# Earth’s Radio Bubble: How Far Do Our Signals Travel?
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what is Earth’s radio bubble?
The first intentional radio broadcast is credited to reginald Aubrey Fessenden on December 24, 1906.Fessenden transmitted voice and music (a short speech, a violin performance of O Holy Night, and a Bible reading). Prior to this, radio signals were mostly Morse code. This was the first known broadcast meant to be heard by a general audience as sound. And it’s said that ship radio operators in the Atlantic, who heard it, were astonished to hear music and speech over their receivers!
And now, more than a century later, the radio waves that transmitted Fessenden’s broadcast – and many more radio waves since then – are still traveling outward into our Milky Way galaxy.But just how far have our radio waves reached? Radio waves are part of the electromagnetic spectrum, so they travel at the speed of light. And it’s been 119 years as that first radio broadcast.
So the radius of Earth’s radio bubble is 119 light-years, or a sphere with a diameter of 238 light-years across.
What is the extent of Earth’s radio bubble?
So the strains of Fessenden’s violin are still traveling through space, leading the way in Earth’s ever-expanding radio bubble. The distance of 238 light-years might sound like a lot, but it is indeed just a tiny dot within the Milky Way galaxy. Our galaxy extends some 100,000 light-years across. So it would take fesssenden’s message approximately 23,000 years to reach the galaxy’s nearest outer edge. And it would take his message about, say, 27,000 years – going in the opposite direction – to reach the galaxy’s center and maybe about 77,000 years for it to reach the far side of the galaxy.
So you might say that Earth’s radio bubble – with Fessenden’s 1906 broadcast on its leading edge – will take roughly 77,000 years to cross the entire Milky Way. One caveat, though. The “radio bubble” i