There's no single, official scientific name for the cycle of night and day. However, here are some terms related to it:

* Diurnal cycle: This refers to the 24-hour period of time from one sunrise to the next.

* Earth's rotation: This is the fundamental cause of the night and day cycle. The Earth spins on its axis once every 24 hours, creating day on the side facing the sun and night on the side facing away.

* Solar day: This is the time it takes for the Sun to appear in the same position in the sky, which is about 24 hours.

While there's no specific "scientific name," these terms describe the phenomenon and its underlying causes.