BLADE: TRINITY (2004) 5:30 p.m. on Syfy. Mahershala Ali might have just been announced as the star of a new version of Blade, but for now Wesley Snipes is still the human face of this comic-based series. He stars here as the titular martial-arts-toting vampire hunter, in what proved to be the conclusion of a trilogy. The previous two installments will air on Syfy directly before, at 12:30 p.m. and 3 p.m.

ANCIENT SKIES 8 p.m. on PBS (check local listings). This three-part documentary series explores the evolution of humans’ relationship with the celestial. The first episode, “Gods and Monsters,” looks at the way the night sky informed religions.