Characterize exoplanets — compute gravity, density, equilibrium temperature, habitability, and compare with known worlds.
Since the discovery of the first exoplanet orbiting a Sun-like star in 1995, astronomers have confirmed over 5,700 exoplanets in more than 4,200 star systems. Characterizing these worlds—estimating their gravity, density, temperature, and potential habitability—is one of modern astronomy's central challenges.
With just a few measurable parameters such as a planet's radius, mass, and orbital distance from its star, we can derive a wealth of physical properties. Surface gravity determines whether an atmosphere can be retained. Equilibrium temperature indicates whether liquid water might exist. Density reveals whether a world is rocky, icy, or gaseous.
This exoplanet calculator lets you input any combination of known or hypothetical parameters to compute key properties, assess habitability, and compare your planet with famous exoplanets like Proxima Centauri b, TRAPPIST-1e, and Kepler-442b. It supports characterization, habitability assessment, and transit method analysis modes.
Use the preset examples to load common values instantly, or type in custom inputs to see results in real time. The output updates as you type, making it practical to compare different scenarios without resetting the page.
This calculator brings exoplanet science to life by letting you explore how different physical parameters affect a planet's properties and habitability. It's ideal for astronomy students, science communicators, and anyone fascinated by the search for Earth-like worlds beyond our solar system.
This tool is designed for quick, accurate results without manual computation. Whether you are a student working through coursework, a professional verifying a result, or an educator preparing examples, accurate answers are always just a few keystrokes away.
Surface gravity: g = GM/R². Escape velocity: v_esc = √(2GM/R). Equilibrium temperature: T_eq = T_star × √(R_star / 2d) × (1 − A)^0.25. Habitable zone inner: d_inner = √(L / 1.1). Habitable zone outer: d_outer = √(L / 0.53).
Result: Gravity ≈ 1.30 g; Temp ≈ 233 K; In Habitable Zone
Kepler-442b has 1.3× Earth gravity and an equilibrium temperature near 233 K (−40°C), placing it within its star's habitable zone.
Use consistent units throughout your calculation and verify all assumptions before treating the output as final. For professional or academic work, document your input values and any conversion standards used so results can be reproduced. Apply this calculator as part of a broader workflow, especially when the result feeds into a larger model or report.
Most mistakes come from mixed units, rounding too early, or misread labels. Recheck each final value before use. Pay close attention to sign conventions — positive and negative inputs often produce very different results. When working with multiple related calculations, keep intermediate values available so you can trace discrepancies back to their source.
Enter the most precise values available. Use the worked example or presets to confirm the calculator behaves as expected before entering your real data. If a result seems unexpected, compare it against a manual estimate or a known reference case to catch input errors early.
Key factors include being in the star's habitable zone (liquid water possible), having sufficient gravity to retain an atmosphere, and a suitable temperature range. This calculator assesses these basic criteria. This concept becomes clearer when you compare orbital inputs with known reference planets.
The range of orbital distances where liquid water could exist on a planet's surface, given sufficient atmospheric pressure. It depends on the star's. Use this interpretation rule before drawing conclusions from borderline habitability scores. luminosity and temperature.
Usually via the radial velocity method (measuring the star's wobble caused by the planet's. Keep interpretation aligned to data quality and assumptions before changing decisions. gravity) or by transit timing variations in multi-planet systems.
The theoretical surface temperature assuming the planet absorbs and re-radiates stellar energy in thermal equilibrium, without accounting for greenhouse effects. Use this as a practical reminder before finalizing the result.
Gas giants that migrated inward after forming farther out. They orbit very close to their stars (< 0.1 AU) with equilibrium temperatures exceeding 1000 K.
When a planet passes in front of its star, the star's brightness decreases slightly. The transit depth (dip fraction) reveals the planet's. This concept becomes clearer when you compare orbital inputs with known reference planets. radius relative to the star.