Re: Why are the axes of the planets at different angles?

Well, this is a good question. The absolute truth of it is that no one knows for sure why the axes of the planets are why they are. This is because no one was around when the solar system was forming to watch the process.

But here is a popular theory that is based on a lot of scientific investigation:

Many people believe that our solar system began as an unbelievably giant blob of hot matter that might have been thrown out of the explosion of a previous giant star or something.

So here was have this big blob of hot matter thats spinning and churning around. As the matter cools, tight swirls of churning liquid matter begin to clump up into smaller blobs that are also spinning too. Now the big blob has a certain angular momentum.... the tendency to stay spinning in a certain direction. As it starts to break up into smaller spinning blobs, the TOTAL angular momentum of all of the blobs is still the same as the one big blob, even though each individual blob may be spinning differently than another.

This little blobs cool to become planets and other bits of solar system stuff. Early on, they are all over the place, orbiting wildly around the center burning blob (the Sun), smashing into each other, flying away from the Sun, falling into the Sun. And at the same time, other objects from outside the system come flying in and get caught in the gravity of the solar system.

After a billion years or so, things settle down. The complex combination of spinning objects and gravity make it more comfortable (more stable) for objects to orbit around in one direction and in about the same flat plane. Some things are a little tilted, some move in the reverse direction, but for the most part it's easier for planets and other objects to move like they do.

Any planet that is spinning a certain way, began its life spinning in that direction, either because the blob of matter it came from was just spinning like that when it started, or maybe, early on, some stray giant rock from somewhere else passed by and pushed it to spin in that direction.

The solar system is very very old and a lot of things have happened to it since it was formed. We can only use our knowledge of physics and other sciences to make educated guesses about how things might have been and how they got where they are. Questions like yours help inspire us to learn more about the universe, and better appreciate its complexity.

Maybe someday, you will get to see some new solar system being developed, and then you'll know better than anyone how the planets spin the way they do.

Thanks for your question!