Today, there are 88 official constellations. But this rule is only about 100 years old. Before that, different countries used different star pictures.

For example, in China, people saw the emperor's palace in the stars. In South America, the Inca saw animals in the dark parts of the Milky Way. A study of 56 cultures found that people often connected the same stars in different ways.

Most of us learn that there are 88 constellations, but this list became a worldwide rule only in 1922, when the International Astronomical Union decided on it. Later, official boundaries were drawn, so today a constellation is really an area of the sky, like an address, rather than just a picture. Patterns such as the Big Dipper are not official constellations. They are called asterisms.

Around half of the 88 come from ancient Greece, while many in the southern sky were added later by Europeans and named after tools like the telescope. Other cultures created completely different star pictures. In 2022, a researcher compared 1,802 constellations from 56 cultures and found that the same stars were often connected in very different ways.

Although schoolchildren learn that the sky contains 88 constellations, that number is a relatively recent convention. By the nineteenth century, competing star atlases listed more than 100, so in 1922 the International Astronomical Union adopted an official list at its first General Assembly in Rome. The Belgian astronomer Delporte drew precise boundaries, approved in 1928 and published in 1930.

Modern constellations are therefore regions of the sky that function like addresses, rather than pictures formed by joining stars. Their origins are mixed: about half trace back to the 48 constellations recorded by Ptolemy in the second century, while many southern ones, named after instruments such as the telescope and microscope, were added after Europeans began exploring the Southern Hemisphere. Other traditions read the sky very differently.

Chinese astronomy mapped an imperial court onto small star groups, and the Inca identified animals in the dark patches of the Milky Way. In 2022, a network analysis of 1,802 constellation drawings from 56 cultures found recurring design types, yet strong agreement across cultures appeared only in a few sky regions, such as Scorpius with its chain of bright stars. Because the drawings came largely from digitized software collections, the dataset may contain biases.