Exoplanet Universe

Data Source and Processing

The source dataset is a composite table query from the NASA Exoplanet Archive (Caltech/IPAC), accessed March 2026. Each of the 6,150 confirmed exoplanets carries 15 fields: planet name, right ascension (deg), declination (deg), distance (ly), discovery year, detection method, planet radius (R_⊕), equilibrium temperature (K), habitable zone flag, planet mass (M_⊕), orbital period (days), semi-major axis (AU), eccentricity, host star properties (name, effective temperature, radius, mass, spectral type), and discovery facility.

The full archive export (~50 MB CSV) is reduced to a 1.1 MB compact JSON by abbreviating field names, dropping columns not needed for visualization, and omitting null values rather than storing them explicitly. All 6,150 planets are retained regardless of data completeness—planets with missing radii, temperatures, or orbital elements are included and handled by the estimation cascade described below. This keeps the dataset small enough to load in a single HTTP request without pagination or a backend API.

Coordinate Mapping

The coordinate system is heliocentric: Earth sits at the origin, and all planets are positioned relative to the Sun. Each planet's equatorial coordinates (right ascension α, declination δ) are converted to 3D Cartesian (x, y, z) via standard spherical-to-Cartesian transformation. Because confirmed exoplanets span distances from 4.2 light-years (Proxima Centauri b) to over 27,000 light-years, a linear distance scale would collapse the nearby systems into a single point. Distance is therefore logarithmically scaled:

This compresses the 0–30,000 light-year range into 0–900 scene units, preserving the angular distribution of systems on the sky while keeping distant discoveries visible. The trade-off: angular separations (RA/Dec) are faithfully preserved, but radial distances are nonlinear. A cluster of stars that is roughly spherical in physical space may appear elongated or compressed along the radial axis in the visualization. Concentric distance rings at 10, 100, and 1,000 light-years provide scale context for the viewer.

Planet Classification

Planets are classified into four size categories following the scheme used by the NASA Exoplanet Archive and the Kepler mission team. The boundaries correspond to physical transitions in planet structure: below ~1.6 R_⊕, planets are predominantly rocky with thin or no atmospheres; between 1.6–3.0 R_⊕, volatile envelopes become significant; above ~8 R_⊕, hydrogen-helium dominated gas giants prevail.

• Rocky (<1.6 R_⊕) — Terrestrial planets with silicate/iron composition. Analogs: Mercury, Venus, Earth, Mars.
• Super-Earth (1.6–3.0 R_⊕) — No Solar System analog. May be rocky with thick atmospheres, ocean worlds, or mini-Neptunes. The most common planet type in the galaxy.
• Neptune-like (3.0–8.0 R_⊕) — Ice giants with hydrogen/helium envelopes over water-ammonia-methane interiors. Analogs: Uranus, Neptune.
• Gas Giant (>8.0 R_⊕) — Hydrogen-helium dominated. Includes hot Jupiters (P < 10 days), warm Jupiters, and cold gas giants. Analogs: Jupiter, Saturn.

Of the 6,150 planets, 1,582 lack measured radii and are classified by mass-radius relations or left unclassified. Habitable zone status follows the conservative limits of Kopparapu et al. (2013), which define the region where liquid water could persist on a rocky planet surface.

Temperature Estimation

Approximately 72% of planets in the archive lack a directly measured equilibrium temperature. For visualization purposes (surface color mapping and class assignment), a 5-tier estimation cascade fills in physically motivated defaults:

1. Direct measurement from the archive (available for ~28% of planets)
2. Equilibrium temperature from semi-major axis and stellar luminosity: T_eq = T_star × √(R_star / 2a) × (1−A)^1/4, assuming Bond albedo A = 0.3
3. Semi-major axis derived from orbital period via Kepler's third law (a³ = P² × M_star), then Tier 2 applied
4. Host star temperature heuristic for planets with known host but no orbital data: T_planet ≈ 0.117 × T_star
5. Detection method heuristic for remaining planets: Transit = 700 K (median of transit discoveries), RV = 500 K, Direct Imaging = 250 K, Other = 400 K

These are equilibrium temperatures assuming a bare surface with no atmosphere. The cascade does not model greenhouse warming, tidal heating, or albedo variations—a Venus-like planet with a thick CO₂ atmosphere would have a true surface temperature far above its equilibrium value. The estimates are clearly labeled in the per-planet information panel. The cascade is designed to degrade gracefully: each tier is less precise than the last, but all produce temperatures within the physically plausible range for the given detection context.

Visual Representation

No imaging technology can resolve the surface of an exoplanet. Planet textures in this visualization are therefore illustrative, not observational. They are generated from 49 base images sourced from NASA/JPL-Caltech Solar System imagery and Solar System Scope, transformed into 166 unique surface maps using class- and temperature-appropriate color palettes.

Seven manipulation axes produce visual diversity: hue rotation, brightness, per-channel color tint (RGB multiplication), contrast, saturation, horizontal longitude rotation, and hemisphere flip. Palettes are constrained by what atmospheric and surface chemistry predicts for each class:

• Rocky — grays, browns, reds, oranges (regolith, iron oxide, silicate surfaces)
• Super-Earth — blues (deep oceans), whites (ice/cloud cover), tans (arid surfaces)
• Neptune-like — blues, teals, cyans (methane and H₂ Rayleigh scattering)
• Gas Giant — oranges, browns, tans, deep blues (ammonia clouds, phosphine, methane bands)

The horizontal longitude rotation and hemisphere flip are particularly important for breaking up recognizable features from the source imagery—without them, Jupiter's Great Red Spot or Saturn's polar hexagon could appear on unrelated exoplanets. A Halton quasi-random sequence ensures maximum visual diversity between siblings sharing a base texture. All textures are rendered at 2048×1024 resolution on equirectangular projection, mapped onto spherical geometry.

3D Rendering

The visualization is built on Three.js r128 (WebGL) as a single HTML file with no build step or external dependencies beyond CDN-hosted libraries. The rendering is split into two tiers optimized for different levels of detail:

• 137 featured planets — individually modeled as sphere meshes with Phong shading, unique surface textures, and 3D text labels. Selected by a data-completeness scoring algorithm that favors planets with the most measured physical properties.
• 6,013 background planets — rendered as a GPU-accelerated point cloud in a single draw call. A custom shader colors each point by equilibrium temperature and scales its size by camera distance. Clicking any point promotes it to a full mesh with texture and info panel.

Post-processing applies a conservative bloom pass for star glow. An adaptive quality system monitors frame rate and automatically reduces resolution, particle counts, and effects on slower hardware to maintain interactive performance.