The first stargazers called anything that was lit up in the night sky a star. The word star comes from the Latin word “Stella” which means “to shine.” So the word star included planets, the moon, galaxies and what we call stars today.
Ancient peoples observed these objects and as time went by they noticed that some of the stars were “fixed in the sky” and some of them “wandered”. Years and years of watching these movements and recording them led to the creation of the calendar. Ancient peoples started to measure time by the objects they could see in the sky and where they were placed in the sky.
They used the stars in their daily lives in many ways. Navigation, future telling (astrology), seasonal changes, weather prediction, and telling time are just some of those ways. Life was intimately linked with the changes and patterns that occurred in the sky. At this time most astronomy was observed with the naked eye.
In the 1600s, the telescope was invented in the Netherlands using glass lenses. This allowed astronomy to develop into a modern science. People like Copernicus and Galileo studied astronomy at this time. The word, planet, or “wandering star” was first used during this time and included the moon and sun.
Then, Galileo discovered the four brightest moons of Jupiter using a telescope, proving that there are things in the Solar System that don't revolve around the Sun. The word moon was then extended to include satellites of other planets.
This was a time of great change in the minds of people concerning the Earth’s place in the universe. For about 1,400 years, people thought the Earth was the center of the universe. They also believed that the sun and all the other planets revolved around the Earth.
In the 16th century, Nicholas Copernicus had a different theory, he believed that the sun remained still in the center of the universe while all the planets revolved around it. This new theory was named the heliocentric system and is the most widely accepted today.
Modern day astronomers continue to build upon the observations and discoveries of ancient astronomers. And like any other scientific pursuit, as new data and evidence is found, ideas and terms are rethought and changed.