Which informal fallacy is committed in the following argument: Scientists have been trying for centuries to disprove the claims of astrology and none of them has ever succeeded; therefore, we must conclude that astrology's claims are true?

Treating astrology's claims as true merely because no one disproved them is an appeal to ignorance.

Argumentum ad ignorantiam infers a proposition true from the absence of proof against it.

Failure to disprove a claim is not positive evidence for its truth.

The lack of a successful refutation leaves the claim unproven, not established.

This shifts the burden of proof onto the absence of counter-evidence.