“Founded in 2002 by Nobel Laureate Carl Wieman, the PhET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations. PhET sims are based on extensive education research and engage students through an intuitive, game-like environment where students learn through exploration and discovery.”
Hyperphysics is an extensive resource for many subfields of physics. Topics usually include a brief introduction and thorough description, the basic relevant formulas, and links to related topics.
Try to make your own solar system with Earth-sized planets, ice giants, gas giants, and more! Make sure there aren’t any gravitational resonances which throw your planets out of orbit!