Every planet in this archive is given a Habitability Score from 0 to 100. This is not an official NASA metric — it is a simplified educational estimate that weighs four key factors scientists consider when evaluating whether a planet could support life as we know it.
| Factor | Max Points | What It Means |
|---|---|---|
| Habitable Zone | 35 pts | Is the planet in the "Goldilocks zone" — the orbital distance where liquid water could exist on the surface? This is the single biggest factor. The zone depends on the host star's luminosity. |
| Size Similarity to Earth | 25 pts | Planets closest to Earth's radius (1.0 R⊕) score highest. Radius within 0.3× Earth gets full marks. Larger worlds are more likely to be gaseous, and very small ones may lack atmosphere. |
| Equilibrium Temperature | 25 pts | The ideal range is 200–320 K (roughly −73 to +47 °C). This is where water could exist as a liquid. Scorching hot Jupiters or frozen ice worlds score low. |
| Host Star Type | 15 pts | Stars between 3,800–7,000 K (spectral type late-K to F) are considered most favorable. They are stable, long-lived, and emit radiation compatible with photosynthesis. Very cool M-dwarfs score lower due to tidal locking and stellar flares. |
A high score does not mean life exists there — it means conditions are less hostile to life as we understand it. We have no direct evidence of life on any exoplanet. Real habitability depends on atmosphere composition, magnetic fields, tidal locking, stellar activity, and many unknowns we cannot yet measure remotely.
Equilibrium Temperature (Teq) is the theoretical surface temperature a planet would have if it were a perfect blackbody with no atmosphere. It is calculated from the star's luminosity and the planet's orbital distance. The actual surface temperature can be very different — Earth's equilibrium temperature is about 255 K (−18 °C), but our atmosphere adds a greenhouse effect bringing it to ~288 K (+15 °C).
Key units used throughout this archive:
Star Temperature (Teff) is the "effective temperature" of the host star's photosphere. It tells you the star's color and energy output: cool red dwarfs at 2,500–3,800 K, orange K-type at 3,800–5,300 K, yellow G-type (like our Sun at 5,778 K), hot F-type at 6,000–7,500 K, and blue-white A-type stars above 7,500 K. Cooler stars have their habitable zone much closer in.
Insolation (S⊕) measures how much energy a planet receives compared to Earth. A value of 1.0 means it gets the same stellar energy as Earth. Planets in the habitable zone typically have insolation between 0.25 and 1.75 S⊕. Venus receives about 1.9 S⊕ (too hot), while Mars gets about 0.43 S⊕ (too cold for liquid water on the surface).
This archive classifies every planet into one of six categories based on its radius, mass, and orbital characteristics:
| Type | Radius | Description |
|---|---|---|
| Terrestrial | ≤ 1.6 R⊕ | Rocky worlds similar to Earth, Venus, or Mars. Most likely to have solid surfaces and potentially thin atmospheres. These are the prime targets in the search for life. |
| Super-Earth | 1.6–3.0 R⊕ | Bigger than Earth but smaller than Neptune. Could be rocky with thick atmospheres or ocean worlds. Some may have extreme surface pressure. No equivalent exists in our solar system. |
| Sub-Neptune | 3.0–6.0 R⊕ | Mini gas planets with thick hydrogen/helium envelopes. Likely no solid surface, but may have deep liquid layers. The most common type of planet in the galaxy — yet absent from our own solar system. |
| Neptune-like | 6.0–12 R⊕ | Ice giants similar to Neptune and Uranus. Composed of water, ammonia, and methane ices surrounding a rocky core, wrapped in a thick hydrogen atmosphere. |
| Gas Giant | > 12 R⊕ | Massive worlds like Jupiter and Saturn. Composed almost entirely of hydrogen and helium with no discernible solid surface. Long orbital periods (years to decades). |
| Hot Jupiter | > 12 R⊕, P < 10d | Gas giants that orbit extremely close to their star (often closer than Mercury to the Sun). Surface temperatures can exceed 2,000 K. They were among the first exoplanets discovered because they are easiest to detect. |
Featured Planet Panel — the top-left card shows a randomly selected planet with a procedural visualization, full stats, Earth comparison bars, habitability meter, and estimated travel times at different speeds. Click 🎲 Random to discover a new world, or click any planet in the catalog list to feature it.
