Astronomy & Space
Orbital mechanics, rocket equations, and planetary physics. Explore the solar system and beyond.
Orbital Mechanics & Astrodynamics
- Escape Velocity Comparator — Compare escape velocities across planets, stars, and extreme objects. The neutron star entry (~0.64c) puts everything else in perspective.
- Hill Sphere Calculator — Estimate a body's gravitational sphere of influence and practical moon-stability range.
- Hohmann Transfer Calculator — Calculate the two Δv burns needed to transfer between circular orbits and visualise the transfer ellipse.
- Kepler Orbit Visualiser — Visualise elliptical orbits and explore Kepler's three laws of planetary motion
- Orbital Period Calculator — Calculate orbital periods using Kepler's Third Law. Input semi-major axis and central body to find how long an orbit takes, from ISS to planetary orbits.
- Radial Velocity Semi-Amplitude — Compute stellar wobble amplitude K or infer minimum planet mass from RV measurements.
- Sphere of Influence Calculator — Estimate Laplace sphere-of-influence radius and compare against Hill radius.
- Synodic Period Calculator — Compute conjunction/opposition repeat cycles from two orbital periods.
- Tisserand Parameter Calculator — Compute Tisserand parameter relative to a perturbing planet and classify orbit families.
- Vis-Viva Equation — Calculate orbital velocity at any point in an orbit using the vis-viva equation
Stellar Physics & Evolution
- Black Hole Calculator — Calculate Schwarzschild radius, photon sphere, ISCO, Hawking temperature, and evaporation time for any black hole mass.
- Blackbody Radiation Explorer — Plot a normalized Planck spectrum and track Wien peak shift with temperature.
- Photon Energy Calculator — Compute photon energy from wavelength or frequency
- Solar Luminosity Comparison — Compare stellar luminosity to the Sun using radius and temperature scaling.
- Stefan-Boltzmann Sun Power Calculator — Compute blackbody surface flux and total luminosity from radius and temperature
- Stellar Evolution Explorer — Explore how stellar mass controls luminosity, main-sequence lifetime, spectral class, and compact remnant.
- Stellar Magnitude Calculator — Convert between apparent magnitude, absolute magnitude, and distance using the distance modulus
- Supernova Expansion Estimator — Estimate supernova remnant radius and angular size from expansion speed, age, and distance.
- Wien's Law Peak Wavelength Tool — Calculate blackbody peak wavelength from temperature and classify spectral band
Gravity & Dynamics
- 3-Body Problem Simulator — Interactive three-body gravity simulation showing chaos and sensitivity to tiny initial differences.
- Gravitational Lensing — Visualise Einstein rings and arc pairs — compute the Einstein radius, image positions, and magnification for a point-mass gravitational lens.
- Gravitational Wave Calculator — Calculate chirp mass and inspiral properties for binary mergers, LIGO-style.
- Lagrange Point Stability Explorer — Perturb test particles near Lagrange points and compare bounded vs diverging motion.
- Newtonian Gravity Explorer — Calculate gravitational force between any two masses and build intuition for the inverse-square law.
- Roche Limit Calculator — Estimate tidal disruption distance for a satellite near a primary body.
Astrobiology & Planetary Science
- Drake Equation Explorer — Estimate communicating civilizations with interactive Drake factors and challenge mode.
- Earth-like Planet Probability — Estimate expected Earth-like exoplanet counts from survey assumptions and detection efficiency.
- Exoplanet Transit Simulator — Simulate a planet transiting its star and see the resulting light curve dip
- Habitable Zone + Climate Toy — Explore how luminosity, albedo, greenhouse offset, and orbit set equilibrium temperature and habitable-zone placement.
- Moon Phase Calculator — Compute lunar phase, illumination, moon age, next full/new moon, and angular diameter for any date — with a high-res live moon diagram and synodic cycle strip.
- Planetary Density Calculator — Compare mass, radius, and bulk density across planets to infer interior composition — from icy moons to iron worlds.
Cosmology & Observation
- Angular Size Converter — Convert physical size and distance into apparent angular diameter in radians, degrees, arcminutes, and arcseconds.
- Astro Doppler Shift Calculator — Compute redshift and radial velocity from rest and observed wavelength or frequency.
- Astronomy Unit Converter — Convert astronomy length units and angular units with explicit dimensional separation.
- Cosmic Distance Ladder — Step through parallax, Cepheids, and Type Ia supernovae to measure astronomical distances
- Cosmological Redshift Calculator — Calculate recession velocity, lookback time, comoving distance, and scale factor from cosmological redshift z.
- Light Travel Time Calculator — Convert astronomical distance into one-way light travel time
Other Tools
- Orbital Resonance Checker — Find nearest low-order period resonance and detuning from measured orbital periods.
- Tsiolkovsky Rocket Equation — Explore how delta-v, specific impulse, and mass ratio connect. See the logarithmic curve that governs all rocketry - and why rockets are mostly fuel.