The annual Orionid meteor shower will be at its best and brightest tonight (October 21-22) as the Earth passes through the stream of debris left behind by Halley's Comet, the parent comet of the Orionid shower. The event generally runs from October 2, picking up steam towards the middle of the month and fizzles out into November. Tonight stargazers can expect to see around 15 meteors an hour provided the sky is moonless. According to NASA the event is "considered to be one of the most beautiful showers of the year," with the Orionid meteors famed for their "brightness" and "speed."