In theory, an advanced extraterrestrial civilization could potentially detect signs of life on Earth. Here are a few ways they might do so:

It’s important to note that while these are plausible methods an advanced extraterrestrial civilization could use to detect us, it also assumes they have developed technology at least as advanced as our own and that they’re actively looking for signs of life in the universe. Additionally, the scale of the universe is incredibly vast. Even at the speed of light, signals from Earth have only reached a very small portion of our galaxy.

Electromagnetic Signals

Atmospheric Composition

Light Pollution

Technosignatures

Transit Method