Current Number of Potentially Habitable Exoplanets


subterran = 0.1 — 0.5 ME or 0.4 — 0.8 REterran = 0.5 — 5 ME or 0.8 — 1.5 RE, superterran = 5 — 10 ME or 1.5 — 2.5 REME = Earth masses, and RE = Earth radii.

Conservative Sample of Potentially Habitable Exoplanets

This is a list of the exoplanets that are more likely to have a rocky composition and maintain surface liquid water (i.e. 0.5 < Planet Radius ≤ 1.5 Earth radii or 0.1 < Planet Minimum Mass ≤ 5 Earth masses, and the planet is orbiting within the conservative habitable zone). They are represented artistically in the top image.

Optimistic Sample of Potentially Habitable Exoplanets

This is a list of the exoplanets that are less likely to have a rocky composition or maintain surface liquid water (i.e. 1.5 < Planet Radius ≤ 2.5 Earth radii or 5 < Planet Minimum Mass ≤ 10 Earth masses, or the planet is orbiting within the optimistic habitable zone).

Tables Legend

  • Name - Name of the planet. This links to the data of the planet at the NASA Exoplanet Archive.
  • Type - PHL's classification of planets that includes host star spectral type (F, G, K, M), habitable zone location (hot, warm, cold) and size (miniterran, subterran, terran, superterran, jovian, neptunian) (e.g. Earth = G-Warm Terran, Venus = G-Hot Terran, Mars = G-Warm Subterran).
  • Mass - Mass of the planet in Earth masses (Earth = 1.0 ME).
  • Radius - Radius of planet in Earth radii (Earth = 1.0 RE).
  • Flux - Average stellar flux of the planet in Earth fluxes (Earth = 1.0 SE).
  • Teq - Equilibrium temperature in kelvins (K) assuming a 0.3 bond albedo (Earth = 255 K). Actual surface temperatures are expected to be larger than the equilibrium temperature depending on the atmosphere, which are currently unknown (e.g. Earth mean global surface temperature is about 288 K or 15°C).
  • Period - Orbital period in days (Earth = 365 days).
  • Distance - Distance from Earth in light-years (ly).
  • ESI - Earth Similarity Index, a measure of similarity to Earth's stellar flux, mass, and radius (Earth = 1.0). Results are sorted by this number. Planets more similar to Earth are not necessarily more habitable, since the ESI does not consider all factors necessary for habitability.

The figure above shows all planets near the habitable zone (darker green shade is the conservative habitable zone and the lighter green shade is the optimistic habitable zone). Only those planets less than 10 Earth masses or 2.5 Earth radii are labeled. The different limits of the habitable zone are described in Kopparapu et al. (2014). Size of the circles corresponds to the radius of the planets (estimated from a mass-radius relationship when not available). Larger version here. Credit: PHL @ UPR Arecibo.

Location in the night sky of all the known stellar systems with potentially habitable worlds (some systems have more than one planet). Click the image to enlarge. Larger version hereCredit: PHL @ UPR Arecibo, Jim Cornmell.

HEC: Periodic Table of Exoplanets

The Periodic Table of Exoplanets shows all known exoplanets, including a few still unconfirmed, classified into eighteen thermal-mass categories. The number of exoplanets in each category is shown in the center of each frame and as a percent in the lower left. The figure also shows the number of multiple stellar systems (top right). Credit: PHL @ UPR Arecibo