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.
FAQ — Exoplanet Archive: NASA Confirmed Exoplanets Explorer & Habitability Finder
Frequently Asked Questions — Exoplanet Archive
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. Since then, NASA has confirmed over 5,000 exoplanets using space telescopes like Kepler, TESS, and ground-based observatories. They range from rocky Earth-sized worlds to gas giants many times larger than Jupiter.
What does the habitability score mean?
The habitability score (0–100) is calculated from several factors: whether the planet is in its star's habitable zone (where liquid water could exist), its size relative to Earth, its estimated surface temperature, and whether it orbits a stable star. A score above 70 suggests conditions that could theoretically support liquid water. This is a simplified estimate — actual habitability depends on atmosphere, magnetic field, and many other unknowns.
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, very difficult), and Microlensing (using gravity to bend light from a background star). Transit is the most productive method, responsible for about 75% of all discoveries.
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, it's roughly 0.95–1.37 AU. For a cooler red dwarf star like TRAPPIST-1, the habitable zone is much closer in. 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, 233-day orbit, in the habitable zone of a K-type star), Kepler-452b (often called "Earth's cousin," orbiting a G-type star similar to our Sun), and TRAPPIST-1e (0.92× Earth radius, in the habitable zone of a nearby ultracool dwarf star just 40 light-years away). Use the "Earth-like" filter to explore them all.
Where does this data come from?
All data is fetched from the NASA Exoplanet Archive maintained by Caltech's IPAC, using their TAP (Table Access Protocol) API. This is the same dataset used by professional astronomers worldwide. The archive is updated as new planets are confirmed. Data includes planet mass, radius, orbital period, equilibrium temperature, host star properties, and discovery metadata.
What do the planet types mean?
Terrestrial: rocky planets smaller than ~1.6× Earth radius. Super-Earth: rocky planets 1.6–3× Earth radius. Sub-Neptune: gaseous planets 3–6× Earth radius. Neptune-like: ice giants 6–12× Earth radius. Gas Giant: planets larger than 12× Earth radius, similar to Jupiter or Saturn. Hot Jupiter: gas giants orbiting extremely close to their star with periods under 10 days.
Is this tool free?
Yes, completely free with no signup, no ads, and no data collection. It is one of 90+ free tools at jasperbernaers.com.