Is the sun directly in the center of earth's orbit?
The orbit is an ellipse of small eccentricity e = 0.01671. Sun is at a focus of the ellipse The distance of the Sun from the geometrical center of the orbit is 2,499,787 km
The semi-major axis of the ellipse a = 149598262 km. The Sun-center distance is ae = 2499787 km.
Technically the Earth doesn't orbit around the Sun and the Moon doesn't orbit around the Earth.
The Earth and the Moon both orbit around the centre of mass of the Earth and Moon. This is called the Earth-Moon Barycentre or EMB. It is about
In a similar way the Sun and all of the planets and other bodies in the Solar System orbit about the centre of mass of the Solar System. This is called the Solar Centre Barycentre.
The location of this barycentre is constantly changing due to the relative positions of the planets. It is usually just below the Sun's surface and sometimes even above the Sun's surface. It's position can be anywhere from close to the centre of the Sun to over
The graph shows the position of the Solar System Barycentre relative to the centre of the Sun from 1938 to 2051. The unit of distance is the solar radius
So, the true story is that both the Sun and the Earth-Moon Barycentre orbit around the Solar System Barycentre.
Also, the Earth's orbit is slightly elliptical, with the Earth orbiting around one of the foci. The orbit is not a true ellipse as it is constantly being deformed by the gravitational pull of the other planets.
The Earth's perihelion distance
So, the distance of the Sun from the centre of the Earth's orbit is