Habitable Worlds Observatory Archives

(a) The Earth’s extensive and H-rich exosphere scatters solar Lyman-α photons, producing the geocoronal airglow; (b) the geometry of Earth’s illumination by the Sun (adapted from Kameda et al. 2017). Due to its size, such a large exosphere can produce a potentially detectable absorption of stellar Lyman-α photons when observed in transit (Gomez de Castro et al. ´ 2018; Dos Santos et al. 2019a). -- astro-ph.IM

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Habitable Zones, Imaging & Spectroscopy, Status Report

Exoplanet Atmospheric Escape Observations with the Habitable Worlds Observatory

by Keith CowingJuly 11, 2025

The Decadal Survey on Astronomy and Astrophysics 2020 highlights the importance of advancing research focused on discovering and characterizing habitable worlds.

(a) Galileo Solid State Imaging (SSI) false color data of Europa’s leading hemisphere and Tara Regio (credit: NASA, JPL/Caltech, PIA01295). (b) Illustration of chaos on Europa (credit: NASA, GSFC, PIA00840), showing hypothesized geologic communication between its subsurface ocean and surface (chaos formation mechanisms summarized in e.g., Daubar et al. 2024). (c) Spectral map showing the distribution of irradiated NaCl on Europa, highlighting its concentration in and around Tara Regio (modified from Trumbo et al. 2019). -- astro-ph.IM

Ariel, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Ceres, Enceladus, Europa, Habitable Zones, Icy Worlds, Status Report, Water/Hycean Worlds & Oceanography

Assessing Ocean World Habitability With HWO

by Keith CowingJuly 11, 2025July 11, 2025

The instrument payload of the future Habitable Worlds Observatory (HWO) will span a wide range of wavelengths, including the ultraviolet (UV) region that cannot be easily accessed from the ground […]

Earth's limb as seen from space. Photo ISS001-421-24 3 March 2001 Larger image -- NASA

Analog Studies, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

A Statistical Method For Constraining the Capability of the Habitable Worlds Observatory to Understand Ozone Onset Time in Earth Analogs

by Keith CowingJuly 9, 2025July 9, 2025

The oxygenation of Earth’s atmosphere 2.3 billion years ago, which on exoplanets is expected to be most detectable via the UV ozone feature at ∼0.25 μm, is often regarded as […]

Left panel: amount of stellar flux received as a function of planetary radius for the sample of known exoplanets (black dots). F⊕ is the Earth’s incident irradiation from the Sun. The large blue dots show the position of Earth and Jupiter. The black and green labels denote the location where exoplanets are common (Jupiter, sub-Neptune, and rocky planets) and scarce (Neptune desert; radius valley, right panel), respectively. Right panel: radius valley distribution for planets in short-period orbits (Fulton et al. 2017). The structure in this distribution is believed to be the outcome of a combination of planet formation and planet evolution processes. -- astro-ph.IM

Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Press Release

High-resolution Ultraviolet-to-near Infrared Characterization Of Exoplanet Atmospheres

by Keith CowingJuly 9, 2025July 9, 2025

The Habitable Worlds Observatory (HWO) offers a unique opportunity to revolutionize our understanding of planetary formation and evolution.

Planetary reflectivity (top; total flux) and polarization (bottom; polarized flux) as a function of scattering angle (or phase angle) and wavelength (colors). Glories, rainbows, Rayleigh scattering, and ocean glint generate strong polarization signatures and subtle reflectance signatures. (Figure from Vaughan et al. 2023). -- astro-ph.IM

Astronomy & Telescopes, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

Detecting Surface Liquid Water On Exoplanets

by Keith CowingJuly 8, 2025July 8, 2025

Planets with large bodies of water on their surface will have more temperate and stable climates, and such planets are the ideal places for life-as-we-know-it to arise and evolve.

Left: The known exoplanet population (divided into two bins of masses above and below 10 Earth masses) as a function of their semi-major axis and of the central stellar mass. The classical habitable zone is shown by the blue area, and the region where star-planet magnetic interactions (SPMI) are expected to occur is shown by the red area, i.e. within the so-called Alfven surface. Right: Modelling of the wind of HD 189733 based on a spectropolarimetric map ( ´ Fares et al. 2017) showing the magnetic connectivity between the hot Jupiter HD 189733 b and its host (from Strugarek et al. 2022). -- astro-ph.IM

Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Habitable Zones, Imaging & Spectroscopy, Magnetic Fields, Electromagnetism, bioelectricity,, Status Report

Detecting And Characterising The Magnetic Field Of Exoplanets

by Keith CowingJuly 7, 2025July 7, 2025

Magnetic fields play a crucial role in planetary evolution and habitability. While the intrinsic magnetic fields of solar system planets are relatively well understood, the magnetic properties of exoplanets remain […]

A comparison of state-of-the-art geometric distances that serve to anchor the distance scale and their current relative uncertainties. Additional candidate (≲1 Mpc) eclipsing binary hosts to target in future are also pictured. Current EB distances to M31 and M33 rely on early-type stars and are not precise enough to be included in H0 determination (Vilardell et al. 2010; Bonanos et al. 2006), but we expect this will improve with more sensitive moderate- to high-resolution spectroscopy capable of characterizing late-type EB systems. -- astro-ph.CO

Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Interstellar, Status Report, Stellar Cartography

Envisioning The Distance Ladder In The Era Of The Habitable Worlds Observatory

by Keith CowingJuly 5, 2025

The current state-of-the-art cosmic distance ladder requires three rungs–geometric distances, primary indicators, and Type Ia Supernovae–to achieve a 1% measurement of the Hubble constant H0.

