Approximately 4.6 billion years ago, the solar system originated as the sun emerged from a dust cloud remnants of previous stellar explosions. The birth of the giant planets—Jupiter, Saturn, Uranus, and Neptune—occurred around 4.59 billion years ago. Subsequently, around 4.5 billion years ago, the formation of the smaller, rocky planets—Mercury, Venus, Earth, and Mars—took place, as reported by The Planetary Society.

Nevertheless, during the initial stages of planetary formation, the orbits of the planets around the sun differed from their present configurations, particularly in the case of the giant planets. Approximately 100 million years after the initial planet formation, a period of “dynamical instability” ensued. This instability led to a gravitational struggle among the massive celestial bodies, resulting in the expulsion of outer solar system planetary material and even some emerging protoplanets from the solar system, as explained by Sean Raymond, an astronomer at the Bordeaux Astrophysics Laboratory in France and an expert on planetary systems, in correspondence with Live Science.

Once the planets had emerged and completed their positional adjustments through interactions, they eventually settled into consistent and stable orbits. These orbits have remained largely unchanged for about 98% to 99% of the solar system’s existence, according to Raymond. Consequently, the current orbital dynamics of the planets provide a reliable basis for estimating the number of revolutions they have completed around the sun.

For instance, Earth, taking a year to orbit the sun, has been in existence for approximately 4.5 billion years, suggesting it has completed roughly 4.5 billion orbits around the solar system. However, the total number of orbits varies significantly among other planets due to the differing lengths of their years compared to Earth’s.