[dylan604]

Not really sure why this was killed, but it's absolutely true. From the moment we started making radio signals, we've been broadcasting our location. Every single time we communicate with our deep space probes, we're sending out very specific signals that we're here. To that end, that's the entire point of the opening scene in the movie Contact. It's just that the time frame we've been broadcasting is just a drop in the ocean of cosmological time, and the signals really haven't gone very far in comparison.

[samus]

Our signals are so weak that they will probably fade and get drowned out by the electromagnetic noise of interstellar space. We can communicate with our probes only because we use directional signals and we pretty much know what to look for on the receiving end. If aliens manage to pick those up, then their probes would already be like < 1ly away, and they would have noticed us long ago by different means.

The intentional signals are a different story though.

[exe34]

They can probably just watch co2 spectral lines and count how many of us there are.

[qbrass]

Just as many as on Mars, but hardly any compared to Venus.