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Carbon dioxide (CO2) increase has been well documented, and global net primary production is of importance to a variety of ecological topics. Since CO2 increases primary production in laboratory experiments, the global effects of increasing…
Volcanism is a major and long-term source of volatile elements such as C and H to Earth's atmosphere, likely has been to Venus's atmosphere, and may be for exoplanets. Models simulating volcanic growth of atmospheres often make one of two…
The original hypothesis about Three-stage origin of life (TOL) on the Earth is developed and discussed. The role of the temperature factor in life origin is considered. It is supposed, that three stages of abiogenesis (DNA world, RNA world…
The formation of the Earth's core is a consequence of planetary accretion and processes in the Earth's interior. The mechanical process of planetary differentiation is likely to occur in large, if not global, magma oceans created by the…
On the Earth, photosynthetic organisms are responsible for the production of virtually all of the oxygen in the atmosphere. On the land, vegetation reflects in the visible, leading to a red edge that developed about 450 Myr ago and has been…
Oxygenic photosynthesis is the most important biochemical process in Earth biosphere and likely very common on other habitable terrestrial planets, given the general availability of its input chemical ingredients and of light as source of…
Ozone (O3) is a triatomic molecule of central importance in the chemistry and physics of the Earth's and other planetary atmospheres. Beyond its environmental significance, a detailed understanding of the electronic structure and ionization…
Complex organics are now commonly found in meteorites, comets, asteroids, planetary satellites, and interplanetary dust particles. The chemical composition and possible origin of these organics are presented. Specifically, we discuss the…
Sulfur gases are common components in the volcanic and biological emission on Earth, and are expected to be important input gases for atmospheres on terrestrial exoplanets. We study the atmospheric composition and the spectra of terrestrial…
The origin of life on Earth would benefit from a prebiotic atmosphere that produced nitriles, like HCN, which enable ribonucleotide synthesis. However, geochemical evidence suggests that Hadean air was relatively oxidizing with negligible…
The optical filaments found in many cooling flows in galaxy clusters consist of low density ($\sim 10^3 \pcc$) cool ($\sim 10^3$ K) gas surrounded by significant amounts of cosmic-ray and magnetic-field energy. Their spectra show…
Given the central role of carbon in the chemistry of life, it is a fundamental question as to how carbon is supplied to the Earth, in what form and when. We provide an accounting of carbon found in solar system bodies, in particular a…
Earth-like planets orbiting M-dwarfs are prominent future targets when searching for life outside the solar system. We apply our newly developed Coupled Atmosphere Biogeochemistry model to investigate the coupling between the biosphere,…
The disequilibrium combination of abundant methane and carbon dioxide has been proposed as a promising exoplanet biosignature that is readily detectable with upcoming telescopes such as the James Webb Space Telescope. However, few studies…
It is not currently possible to create a living organism ab initio due to the overwhelming complexity of biological systems. In fact, the origin of life mechanism, this being how biological organisms form from non-living matter, is unknown.…
(Abridged) Exoplanet atmospheres are thought be built up from accretion of gas as well as pebbles and planetesimals in the midplanes of planet-forming disks. The chemical composition of this material is usually assumed to be unchanged…
The near-term capability to characterize terrestrial exoplanet atmospheres may bring us closer to discovering alien life through atmospheric data. However, remotely detectable candidate biosignature gases are subject to false positive…
We review some basic issues of the life-prescribed development of the Earth's system and the Earth's atmosphere and discourse the unity of Earth's type of life in physical and transcendental divisions. In physical division, we exemplify and…
Methane has been proposed as an exoplanet biosignature. Imminent observations with the James Webb Space Telescope may enable methane detections on potentially habitable exoplanets, so it is essential to assess in what planetary contexts…
We present a theoretical analysis of formation and kinetics of hot OH molecules in the upper atmosphere of Mars produced in reactions of thermal molecular hydrogen and energetic oxygen atoms. Two major sources of energetic O considered are…