Final answer:
The appearance of the moon as stationary at night is due to its slow angular velocity and our perspective, making its motion difficult to perceive in real-time.
Step-by-step explanation:
When you see the moon at night and it appears to be not moving, it is due to its relatively slow angular velocity, but it's primarily a matter of perspective. The moon does move across the sky but at a speed that is difficult to perceive in real time. The actual movement is barely noticeable without reference points and over a short period.
The moon orbits the Earth once every approximately 27.3 days—referred to as the sidereal month. This is its orbital period, during which it travels a full 360 degrees around the Earth. However, due to this slow motion and the vast distance between the Earth and the moon, we do not readily observe the moon's movement in the night sky without patiently watching it for a considerable amount of time or using time-lapse photography.