, scientists use giant radio telescopes to listen for signals from distant galaxies. But the further radio (or any other light) travels, the more it will dissipate and become weaker.
One of the most extraordinary radio signals to have ever been recorded is the Wow! signal. The mysterious signal detected in 1977 appeared to have come from Sagittarius. Some people believe the Wow! signal may have come from an extra-terrestrial intelligent civilization, while others believe it had a more natural source—astronomers are still undecided!
On Earth, radio waves will travel for a long distance before they dissipate and become weaker. In long-distance communication, High Frequency (HF, or skywave) signals can be directed towards the ionosphere, where the radio waves will bounce back down towards their intended destinations.
WiFi uses high-energy radio waves to transmit data—which, on the electromagnetic spectrum, are referred to as microwaves. Bluetooth devices also transmit data along the same low-power microwave range.
In fact, radio and microwaves are used by humans extensively throughout our lives. We use radio or microwave for watching television, connecting to the internet, making telephone calls, sending text messages, radio astronomy, and navigation. Meanwhile, we also use microwaves in medical settings for cancer treatment, and at home for cooking and preparing meals.
Radio waves are a type of electromagnetic radiation. They have the longest wavelengths, the lowest energy, and the lowest frequency on the electromagnetic spectrum. Radio waves are light, but they are not visible to human eyes. On Earth, we are surrounded by radio waves. While some are naturally occurring, others are man-made.
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Cheryl is a freelance content and copywriter from the United Kingdom. Her interests include hiking and amateur astronomy but focuses her writing on gardening and photography. If she isn't writing she can be found curled up with a coffee and her pet cat.
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