Filters & Search — use the filter tabs at the top of the catalog to narrow down by type: Earth-like, Habitable Zone, Super-Earths, Gas Giants, Neptune-like, Hot Jupiters, Nearest (<50 ly), or recently discovered (2023+). The search box matches planet names, hostnames, and discovery facilities. Combine filters with sorting by habitability, distance, size, discovery year, temperature, or alphabetically.
Travel Time Estimates — for each featured planet, we calculate how long it would take to reach it at five benchmark speeds: Voyager 1 (17 km/s), New Horizons (14.31 km/s), Parker Solar Probe at peak velocity (192 km/s), 1% of light speed (futuristic), and 10% of light speed (science fiction). Even the nearest star Proxima Centauri is over 4 light-years away — about 75,000 years at Voyager speed.
Sidebar Charts — the right column shows a discovery timeline canvas chart (bar chart by year), quick stats grid, and a discovery methods breakdown showing what percentage were found by transit, radial velocity, imaging, or other techniques.
Discovery Methods Quick Reference: Transit — detects the tiny dip in starlight when a planet crosses in front of its star (accounts for ~75% of discoveries). Radial Velocity — measures the wobble a planet's gravity induces on its star. Direct Imaging — photographs the planet directly (only works for large, young, distant-orbit planets). Microlensing — uses gravitational bending of light from a background star. Transit Timing Variations — detects additional planets by the gravitational tugs they cause on known transiting planets.
Guide — browse every confirmed exoplanet and find the most Earth-like worlds
Loads the NASA Exoplanet Archive catalogue in your browser: filters, search, a habitability score per planet, travel times and four charts.On page load the app queries the NASA Exoplanet Archive TAP service (table pscomppars, one row per confirmed planet), with a 15-second timeout and two public CORS proxies as fallback. The header then shows Confirmed Worlds, Potentially Habitable (score 50+) and the nearest planet in light-years.
Press 🎲 Random, click a row in the catalogue or click a dot in the Population Explorer. The card shows radius, mass, orbital period, equilibrium temperature, distance, star temperature, semi-major axis, eccentricity, the habitability meter, Earth comparison bars and travel times at five speeds.
Use the nine filter tabs (All, Earth-like, Habitable Zone, Super-Earths, Gas Giants, Neptune-like, Nearest <50 ly, Hot Jupiters, Discovered 2023+); each shows its live count. The search box matches planet name, host star, discovery method, planet type and discovery facility.
Sort by Habitability ↓, Nearest First, Largest First, Newest First, Temperature ↑ or Name A→Z. The list shows 40 planets per page with ← Prev and Next →.
The sidebar has Discoveries by Year, Archive Stats and a count per discovery method. Below, the Population Explorer plots radius against insolation (hover for details, click to feature) and the radius histogram shades the 1.5–2.0 R⊕ radius gap.
Quick reference
- habitable zone
- 35 points
- size
- 25 points, full marks within 0.3 R⊕ of Earth
- temperature
- 25 points, full marks at 200–320 K
- host star
- 15 points, full marks at 3,800–7,000 K
- terrestrial
- up to 1.6 R⊕
- super-Earth / sub-Neptune
- 1.6–3 R⊕ / 3–6 R⊕
- Neptune-like
- 6–12 R⊕
- gas giant
- over 12 R⊕; hot Jupiter if the orbit is under 10 days
- with insolation
- 0.25–1.75 times what Earth receives
- without
- zone computed from star radius and temperature, compared with the orbit
- score labels
- 70+ High · 40–69 Moderate · 20–39 Low · under 20 Very Low
Exoplanets, explained
An exoplanet is a planet orbiting a star other than the Sun. This explorer loads the confirmed planets from the NASA Exoplanet Archive and gives each one a simple, unofficial habitability score, so you can quickly find the worlds that are closest to Earth in size, temperature and orbit.
