This "astronomy makes no predictions" meme is goofy. Halley got a comet named after him by predicting the year of its return. That was a completely falsifiable hypothesis. If you like something a bit more current, there are plenty of falsifiable hypotheses concerning e.g. neutrino mass that various underground/under-ice detectors will test in the next few years.

Such hypotheses are not inherently impossible for climate science.

(Shrug) Nobody is asking us to shut down air travel and stop eating steak because of an anthropogenic increase in the cosmic microwave background.

Good to know your opinion of the scientific method depends on the political implications of its conclusions.

"Extraordinary claims require extraordinary proof." - Carl Sagan

"No, extraordinary claims don't require more proof than any others, but extraordinary demands do." - Me