A Friend wrote in rec.arts.tv:

In article , Ed
Stasiak wrote:

Interesting pic, showing what tv programs are just now reaching other planets,
up to 70 light years from Earth when the first tv signals were broadcast;

https://blogs-images.forbes.com/star...Ui5TtZZIh7e1wH
61e26RoA.jpg?width=960

All our signals descend into general background noise within a
lightyear and a half. They can't and won't be detected unless
somebody travels pretty damn close to us and is listening carefully for
them.

Is that according to only 1970s or 80s research.