Not many people know about constellations even though they are all around us. Constellations are conspicuous groupings of stars that look like objects and figures in the sky. Astronomers use constellations to assist them in locating artificial satellites and finding specific stars.
Phaenomena (c. 300-240 BC) by Eudoxus of Cnidus contains examples of some of the earliest defined constellations. Some Greek work has been lost to time but is still important. A poet named Aratus made a versification of Phaenomena and Hipparchus; a philosopher made a commentary about it. Three hundred years later, the astronomer Ptolemy wrote the Almagest (c. 150 AD), a catalog that contains his “Uranometria.” The “Uranometria” has a list of the names and orientations of 48 constellations. This is considered the modern version. 40 out of the 48 constellations are still used today.
Constellations such as Orion, the Big Dipper, and Cassiopeia are easier to find because they are brighter than the majority of constellations. But some of the constellations only appear for a short amount of time each year. They are located in the “zodiac” which is an area that is divided into 12 signs. Each sign contains a constellation, like Capricornus and Virgo. These are called zodiac signs. When the sign is visible depends on where it’s located.
As time goes by, with more people interested in astrology, the number of constellations has risen from 40 to 88. Some of the newer constellations are “Vulpeca,” “Pyxis,” and “Columba.” You can find out more about constellation at the International Astronomical Union website: https://www.iau.org.