Atmospheres, Climate, Weather Archives

During the depths of a planetwide ice age, pockets of open ocean might have existed outside the tropics. HUYUE SONG

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Habitable Zones, Icy Worlds, Press Release

Snowball Earth Might Have Been Slushball Earth

by Keith CowingApril 8, 2023April 8, 2023

At least five ice ages have befallen Earth, including one 635 million years ago that created glaciers from pole to pole.

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Press Release, SETI & Technosignatures

A Newly Discovered Way That Earth’s Atmosphere Cleans Itself

by Keith CowingApril 8, 2023April 8, 2023

Editor’s note: One way to search for habitable – and possibly inhabited – worlds in our solar system and in other star systems is to examine planetary atmospheres for chemical […]

Two example cases comparing the outputs of one of the NN models with the corresponding TEA outputs. Left: Case where the NN’s predictions closely match the outputs of TEA, at a temperature of ∼1053 K, log C/H of -3.57, log N/H of -4.17, and log O/H of -3.31 over the full range of pressures considered in Table 1. Right: Case where the NN performs less accurately, at a temperature of ∼2112 K, M/H of 2.5, and C/O of 0.9 (log C/H of -0.956, log N/H of -1.556, and log O/H of -0.910). Despite the less accurate performance, the NN’s predictions are within an order of magnitude of the true values except for H2O, CO2, and HCN at the lowest pressures. Only abundances ≥ 10−15 are shown for clarity. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Status Report

Towards 3D Retrieval of Exoplanet Atmospheres: Assessing Thermochemical Equilibrium Estimation Methods

by Keith CowingApril 4, 2023April 4, 2023

Characterizing exoplanetary atmospheres via Bayesian retrievals requires assuming some chemistry model, such as thermochemical equilibrium or parameterized abundances. The higher-resolution data offered by upcoming telescopes enables more complex chemistry models […]

NUV (Near Ultra-Violet) luminosity versus star–planet separation. The UHZ (Ultraviolet Habitable zone, see §2) is defined by the inner (outer) boundary corresponding to the maximum (minimum) UV flux tolerable required) for life resilience (abiogenenesis, considering a specific prebiotic pathways). Three UHZ are shown corresponding to 100, 50 and 10% (as labelled) atmospheric transmission ( 𝑓 ), to the planet’s surface, of the UV flux at the top of the atmosphere. The planets of our sample (§3) selected for being in the CHZ (Circumstellar Habitable Zone) and having UV observations (thus providing 𝐿NUV) are shown by the circle symbols. The color coding corresponds to the 𝑇eff of their host stars (vertical color bar). The horizontal bar of each exoplanet shows the CHZ as derived by Kopparapu et al. (2013). The green shaded regions show the CHZ as derived through the 𝐿NUV ´ 𝑇eff correlation (§5). -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Press Release

The Ultraviolet Habitable Zone Of Exoplanets

by Keith CowingMarch 29, 2023March 29, 2023

The dozens of rocky exoplanets discovered in the Circumstellar Habitable Zone (CHZ) currently represent the most suitable places to host life as we know it outside the Solar System.

Relative contributions of major opacity sources in Y dwarf atmospheres. 400 K and 1 bar correspond to the photosphere for our clear, equilibrium model with Teff = 350, log10(g) = 4.25, and Z/Z = 1. CO is negligible at 400 K, but we have enhanced its abundance in the figure, as one might expect in cases of strong vertical mixing, in order to illustrate which wavelengths are affected. -- astro-ph.EP

Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

Self-consistent Models of Y Dwarf Atmospheres With Water Clouds And Disequilibrium Chemistry

by Keith CowingMarch 29, 2023

Y dwarfs are the coolest spectral class of brown dwarf. They have effective temperatures less than 500 K, with the coolest detection as low as ~250 K. Their spectra are […]

TRAPPIST-1 b F1500W measured flux and spectral models. The blackbody curves represent the measured TB = 503 K dayside temperature, the 508 K apparent dayside temperature predicted for zero heat redistribution and no internal heating, and Teq = 400 K temperature for isotropic redistribution of stellar heating. The flux expected in the upcoming observations in the MIRI F1280W filter is also shown assuming the planet emits like a TB = 503 K blackbody. The widths of the F1280W and F1500W markers represent their transmission half-amplitude bandpasses, and the vertical error bar of the F1500W point represents its 1σ uncertainty. Emergent spectra from 93 bar CO2 and 10 bar outgassed O2 with 0.5 bar CO2 atmospheres are also plotted [20, 33]. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, TRAPPIST-1

Thermal Emission From The Earth-sized Exoplanet TRAPPIST-1 b Using JWST

by Keith CowingMarch 27, 2023March 27, 2023

The TRAPPIST-1 system is remarkable for its seven planets that are similar in size, mass, density, and stellar heating to the rocky planets Venus, Earth, and Mars in our own […]

What do planets outside our solar system, or exoplanets, look like?

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release

A Catalogue Of Exoplanet Atmospheric Retrieval Codes

by Keith CowingMarch 25, 2023March 25, 2023

Exoplanet atmospheric retrieval is a computational technique widely used to infer properties of planetary atmospheres from remote spectroscopic observations.

Astronomy & Telescopes, Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release

Silicate Cloud Features Observed By Webb On Exoplanet VHS 1256 b

by Keith CowingMarch 22, 2023March 22, 2023

Researchers observing with the NASA/ESA/CSA James Webb Space Telescope have pinpointed silicate cloud features in a distant planet’s atmosphere.

The extraterrestrial processes responsible for influencing the diversity of life forms are usually invisible to the human eye. The Milky Way is where large stars explode, leading to supernova remnants whose shock fronts accelerate cosmic ray particles to high energies. Cosmic rays find their way to the solar system, where some collide with the atmosphere producing cascades of secondary particles which ionize the atmosphere. Ions influence the formation of clouds which ultimately affect climate. Therefore, changes in supernova activity change climate, which is responsible for mixing and transporting life's essential nutrients to the ecosystems (Illustration: Henrik: Svensmark, DTU Space).

Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Extinction events, Fossils & Paleontology, Press Release

A Persistent Influence Of Supernovae On Our Planet’s Biodiversity

by Keith CowingMarch 21, 2023March 21, 2023

Extensive studies of the fossil record have shown that the diversity of life forms has varied significantly over geological time, and a fundamental question of evolutionary biology is which processes […]