Interactive Demos
Explore astronomy concepts through interactive visualizations
These interactive demos let you explore fundamental astronomy concepts hands-on. Each demo works on phones, tablets, and computers.
Earth & Sky
Seasons
Why does axial tilt — not distance from the Sun — cause seasons? Explore with different planets and watch a year unfold.
Open Demo →seasons axial tilt day length
Moon Phases
Drag the Moon around Earth and watch phases change in real-time. See why phases are geometry, not shadows.
Open Demo →lunar phases geometry illumination
Eclipse Geometry
Why don’t eclipses happen every month? Explore orbital tilt, nodes, and run 1000-year simulations.
Open Demo →eclipses orbital tilt nodes
Light & Spectra
Blackbody Radiation
See how temperature determines a star’s color and spectrum. Watch the Planck curve shift from infrared to ultraviolet.
Open Demo →blackbody Wien’s law Planck function
EM Spectrum Explorer
Journey from radio waves to gamma rays. See which telescopes observe each band and what objects emit there.
Open Demo →EM spectrum wavelength multiwavelength
Spectral Lines Lab
Practice Kirchhoff’s laws and use line-pattern fingerprints to identify elements in an unknown spectrum.
Open Demo →spectral lines Kirchhoff fingerprints
Doppler Shift Spectrometer
Move a radial-velocity slider and watch spectral lines shift. Connect sign, fraction shift, and velocity.
Open Demo →Doppler radial velocity spectroscopy
Telescopes & Observation
Angular Size
Why do the Sun and Moon look the same size? Explore how physical size and distance combine to create apparent size.
Open Demo →angular size scale small angle formula
Telescope Resolution
Why do bigger telescopes see finer detail? Explore diffraction limits, seeing, and adaptive optics.
Open Demo →resolution diffraction Rayleigh criterion
Orbits & Distances
Kepler’s Laws
Drag planets around elliptical orbits. See how speed changes with distance and why P² = a³.
Open Demo →Kepler’s laws elliptical orbits orbital period
Binary Orbits
Both bodies orbit the barycenter. Explore stellar wobble and how mass ratio sets orbit size and speed.
Open Demo →barycenter two-body exoplanets
Conservation Laws (Orbits)
Energy + angular momentum determine whether an orbit is bound (ellipse), escaping (parabola), or a flyby (hyperbola).
Open Demo →energy angular momentum escape velocity
Stellar Parallax
How do astronomers measure distances to nearby stars? Watch stars shift as Earth orbits the Sun.
Open Demo →parallax parsec Gaia mission
Planets & Climate
Planetary Climate Sandbox
Change albedo, greenhouse strength, and distance from the star — then see how equilibrium temperature and surface temperature respond.
Open Demo →climate greenhouse effect habitability