For the next several years, the sun is not the center of the solar system
Updated: Feb 18, 2019
While the sun contains most of the mass of the solar system and is the approximate center, the actual center of the solar system is not always located within the sun itself. While the planets contain very little mass relative to the sun, the distance between the sun and the larger gas giants gives those planets a more significant moment arm than might first be expected. Jupiter, in particular, shifts the center of mass in the solar system to a point generally outside the surface of the sun, with the other planets either adding to or taking away from the center of mass shift.
The images above and below help to illustrate that even though Jupiter has far less mass than the sun because it orbits far from the sun, it can balance the mass of the sun at a point located just beyond the sun's surface.
So, while the conceptual model of the solar system is often one where the sun is sitting in place and all the planets orbiting around it, the reality is that the planets AND the sun are all revolving around the center of mass of the solar system like the animation below shows.
While Jupiter is the main planetary body that influences the center of mass of the sun, at times the other gas giants like Saturn, Uranus, and Neptune line up on the same side of the sun as Jupiter. Saturn is currently close to the same location as Jupiter is in its orbit, and in the coming years, both will be shifting into the same quadrant as Uranus and Neptune. The result is that most of the mass of the planets in the solar system will all be on the same side, thus shifting the center of mass of the solar system farther away from the sun than usual. The following two plots show the orbital positions of the gas giants in late 2018 and again in mid-2023.
However, by 2030, Jupiter will have swung around to the opposite side of the solar system relative to Saturn, Uranus, and Neptune, mostly balancing those planets, and the center of mass of the solar system will once again be near the center of the sun.
So, as the plot below shows, the center of mass of the solar system, and the point that all the planets and the sun orbit around will be farther from the center of the sun in the coming years than at any time during the next few decades.