Exoplanet Explorer

Browse and filter thousands of known exoplanets

Search the exoplanet catalog by discovery method, size, orbital period, host star type, and habitability indicators. View detailed profiles of notable exoworlds.

How to Use

  1. 1
    Filter the catalog by discovery method and planet type

    Select from transit, radial velocity, direct imaging, microlensing, or astrometry detection methods. Apply size filters for Earth-sized, super-Earth, Neptune-sized, or Jupiter-sized planets, and set orbital period ranges to identify short-period hot Jupiters or potentially habitable long-period worlds.

  2. 2
    Apply habitability and host star filters

    Filter by habitable zone orbital distance, host star spectral type, and stellar age to narrow the catalog to potentially temperate rocky worlds. The tool queries the NASA Exoplanet Archive and calculates equilibrium temperatures and Earth Similarity Index scores for each candidate.

  3. 3
    View detailed profiles of selected exoplanets

    Click any entry to access the full data profile including mass, radius, density, orbital eccentricity, atmospheric characterization status, and discovery paper references. Compare multiple planets side by side on a mass-radius diagram to infer bulk compositions from theoretical interior models.

About

Exoplanet science has transformed from a speculative field into one of astronomy's most productive frontiers within three decades. The 1992 detection of planets around the pulsar PSR 1257+12 by Aleksander Wolszczan and Dale Frail, and the 1995 discovery of the hot Jupiter 51 Pegasi b by Michel Mayor and Didier Queloz (who shared the 2019 Nobel Prize in Physics), established radial velocity as the first reliable method for finding planets around main-sequence stars. These early discoveries challenged planetary formation models by revealing planets in configurations not found in our solar system.

The Kepler Space Telescope, operating from 2009 to 2018, revolutionized the field by demonstrating that planets are extraordinarily common throughout the galaxy. Statistical analyses of Kepler data show that nearly every star hosts at least one planet on average, and that the most common planet type in the galaxy, the super-Earth and sub-Neptune class between 1 and 4 Earth radii, is entirely absent from our solar system. The TESS mission extends Kepler's legacy by covering the entire sky and focusing on bright nearby stars more amenable to follow-up characterization.

The central question of exoplanet science today is whether any of the billions of rocky planets in habitable zones host environments capable of supporting life. The James Webb Space Telescope, with its extraordinary infrared sensitivity, is conducting the first systematic atmospheric surveys of potentially temperate rocky worlds including the TRAPPIST-1 system. Future facilities including the Extremely Large Telescope, the Habitable Worlds Observatory, and the European LIFE mission are designed specifically to detect atmospheric biosignatures and conduct comparative planetology across dozens of nearby exoplanet systems.

FAQ

How many exoplanets have been confirmed as of 2025?
As of early 2025, the NASA Exoplanet Archive lists over 5,700 confirmed exoplanets across more than 4,200 planetary systems, with thousands of additional candidates awaiting confirmation. The majority were discovered by the Kepler and K2 missions using the transit method. The TESS mission launched in 2018 has added hundreds more confirmed planets and continues to generate thousands of new candidates. Ground-based radial velocity surveys, direct imaging programs, and microlensing surveys contribute the remainder, each method sensitive to different orbital architectures and mass ranges.
What is the transit method and why does it dominate the catalog?
The transit method detects exoplanets by measuring the fractional dimming of a star's light as a planet passes in front of it. A Jupiter-sized planet dims a solar-type star by about 1% while an Earth-sized planet causes a dimming of only 0.01%. Space-based photometers like Kepler and TESS can detect these tiny signals continuously over thousands of stars simultaneously. The transit method also reveals the orbital period directly and, when combined with radial velocity measurements, yields the planet's density. Its dominance in the catalog reflects the efficiency of monitoring large stellar populations from space.
What is the Earth Similarity Index?
The Earth Similarity Index (ESI) is a dimensionless measure from 0 to 1 that compares a planet's radius, density, escape velocity, and surface temperature to Earth's values. An ESI of 1.0 would represent an exact Earth twin. Mars has an ESI of about 0.64, Venus about 0.44. Among known exoplanets, TRAPPIST-1e and Teegarden's Star b have ESI values above 0.90, making them the most Earth-like confirmed planets by this metric. The ESI is a heuristic ranking tool rather than a definitive habitability assessment, which requires detailed atmospheric and geologic information.
How do we measure the mass and radius of an exoplanet?
Planetary radius is measured from the transit depth using the ratio of planet to stellar radius: (R_p/R_☆)² equals the fractional flux decrease during transit. Stellar radii are determined from spectroscopic analysis and stellar models, calibrated by interferometric measurements of nearby bright stars. Planetary mass is measured by the radial velocity method, which detects the Doppler wobble of the host star induced by the planet's gravitational pull. The combination of mass and radius yields bulk density, which constrains whether the planet is predominantly rocky, water-rich, or gas-dominated using theoretical mass-radius relationships.
What has atmospheric characterization revealed about exoplanet atmospheres?
Transmission spectroscopy during transits probes the wavelength-dependent opacity of exoplanet atmospheres. The Hubble Space Telescope detected water vapor in the atmospheres of numerous hot Jupiters and sub-Neptunes. The James Webb Space Telescope has provided the first detailed atmospheric spectrum of a rocky exoplanet (TRAPPIST-1c), constrained carbon dioxide and methane in the sub-Neptune GJ 1214b, and detected carbon dioxide in the hot Jupiter WASP-39b among many other detections. Biosignature gases like oxygen, ozone, and methane in combination remain targets for future extremely large telescopes and dedicated missions.