April / May (Usually visible from northern latitudes)
Notes
The Messier Number 'M51' is sometimes used to refer to both the Whirlpool Galaxy and its companion NGC 5195. In that case, the Whirlpool itself is identified as 'M51a'.
The Whirlpool Galaxy is not far from the Northern Galactic Pole in the sky, meaning that it is far 'above' the plane of our own Galaxy. The Whirlpool itself is much too far away to show on this diagram.