Radio waves from Earth have been moving through space for more than a century. They did not start as part of any grand plan to reach the stars. They began quietly, as a new way for humans to speak across oceans. Since then, those signals have continued outward, spreading slowly into space at the speed of light. Scientists sometimes call this expanding region Earth’s radio bubble. It is not something you can see or touch. It is simply the growing reach of our earliest broadcasts. As time passes, the bubble grows larger, thinner, and harder to detect. Still, it raises a simple question. How far have our voices really gone?
How did Earth start sending radio signals
The story begins in 1906 with Reginald Aubrey Fessenden. On December 24 that year, he made the first known radio broadcast meant for a general audience. Instead of Morse code, listeners heard music and spoken words. He played a violin and read from the Bible. Ship operators at sea picked up the signal, not fully realising they were hearing the beginning of something much larger.That broadcast did not stop when the sound faded. The radio waves continued moving outward, leaving Earth behind. Over time, countless other signals followed. Together, they formed the earliest layers of Earth’s radio bubble.
What exactly is Earth’s radio bubble
Earth’s radio bubble is the region of space reached by radio waves emitted from Earth. Because radio waves travel at the speed of light, the size of the bubble depends on how long we have been transmitting. After 119 years, the bubble has a radius of about 119 light years.This does not mean the signals are strong or clear. The bubble is more like a thinning shell. As the waves spread out, they weaken and blend into background noise. There is no solid edge. Just distance, time, and fading energy.
How small is the radio bubble compared to the galaxy
When placed against the Milky Way, Earth’s radio bubble is very small. The galaxy stretches roughly 100,000 light years across. Our signals have barely moved beyond our local neighbourhood.If Fessenden’s original broadcast could survive unchanged, it would still need tens of thousands of years to cross the galaxy. That scale helps explain why space often feels silent. Distance matters more than we imagine.
Which stars have our signals already reached
Some nearby stars now sit inside Earth’s radio bubble. Proxima Centauri, just over four light years away, has already been passed by our earliest broadcasts. Many other stars within 119 light years have also been reached.A study by scientists at Cornell University identified 75 star systems that not only lie within this range but could also observe Earth passing in front of the Sun. In theory, these systems have both received our signals and could notice our planet.Still, receiving does not mean understanding. By the time the signals arrive, they are extremely weak.
Could anyone actually hear our broadcasts
In practical terms, no. The radio waves fade quickly as they spread out. By the time they reach distant stars, they are lost among natural cosmic noise. Even an advanced civilisation would struggle to separate a human broadcast from the background of space.At best, the signals might hint that technology exists somewhere. They would not carry music, voices, or meaning in any clear way.
Are Earth’s radio signals getting weaker over time
Yes. Early radio and television broadcasts leaked large amounts of energy into space. Modern communication does not. Fibre optics, cables, and digital systems keep signals closer to Earth.This means the radio bubble continues to expand, but newer layers are thinner than the older ones. In time, Earth may become quieter to the rest of the galaxy, not louder.
What does Earth’s radio bubble really tell us
The radio bubble is less about contact and more about perspective. It shows how young our technological presence is and how vast space remains. Our signals are travelling, but slowly, faintly, and without direction.They may never be noticed. Or they may simply exist as a brief trace of a planet learning how to speak.
