Final answer:
The Earth orbits the sun once every 365.25 days, a period known as a year. This motion was originally misinterpreted as the sun moving around Earth, but we now understand that all planets in our solar system orbit the sun. Furthermore, the sun also moves, orbiting the center of the Milky Way in what's called a galactic year.
Step-by-step explanation:
The Earth orbits the sun once every 365.25 days. This period, commonly known as a year, is the basis for our calendar. However, it's not just Earth that orbits the sun. All planets in our solar system revolve around the sun in paths known as orbits, each taking a different amount of time. The time it takes for a planet to complete one full orbit around the sun is called a year on that planet.
Ancient astronomers initially believed that the sun moved around the Earth, due to its observed daily motion across the sky. However, we now understand that this is an effect of Earth's own rotation on its axis. Far from the Earth being the center of the universe, the Earth, like all planets in the solar system, orbits the sun.
It's also interesting to note that the sun itself moves, orbiting the center of our galaxy, the Milky Way. This larger orbit takes about 225 million years to complete, a timescale referred to as a 'galactic year'. In all of human history, we have experienced only a tiny fraction of a galactic year.
Learn more about Earth's Orbit