This cartoon is an example of the informal logical fallacy of false cause (non causa pro causa - when something is erroneously posited to be the cause of something else, but in reality the conclusion is not dependent on the observed temporal relationship between the imagined cause and its effect; lit., "not the cause for the cause").
Since the final exam for my Logic course is a week from today I'm posting this as a warning to my students that this kind of argument won't work for two reasons: a) the informal fallacy it commits; and 2) astrological signs have no causal efficacy.