February 2017

The classical habitable zone is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N2-CO2-H2O habitable zone (HZ) extends out to nearly 1.7 AU in our Solar System, beyond which condensation and scattering by CO2 outstrips its greenhouse capacity.

We present results of simulations of the climate of the newly discovered planet Proxima Centauri B, performed using the Met Office Unified Model (UM). We examine the responses of both an `Earth-like' atmosphere and simplified nitrogen and trace carbon dioxide atmosphere to the radiation likely received by Proxima Centauri B.

Titan is the only moon with a substantial atmosphere, the only other thick N2 atmosphere besides Earth's, the site of extraordinarily complex atmospheric chemistry that far surpasses any other solar system atmosphere, and the only other solar system body with stable liquid currently on its surface.

A new study led by The Australian National University (ANU) has found seawater cycles throughout the Earth's interior down to 2,900 km (1,800 miles), much deeper than previously thought, reopening questions about how the atmosphere and oceans formed.

Rocky planets orbiting M-dwarf stars in the habitable zone tend to be driven to synchronous rotation by tidal dissipation, potentially causing difficulties for maintaining a habitable climate on the planet.

There exists a positive correlation between orbital eccentricity and the average stellar flux that planets receive from their parent star. Often, though, it is assumed that the average equilibrium temperature would correspondingly increase with eccentricity.

With the discovery of rocky planets in the temperate habitable zone (HZ) of the close-by cool star TRAPPIST-1 the question of whether such planets could also harbour life arises.

NASA's Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water.

NASA's Dawn mission has found evidence for organic material on Ceres, a dwarf planet and the largest body in the main asteroid belt between Mars and Jupiter.

Recent 60Fe results have suggested that the estimated distances of supernovae in the last few million years should be reduced from 100 pc to 50 pc. Two events or series of events are suggested, one about 2.7 million years to 1.7 million years ago, and another may at 6.5 to 8.7 million years ago.

We address the important question of whether the newly discovered exoplanet, Proxima Centauri b (PCb), is capable of retaining an atmosphere over long periods of time. This is done by adapting a sophisticated multi-species MHD model originally developed for Venus and Mars, and computing the ion escape losses from PCb.

In a long-term experiment on the International Space Station, Fraunhofer researchers studied how the extreme conditions in space affect algae. Fraunhofer conducted this experiment in close cooperation with German and international partners. Research findings could benefit industrial applications and perhaps a mission to Mars.

Conventional definitions of habitability require abundant liquid surface water to exist continuously over geologic timescales. Water in each of its thermodynamic phases interacts with solar and thermal radiation and is the cause for strong climatic feedbacks.

Hazes are common in known planet atmospheres, and geochemical evidence suggests early Earth occasionally supported an organic haze with significant environmental and spectral consequences. The UV spectrum of the parent star drives organic haze formation through methane photochemistry.

Many scientists believe the Earth was dry when it first formed, and that the building blocks for life on our planet -- carbon, nitrogen and water -- appeared only later as a result of collisions with other objects in our solar system that had those elements.

For astronomers trying to understand which distant planets might have habitable conditions, the role of atmospheric haze has been hazy.

The search for life beyond Earth starts in habitable zones, the regions around stars where conditions could potentially allow liquid water - which is essential for life as we know it - to pool on a planet's surface.

Regulations governing METI are weak or non-existent. Post-detection SETI protocols are non-binding and too general. Vastly increased SETI capabilities, Chinese involvement in the field, and an intensified effort by METI-ists to initiate radio transmissions to the stars are among reasons cited for urgency in addressing the question of appropriate regulations. Recommendations include regulations at the agency level and laws at the national level as well as international treaties and oversight.

Ocean-atmosphere chemistry on Earth has undergone dramatic evolutionary changes through its long history, with potentially significant ramifications for the emergence and long-term stability of atmospheric biosignatures.

Researchers have identified traces of what they believe is the earliest known prehistoric ancestor of humans - a microscopic, bag-like sea creature, which lived about 540 million years ago.

Mars was characterized by cataclysmic groundwater-sourced surface flooding that formed large outflow channels and that may have altered the climate for extensive periods during the Hesperian era. In particular, it has been speculated that such events could have induced significant rainfall and caused the formation of late-stage valley networks.

Rampino & Caldeira (2015) carry out a circular spectral analysis (CSA) of the terrestrial impact cratering record over the past 260 million years (Ma), and suggest a ~26 Ma periodicity of impact events. For some of the impacts in that analysis, new accurate and high-precision ("robust"; 2SE<2%) 40Ar-39Ar ages have recently been published, resulting in significant age shifts.

Photosynthesis, creating oxygen and carbohydrates such as glucose from solar energy, water, and CO2, is indispensable for many species on this planet. However, it is unclear exactly how or when organisms evolved the ability to photosynthesize. These questions have fascinated scientists for a long time.