Final answer:
There are 88 official constellations that divide the celestial sphere, similar to how borders divide a country into states. These regions have boundaries that run north-south and east-west, and differ in size.
Step-by-step explanation:
The sky as observed from Earth is divided into 88 official constellations. These are essentially regions of the celestial sphere used to organize the sky into manageable sections, much like dividing a country into states. The modern boundaries between the constellations are set along imaginary lines that run north-south and east-west, ensuring that every point in the night sky can be associated with a specific constellation. These constellations vary in size, just as states do in their land area. An asterism is a recognizable pattern of stars within a constellation, or spanning across multiple ones, like the Big Dipper within Ursa Major.