Radiation Archives

The incident photon flux density for the modern-day Earth (black), Archean Earth at 2.65 Ga (blue), and TRAPPIST-1e (red). The spectral resolution has been reduced for clarity. The shaded regions represents three relevant bandpasses for photosynthesis: standard PAR (0.40-0.70 µm), extended PAR (0.40-0.75 µm), and anoxic PAR (0.40-1.1 µm). -- astro-ph.EP

Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Origin & Evolution of Life, Radiation, Space Weather & Heliophysics, Status Report, Terraforming & Geoengineering, TRAPPIST-1

Dearth of Photosynthetically Active Radiation Suggests No Complex Life on Late M-Star Exoplanets

by Keith CowingJanuary 7, 2026January 7, 2026

The rise of oxygen in the Earth’s atmosphere during the Great Oxidation Event (GOE) occurred about 2.3 billion years ago. There is considerably greater uncertainty for the origin of oxygenic […]

Illustration of flare heating in three types of stars. The dashed line marks the stellar surface; blue areas show the quiet atmosphere, and red areas show regions heated during a white-light flare. Vertical arrows indicate the radiative output, with length proportional to intensity. In solar-like stars (left), heating is regulated by hydrogen ionization, which limits temperatures of white-light flares to ∼ 9000 K. In late M dwarfs like TRAPPIST-1 (middle), molecular hydrogen dissociation acts as a thermostat, capping temperatures of white-light flares near ∼ 3500 − 4000 K. In early M dwarfs (right), insufficient concentration of H2 means the dissociation thermostat is ineffective, allowing higher white-light flare temperatures. -- astro-ph.SR

Exoplanets, -moons, -comets, Radiation, Space Weather & Heliophysics, Status Report, TRAPPIST-1

Molecular Hydrogen Controls The Temperatures Of Flares On TRAPPIST-1

by Keith CowingJanuary 6, 2026January 6, 2026

Early JWST observations of TRAPPIST-1 have revealed an unexpected puzzle: energetic white-light flares (E>1030 erg) reach temperatures of only ∼3500–4000,K, nearly three times cooler than typical solar flares, which peak […]

This image from a map of Jezero Crater shows the area NASA’s Perseverance Mars rover is currently exploring, including Belva Crater, just below the center of the image. Credit: NASA/JPL-Caltech/University of Arizona/USGS-Flagstaff/JHU-APL -- NASA Larger image

Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Habitable Zones, Mapping, Geodesy, Cartography, Bathymetry, Mars, Missions & Hardware, Radiation, Robotics/Rovers/UAVs, Sample Return, Status Report

Recent Production Rates Of Cosmogenic Nuclides In The Igneous Rocks of Jezero Crater Floor, Mars

by Keith CowingJanuary 2, 2026January 2, 2026

The Perseverance rover has collected rock samples from the floor of Jezero crater, Mars, set to be returned to Earth through the Mars Sample Return (MSR) mission. These surface rocks […]

Cladosporium sphaerospermum (UAMH 4745) on potato dextrose agar after incubation for 14 days at 25°C. -- Wikipedia

Away Teams & Field Reports, Extremeophiles and Extreme Environments, Microbiology & Virology, Planetary Protection & Biosafety, Radiation, Sample Return, Status Report

Fungi From Chernobyl: Mycobiota Of The Inner Regions Of The Containment Structures Of The Damaged Nuclear Reactor

by Keith CowingDecember 30, 2025December 30, 2025

Extensive fungal growth has been detected on the walls and other building constructions in the inner parts of the Shelter of the damaged fourth Unit of the Chernobyl Nuclear Power […]

This illustration shows a red dwarf star orbited by a hypothetical exoplanet. -- NASA source

Exoplanets, -moons, -comets, Habitable Zones, Press Release, Radiation, Space Weather & Heliophysics

Habitability Of Exoplanets Orbiting Flaring Stars

by Keith CowingDecember 29, 2025December 29, 2025

As of late 2025 there are about 70 exoplanets that meet the formal criterion of having equilibrium temperatures allowing the presence of liquid water and about 50 of them orbit […]

Inouye Solar Telescope image of a solar flare on August 8, 2024. (Image credit: NSF/NSO/AURA, CC-BY)

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Radiation, Space Weather & Heliophysics, Status Report, Stellar Cartography

Transients As Determinants Of Habitability

by Keith CowingDecember 19, 2025December 19, 2025

Stellar magnetic activity, manifested through spots (faculae and flares), fundamentally shapes the exoplanets’ environments.

