Where Is the Solar System

Barycenter is a term that is used to describe the mass center of 2 or more celestial bodies, i.e. stars and planets and/or a planet and moon(s). The solar system barycenter and Earth Moon system barycenter are described below.

Earth Doesn’t Actually Orbit the Sun?

You were taught that Earth and other planets in our solar system orbit the sun, and that our solar system orbits the center of the Milky Way. Did your science teacher have it wrong? Is everything you’ve learned about physics and gravity wrong? The Earth Doesn’t Actually Orbit The Sun? For all practical purposes, what you were taught wasn’t entirely wrong. Although the Earth does generally orbit the sun, in the strictest sense, it doesn’t. The sun and other planets each have their own gravity force which interacts and pulls on one another. The result of this phenomenon is that everything in an orbital system (like our solar system) orbits the center of mass of the system. This ‘center of mass’ of the solar system is called the solar system barycenter. The Earth, the sun and everything else in our solar system orbit this barycenter – not the sun .

Where Is the Solar System Barycenter?

The diagram displays the motion of the solar barycenter with respect to the center of the sun (shown as a yellow dotted line circle). A coordinate system (x-y axis = white lines) is centered at the center of the sun. The First Point of Aries (0 degrees celestial longitude) is at the far right of the horizontal axis. In a single star system like ours, most of the time (but not always), the solar barycenter is located somewhere within the star (in our case, the sun) itself. However, most barycenters continuously change as massive objects (like planets) orbit a star. If an unusual alignment happens where a large percentage of mass is on one side of the star, the barycenter can exist outside of the star’s radius. In cases of 2 star systems, the barycenter will be located between the two stars. If the stars aren’t of the same mass, the barycenter will be closer to the heavier, or more massive one. So the solar system barycenter and the sun's location are dependent on the motion of the planets and other massive objects in the solar system. If you want all the gory detailed data re: the position down to the .00000001 of a degree longitude, you can go here .

Where Is the Earth Moon System Barycenter?

Given the above information regarding the solar system barycenter, it follows that the Moon doesn’t revolve around the mass center of the Earth; it revolves around the Earth Moon System barycenter. The Earth Moon System barycenter is on the axis between the center of masses of the Earth and Moon. The Moon is ~ 1/82 of the mass of the Earth so this barycenter is about 3000 miles/4800km from the center of the Earth along the axis between them (average Earth Moon distance 240,000miles/380,000km). The barycenter of the Earth Moon System is always within the Earth. The distance to the Moon also varies by about 30,000 miles, or 50,000 km, therefore the location of this barycenter within the earth will vary about 380 miles or 600 km from a point 3000 miles or 4800 km within the Earth, during one revolution of the Moon in 29 days. The barycenter and another point, the anti-barycenter (equal distance from the center of the Earth along the Earth Moon axis in the opposite direction to the barycenter), are two points at which 4 of the Iasoberg bands (2 bands per point) are focused.