We're thrilled to announce the launch of our newest course: Solar Physics. Spanning 16 comprehensive chapters, this course takes you from the thermonuclear reactions at the Sun's core all the way to the space-weather events that disrupt satellites, power grids, and radio communications on Earth.
What Makes This Course Unique?
Most introductory solar physics materials skim over the quantitative derivations that give the subject its predictive power. Our course does the opposite — every key result is derived from first principles with all intermediate steps shown. Whether you're a graduate student preparing for qualifying exams or a working physicist brushing up on heliophysics, you'll find the level of detail you need.
16 Chapters: A Guided Tour
The course opens with Chapter 1: The Solar Interior, where we derive the equations of stellar structure — hydrostatic equilibrium, radiative transfer, and the temperature gradient — and apply them to a standard solar model. We introduce the Gamow peak calculation, showing exactly why the pp-chain dominates at solar-core temperatures of roughly 15 million kelvin and how tunnel probabilities and Maxwell-Boltzmann tails combine to set the fusion rate.
Chapters 2–4 cover helioseismology and the solar atmosphere. You'll learn how acoustic p-modes and gravity g-modes reveal the internal rotation profile, the tachocline shear layer, and even the helium abundance in the convection zone. The chromosphere and corona chapters explain the temperature inversion problem and survey current heating models — from Alfvén wave dissipation to nanoflare statistics.
Chapters 5–8 form the magnetohydrodynamic core of the course. We derive the MHD induction equation, classify magnetic field topologies (potential, force-free, and non-force-free), and work through the Sweet–Parker reconnection model step by step. The derivation shows why the classical reconnection rate scales as the inverse square root of the Lundquist number — and why that rate is far too slow to explain observed flare timescales. We then introduce Petschek reconnection and plasmoid instability as faster alternatives.
Chapter 9: The Parker Solar Wind is one of the highlights. Starting from Parker's 1958 isothermal wind equation, we show the critical-point analysis that yields the unique transonic solution. We extend the model to include polytropic indices, magnetic field effects, and wave-driven acceleration, reproducing the bimodal fast/slow wind structure observed by Ulysses and Parker Solar Probe.
Chapters 10–12 address solar flares, coronal mass ejections (CMEs), and solar energetic particles (SEPs). The flare chapter derives the CSHKP standard model geometry, estimates magnetic energy budgets, and explains the Neupert effect linking hard X-ray and soft X-ray light curves. The CME chapter covers flux-rope models, the torus instability criterion, and interplanetary propagation using the drag-based model.
Chapters 13–14 turn to the solar dynamo. We present the mean-field αΩ dynamo equations, the Babcock–Leighton mechanism for poloidal field regeneration, and flux-transport dynamo models that reproduce the 11-year activity cycle. The chapter on solar-cycle prediction compares precursor methods, spectral techniques, and machine-learning approaches.
Chapters 15–16 close the course with space weather and instrumentation. You'll learn the Dst index derivation, geomagnetic storm classification, and the physics of geomagnetically induced currents (GICs). The instrumentation chapter surveys coronagraphs, magnetographs, EUV imagers, and in-situ particle detectors aboard missions from SOHO to Parker Solar Probe.
Stanford PHYS780 Lecture Notes
Throughout the course, we reference and link to the Stanford PHYS780 graduate lecture PDFs, which provide additional worked examples, observational data tables, and problem sets. These notes complement our derivations and give you a second perspective on the material — invaluable for building deep understanding.
Inline SVG Diagrams
Every chapter includes inline SVG diagrams rendered directly in the browser — no external image hosting, no slow loads. You'll find magnetic field line topologies, reconnection geometries, wave dispersion curves, and solar-wind velocity profiles all drawn with precise coordinates and labeled axes. These diagrams are resolution-independent and look sharp on any screen.
Who Is This Course For?
The course targets advanced undergraduates and graduate students in physics, astronomy, or space science. It assumes familiarity with electromagnetism at the Griffiths level and basic fluid mechanics. No prior knowledge of solar physics is required — we build everything from the ground up.
Start Learning Today
The full course is available now, completely free, with no registration required. Dive in and explore the physics of our nearest star.