Why The Solar System’s Planets Do Not Exactly Orbit The Sun

The general perception is that all the planets from our Solar System along with the asteroid belt are orbiting the Sun, at least putting it into a colloquial language. Einstein’s Theory of General Relativity is the one describing very well the motion of cosmic objects through space. But the truth is that they don’t actually orbit our host star.

Mercury, Venus, Earth, Mars, and all the other planets and asteroids are still revolving due to the tremendous gravity of the Sun. The difference is that they actually orbit the Solar System’s center of mass (aka barycenter), and even the Sun itself does so. We can define the barycenter as the point of an object at which it can be balanced perfectly, having all of its mass distributed even for all sides. James O’Donoghue, who is a planetary scientist at JAXA (Japan Aerospace Exploration Agency), made an animation for showcasing his claim a lot more clear:

The scientist explains:

It’s fair to say planets orbit the Sun, but that’s not 100% true. The Sun holds 99.8% of the Solar System’s mass, Jupiter contains most of what’s left (Saturn a distant 2nd), and in this vid you’ll see how Jupiter plays tug of war with the Sun. Everything orbits a center of mass!

Albert Einstein described gravity in a different way than Isaac Newton, the first scientist who tried to describe the well-known phenomenon. Instead of saying that objects exert a gravitational pull against others, Einstein brought a very different perspective: space itself actually pushes a smaller object like a car towards a bigger one like a planet. Massive objects can simply bend the fabric of space in the same way a heavy iron ball bends the canvas of a trampoline. Throw a tiny ball on the trampoline, and it will revolve around the larger iron ball. Throw it too close, and it will be dragged right aside the bigger ball. The planets are revolving around the Sun in the same way.

Understanding how gravity and other laws of physics were born is perhaps the ultimate challenge in science.

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Cristian Antonescu

About the Author: Cristian Antonescu

With a strong passion for astronomy since he was little and hundreds of articles written about this field, Cristian is a reliable writer who keeps the website up-to-date with news about the wonders of the Universe.

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