It’s commonly known that the Sun is the center of our solar system, with all the planets orbiting around it. However, this isn’t entirely accurate. In reality, the planets—and even the Sun itself—are orbiting a point known as the center of mass of the solar system.
A scientist has created an animation to show how the planets and even the Sun orbit this unseen center, helping us to understand a fascinating truth about our cosmic neighborhood.
The Barycenter
Dr. James O’Donoghue, a planetary scientist at the Japanese Aerospace Exploration Agency (JAXA), explains that everything in the solar system orbits this center of mass, or “barycenter,” including the Sun.
The planetary scientist shared captivating animations, based on data from NASA’s JPL Horizons system, in a Twitter thread to show how the planets and even the Sun move around this point of balance in the solar system.
In his animation, Dr. O’Donoghue shows how the Sun, Jupiter, and Saturn all orbit the barycenter. The barycenter is the point in space where the combined mass of two or more orbiting bodies balances out, and both bodies orbit around this center. (ref)
Although the Sun is at the center of our solar system, it only accounts for about 99.8% of the solar system’s total mass. This means that the Sun’s center doesn’t align exactly with the barycenter.
The barycenter of our solar system moves constantly, depending on where the planets are in their orbits. It can be near the center of the Sun or even outside its surface. As the Sun orbits this shifting point, it wobbles slightly.(ref)
In another tweet, Dr O’Donoghue explains, “The planets do orbit the Sun of course, we are just being pedantic about the situation. The natural thinking is that we orbit the Sun’s center, but that very rarely happens, i.e. it’s very rare for the solar system’s center of mass to align with the Sun’s center.” (ref)
Earth & the Moon Have Their Own Barycenter
Dr. O’Donoghue also released another animation demonstrating how the Earth and its Moon both orbit their shared barycenter. (ref)
When you think about Earth and the Moon, it’s not just the Moon orbiting Earth. They’re actually orbiting a point in between them. This point is a little bit closer to Earth than the Moon because Earth is more massive than the Moon.
So, while the Moon orbits around Earth, Earth is also “dancing” around the barycenter.
The Space Educator behind the Animations
Dr. James O’Donoghue, an ex-NASA scientist who published a study on Saturn’s rings, (ref) found himself in the spotlight in December 2018 when his mesmerizing animations about the solar system went viral.
His short and simple award-winning animations explained the physics of our solar system. Some of his best animations also include how the planets move and how slow light speed really is.
Thanks to his animations, it has changed the way we see the motion of our solar system and the planets.
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Nancy Maffia
Nancy received a bachelor’s in biology from Elmira College and a master’s degree in horticulture and communications from the University of Kentucky. Worked in plant taxonomy at the University of Florida and the L. H. Bailey Hortorium at Cornell University, and wrote and edited gardening books at Rodale Press in Emmaus, PA. Her interests are plant identification, gardening, hiking, and reading.
