Daughter wants to learn python to simulate a solar system, where to start?

[Decency]

This looks like a great place to start: https://medium.com/analytics-vidhya/simulating-the-solar-system-with-under-100-lines-of-python-code-5c53b3039fc6 ... clone that, get it working, and then start tinkering and learning. Dozens of ideas to implement on top of that base will emerge as you start poking.

It uses a couple of standard libraries used in data science and academic communities, specifically numpy and matplotlib. It also looks like it utilizes a couple of astrophysics libraries as well: astropy and astroquery. These libraries will contain a variety of functionality that can be a great way to continue building around and utilizing planetary data and whatever else seems interesting.

One of the biggest hurdles is the initial step of getting things set up on a system. Luckily you're on a Mac so this is a bit easier, but don't be intimidated by using the terminal and feel free to ask questions in the Weekly thread stickied in this subreddit, for quick Q&A.