As we know from elementary school, Jupiter is a gas giant and the fifth planet in the solar system, besides it is huge. However, Jupiter is so huge, that it doesn't really orbit around the Sun. At least not exactly. With 2.5 times the mass of all other planets in the solar system combined, it is large enough to make the center of gravity between Jupiter and the Sun not inside the Sun, but at a point in space just above the theoretical surface of the sun, and I say theoretical because this gas ball, with a diameter of 1.4 million kilometers, is held together by gravity alone. This means that the Sun does not have a firm surface, nevertheless, the Sun appears to us as a shining sphere with a sharp edge, what it is called the visible surface of the Sun or the photosphere. The photosphere, is the layer below which the Sun becomes opaque to visible light. Photons produced in this layer escape the Sun through the transparent solar atmosphere above it and become solar radiation, or sunlight.
Usually, when a small object orbits a large object in space, the body with less mass does not actually travel in a perfect circle around the larger one. Rather, the two objects orbit a combined center of gravity. In situations we are familiar with (such as the Earth orbiting the much bigger Sun) the center of gravity resides so close to the center of the larger object that the impact of this phenomenon is negligible. The largest object seems not to move, and the smallest draws a circle around it.
But reality is always more complicated. For example, when the Moon orbits Earth, Earth and its satellite orbit a combined center of gravity. But that center of gravity is so close to the center of the Earth that the movement of the planet around the point is impossible to detect, and the Moon follows an almost perfect circle around the entire planet.
The same happens when most of the planets orbit the Sun. The mass of the star is bigger than Earth, Venus, Mercury, Saturn, so much so that the center of gravity of all of them is deep within the star itself . That does not happen with Jupiter. The gas giant is so big that its center of mass together with the Sun, or barycenter, is actually 1.07 solar radius from the center of the Sun (or 7% radius above the Sun's surface). Both the Sun and Jupiter orbit around that point in space.
Josher
February 9, 2019
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