What is an exoplanet?
An exoplanet is any planet that orbits a star outside our solar system. The first confirmed exoplanet around a Sun-like star, 51 Pegasi b, was discovered in 1995. The NASA Exoplanet Archive now lists more than 6,000 confirmed exoplanets, found with space telescopes such as Kepler and TESS and with ground-based observatories; the counter at the top of this page shows the current number. They range from rocky worlds smaller than Earth to gas giants many times larger than Jupiter.
What does the habitability score mean?
The habitability score (0–100) is this app's own simplified estimate, not an official NASA metric. It adds four parts: 35 points if the planet is in its star's habitable zone, up to 25 points for a radius close to Earth's, up to 25 points for an equilibrium temperature between 200 and 320 K, and up to 15 points for a host star between 3,800 and 7,000 K. Scores of 70 and up are labelled High, 40–69 Moderate, 20–39 Low and below 20 Very Low. Missing measurements simply earn no points, and real habitability also depends on atmosphere, magnetic field and much more that the score cannot see.
How are exoplanets discovered?
The main methods are: Transit (watching a star dim slightly as a planet crosses in front, used by Kepler and TESS), Radial Velocity (measuring the star's wobble caused by a planet's gravity), Direct Imaging (photographing the planet directly, which is very difficult) and Microlensing (a foreground star and planet bending the light of a background star). Transit is by far the most productive method, with roughly three quarters of all confirmed planets. The Discovery Methods panel counts every method in the loaded catalogue.
What is the habitable zone?
The habitable zone (or "Goldilocks zone") is the region around a star where a planet's surface temperature could allow liquid water to exist: not too hot, not too cold. It depends on the star's luminosity: for our Sun a commonly used conservative estimate is roughly 0.95–1.37 AU, and for a cool red dwarf such as TRAPPIST-1 it lies much closer in. This app counts a planet as in the zone when it receives between 0.25 and 1.75 times Earth's insolation; when insolation is missing it estimates the zone from the star's radius and temperature. Being in the habitable zone doesn't guarantee life: it's a necessary but not sufficient condition.
Which exoplanet is most like Earth?
Several candidates score highly: Kepler-442b (1.34× Earth radius, a 112-day orbit in the habitable zone of a K-type star), Kepler-452b (often called "Earth's cousin", about 1.6× Earth radius with a 385-day orbit around a Sun-like G-type star) and TRAPPIST-1e (0.92× Earth radius, in the habitable zone of an ultracool dwarf star about 40 light-years away). Sort by Habitability ↓ to see the top scorers. The Earth-like filter shows terrestrial planets (up to 1.6 R⊕) with a score of 40 or more, so slightly larger worlds such as Kepler-452b appear under Super-Earths instead.
Where does this data come from?
The data comes from the NASA Exoplanet Archive, run by Caltech/IPAC. When the page opens, your browser queries its public TAP (Table Access Protocol) service for the pscomppars table, which has one row per confirmed planet with radius, mass, orbital period, semi-major axis, equilibrium temperature, eccentricity, distance, host star properties and discovery metadata. If the direct request fails, the page retries through the public CORS proxies allorigins.win and corsproxy.io. The catalogue is loaded once per visit; reload the page for the latest version. If every source fails, the page says so and shows a fallback of 31 real planets plus 1,200 procedurally generated example planets, so those numbers are not real data. Only the public catalogue is requested; nothing you search or click is sent anywhere.
What do the planet types mean?
The app classifies each planet by its radius; when only the mass is known, it estimates a radius from the mass. Terrestrial: up to 1.6× Earth radius, likely rocky. Super-Earth: 1.6–3× Earth radius. Sub-Neptune: 3–6× Earth radius, likely with a thick gas envelope. Neptune-like: 6–12× Earth radius. Gas Giant: larger than 12× Earth radius, like Jupiter or Saturn. Hot Jupiter: a gas giant with an orbital period under 10 days. Planets with neither radius nor mass are listed as Unknown.