Where is the Solar System's Barycentre this year?

Ever since the Copernican Revolution, we have known that the Sun is the centre of the Solar System. Orbits of the planets don't need to be circular (in fact, Mars' orbit is quite oval), but the one thing that's correct is that the sun is at the centre.


Well, not quite.

Moving to a heliocentric view of the Solar System was a step forward, but it's more accurate to say that everything in our solar system, including the Sun, orbits the centre of gravity of the whole system.

Time for a thought experiment.

Imagine you've got a dinner plate, with some items on it. There's a large burger in the middle, a pile of chips on one side, and a restrained amount of salad on the other side (we wouldn't want to overeat, would we?).

Now imagine you want to balance the plate on your finger, circus-style. If you don't want to drop your food on the floor, you're going to have to choose very carefully where your finger goes.

If you balance the plate with your finger right underneath the burger, it's going to tip over, because the reasonably heavy chips on the side of the plate will overbalance it. You're going to have to move your balancing finger towards the chips a little. You'll probably also have to consider the salad, although that's pretty light and won't mean much of a correction.

But eventually you'll get your plate balanced.

This balance point is called the "barycentre", or the centre of gravity  of the whole system. It's dominated by the position of the heaviest object, but offset by all the others in the system as well, depending on how heavy they are and where they are.

Notice that the barycentre doesn't need to be under any of the food? It might be part way between the burger and the chips.

This is what happens with our solar system as well. When Jupiter and the other planets are mostly one side of the Sun, the barycentre can actually be outside of the sun. As the planets move around in their orbits, the barycentre moves around in response.

The image I've attached shows how it has moved over the past few decades.

Incidentally, I heard this about this graphic on a podcast I listen to, Dear Hank and John. The itslef image came from Wikipedia, and I had a hard time tracking it from there - Wikipedia's crediting link seemed to go nowhere. The graphic seems to be all over the Internet, and it's hard to know where its actual origin is.