The lines of defence that cyanobacteria use against UVR. EPS—exopolysaccharides, CAT—catalase, SOD—superoxide dismutase, GR—glutathione reductase, Car—carotenoids, MAAs—mycosporine-like amino acids, and Scy—scytonemin. -- International Journal of Molecular Sciences

Biophysics, Biosignatures & Paleobiology, Extremeophiles and Extreme Environments, Microbiology & Virology, Panspermia, Radiation, Status Report

Cyanobacteria Under UV Radiation: General Insights Into Stress Responses

by Keith CowingDecember 18, 2025December 18, 2025

One of the first organisms to appear on Earth was cyanobacteria, which carried out oxygenic photosynthesis.

This illustration shows Jezero Crater — the landing site of the Mars 2020 Perseverance rover. -- NASA.gov

Atmospheres, Climate, Weather, Biophysics, Biosignatures & Paleobiology, Desert Worlds, Habitable Zones, Icy Worlds, Mars, Microbiology & Virology, Origin & Evolution of Life, Radiation, Status Report

Modeling Photoprotection of Ultraviolet C Radiation by Ferric Ions and Implications for the Habitability of Ancient Martian Lakes

by Keith CowingDecember 10, 2025December 10, 2025

On Mars, the amount of ultraviolet C (UVC) radiation that reaches the surface is sufficiently deleterious for life as we know it.

Surface flux density observed and modelled. The m2F12-37-2.5 (dark green) and cF13-500-3 (light green) stellar atmosphere models are plotted at coefficients Xˆ 1=1 and Xˆ 2 = 1 (the theoretical assumption of the entire stellar surface exhibiting flaring activity). For AU Mic during a flare, the red solid and orange dashed lines show the fitted model spectrum at flare maximum using coefficients from the example fit (the flare data are stated in Table A.1 in Appendix A.2). The inverse H6 model at flare maximum, pre-flare and the ‘fiducial flare’ model from Loyd et al. (2018a) with a comparable ED is plotted as blue dash-dotted, light blue dashed, and purple dashed lines, respectively. Blackbody curves for 3850 K, 6000 K, 8000 K, and 10,000 K are included in black solid, dotted, dash-dotted and dashed lines. The panchromatic AU Mic flux from Feinstein et al. (2022) is plotted in light grey. Insets highlight the FUV (lower left) and TESS (lower right) wavelength ranges. -- astro-ph.SR

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Press Release, Radiation, Space Weather & Heliophysics

Young M Dwarfs Flare Activity Model: Towards Better Exoplanetary Atmospheric Characterisation

by Keith CowingDecember 8, 2025December 8, 2025

Context. Stellar flares can significantly influence the atmospheres and habitability of orbiting exoplanets, especially around young and active M dwarfs. Understanding the temporally and spectrally resolved activity of such stars […]

Scientists have captured the first detailed observations of how a superstorm compresses Earth’s plasmasphere and reveal why recovery took more than four days, affecting navigation and communication systems. CREDIT Institute for Space-Earth Environmental Research (ISEE), Nagoya University

Atmospheres, Climate, Weather, Habitable Zones, Magnetic Fields, Electromagnetism, bioelectricity,, Press Release, Radiation, Space Weather & Heliophysics

How Superstorm Gannon Squeezed Earth’s Plasmasphere To One-fifth Its Size

by Keith CowingNovember 21, 2025November 21, 2025

A geomagnetic superstorm is an extreme space weather event that occurs when the Sun releases massive amounts of energy and charged particles toward Earth. These storms are rare, occurring about […]