Distance vs. Stellar Mass for over 15,000 known galaxies out to 50 Mpc (Ohlson et al. 2024). Galaxies are colorcoded by their Hubble “T” Type, with early type galaxies T < 0 and late-type galaxies T > 0. The three stellar luminosity depth limits – RGB, sub-Red Clump, and sub-oMSTO – are shown as lines, corresponding to the distances where they are achievable for massive galaxies, and color-coded according to Fig. 1. The distances for these 3 depths achievable with HST and JWST are shown as dashed lines, while those achievable with HWO are shown as solid lines. The increase in galaxy diversity accessible from JWST→HWO is striking. The color bimodality of galaxies (e.g., Baldry et al. 2004) is visible within HWO’s reach, as is the Virgo Cluster which is notable as a vertical line of enhanced density. -- astro-ph.GA

Astronomy & Telescopes, Imaging & Spectroscopy, Status Report, Stellar Cartography

Resolving Individual Stars in Nearby Large Galaxies with the Habitable Worlds Observatory

by Keith CowingJuly 5, 2025July 5, 2025

The varied and dynamic evolutionary histories of galaxies give rise to the stunning diversity in their properties that we observe in the present-day universe.

Substructures in protoplanetary disks, such as (a) spiral arms and (b) gaps, can inform the location and mass of protoplanets that shape these substructures (marked with arrows here; e.g., Dong & Fung 2017; Bae et al. 2018). Note: the panels displayed here use simulated data provided by Dong et al. (2015) for (a) and Bi & Lin (2024) for (b). -- astro-ph.IM

Astronomy & Telescopes, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Mapping, Geodesy, Cartography, Bathymetry, Status Report

Studying Protoplanets and Protoplanetary Disks with the Habitable Worlds Observatory

by Keith CowingJuly 3, 2025July 3, 2025

Since the discovery of the first exoplanet orbiting a Sun-like star, the confirmation of nearly 6000 exoplanets to date – and their diversity – has revolutionized our knowledge of planetary […]

Schematic of the post-impact scenario for prebiotic atmospheres (Genda et al. 2017; Zahnle et al. 2020; Wogan et al. 2023). In this scenario, reducing power is delivered to the surface-atmosphere system by reaction of an iron-rich meteor with the planetary ocean, generating a transient Miller-Urey type atmosphere. We anticipate such atmospheres to be strongly distinguishable by HWO observations through their copious concentrations of reducing species (Goodis Gordon et al. 2025). However, we also anticipate such atmospheres to be rare due to their transient nature, and a sample of 25 planets is unlikely to capture them. Figure taken from Wogan et al. (2023). -- astro-ph.IM

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

Prebiosignatures With The Habitable Worlds Observatory (HWO)

by Keith CowingJuly 2, 2025July 2, 2025

The Habitable Worlds Observatory (HWO) aims to characterize habitable exoplanets in search of signs of life. However, detectable life may be rare, either because abiogenesis is intrinsically contingent and unlikely, […]

Habitable Worlds Observatory

Exoplanet Atmospheric Escape Observations with the Habitable Worlds Observatory

Assessing Ocean World Habitability With HWO

A Statistical Method For Constraining the Capability of the Habitable Worlds Observatory to Understand Ozone Onset Time in Earth Analogs

High-resolution Ultraviolet-to-near Infrared Characterization Of Exoplanet Atmospheres

Detecting Surface Liquid Water On Exoplanets

Detecting And Characterising The Magnetic Field Of Exoplanets

Envisioning The Distance Ladder In The Era Of The Habitable Worlds Observatory

Resolving Individual Stars in Nearby Large Galaxies with the Habitable Worlds Observatory

Studying Protoplanets and Protoplanetary Disks with the Habitable Worlds Observatory

Prebiosignatures With The Habitable Worlds Observatory (HWO)

Impact Crater Hydrothermal Systems Support Rapid Microbial Enrichment and Diverse Metabolic Potential

Photometric and Spectroscopic Observations of Comet 2P/Encke’s Nucleus in the Mid-Infrared Wavelength Region

A New Method Maps An Exoplanet’s True Shape

Wavefront-Conditioned Photon Measurements for Exoplanet Spectroscopy: Contrast Limits and Conditional Gains

ExoPAG 35 – Early Career Talks Invitation