If I majored in physics, what job opportunities would be available to me?

I think it is great that you want to major in physics. It was one of my favorite classes in college. Many of my friends who studied physics work in the the space field. Some people fly satellites, design space vehicles, teach, and design experiments to explore space. You are very lucky, your generation will probably land the first people on Mars. There are some who are using concepts in physics to understand areas of chemistry, biology and other sciences. Consider an internship with government agencies like the Dept of Energy, Dept of Defense, or NASA when you are a senior in HS or in college. Energy development is also important. That is another area you can pursue. I wish you the best of luck. Please pursue your dreams.

More generally, physics is an outstanding foundation for any number of STEM fields. The mathematical, analytical, and experimental skills you'll pick up in your courses and (probably) internships will prepare you for a huge number of potential careers, not just those traditionally associated with physics. Besides aerospace (usually associated with spacecraft, frequently manned), there are huge vistas of astrophysics (cosmology, exoplanets, stellar astronomy, gravitational-wave astronomy, neutrino astronomy, etc., etc.); biophysics, physical chemistry, materials science, nanomaterials, superconductors, superfluids, and all of their applications (batteries, Hyperloop, hydrophobic coatings, protein-folding, designer proteins/drugs, robots/nanobots/biobots, etc.); associated engineering fields (aeronautical/aerospace engineering, mechanical engineering, chemical/biochemical engineering, etc.); and, of course, all things computational, which is where I ended up (simulation, data analysis, data-mining, graphics, physics-inspired algorithms, compression, quantum computing, distributed computing, etc.).

I would second Marla's advice to look into internships at government and corporate labs--I worked at Fermilab, Argonne, and Bell Labs over three summers (both undergrad and grad) and got a three-year fellowship at NASA Ames to simulate galaxy evolution in grad school. But there are close to a dozen other NASA centers alone, plus SLAC, LBL, LLNL, BNL, Sandia, ORNL, and I'm sure at least half a dozen others operated by the DoE, plus university projects and collaborations like the U of Minn's neutrino and proton-decay experiments in the Soudan mine, the Minos(sp?) collaboration, various observatories throughout the Americas, Hawaii, and Antarctica, etc. Your local physics department should be able to quadruple that list easily.