A sphere of electromagnetic radiation now stretches about 240 light‑years across, expanding at light speed since the first powerful broadcasts of the 1900s. It contains every radio song, TV show, radar ping and deliberate transmission ever sent into space. Any extraterrestrial civilization with a sufficiently sensitive receiver inside that sphere would already have heard Earth’s chatter, though the signal now fades into background noise.

Each milestone creates a concentric shell. Signals that broke through the ionosphere in the 1930s form the outer ring, while the 1936 Berlin Olympics broadcast has traveled about 90 light‑years, now passing Vela’s stars. The most deliberate beacon, the Arecibo Message sent in 1974, has reached roughly 52 light‑years toward the M13 cluster, a sliver of its intended 25,000‑light‑year journey.

Because the bubble covers only about 0.000002 % of the Milky Way, most stars remain oblivious to our presence. Thousands of nearby systems—Proxima Centauri, Alpha Centauri, Barnard’s Star—lie within the sphere, but any reply would take centuries to arrive. Earth’s radio bubble therefore remains a still faint, ever‑diluting imprint of our early technological voice in the cosmos.