Water in Extrasolar Planets and Implications for Habitability
49
Citation
154
Reference
10
Related Paper
Citation Trend
Keywords:
Habitability
Planetary habitability
For life-forms like us, the most important feature of Earth is its habitability. Understanding habitability and using that knowledge to locate the nearest habitable planet may be crucial for our survival as a species. During the past decade, expectations that the universe could be filled with habitable planets have been bolstered by the increasingly large overlap between terrestrial environments known to harbor life and the variety of environments on newly detected rocky exoplanets. The inhabited and uninhabited regions on Earth tell us that temperature and the presence of water are the main constraints that can be used in a habitability classification scheme for rocky planets. Our compilation and review of recent exoplanet detections suggests that the fraction of stars with planets is ∼100%, and that the fraction with rocky planets may be comparably large. We review extensions to the circumstellar habitable zone (HZ), including an abiogenesis habitable zone and the galactic habitable zone.
Habitability
Planetary habitability
Kepler-69c
Cite
Citations (55)
Abstract Earth’s climate has remained continuously habitable throughout 3 or 4 billion years. This presents a puzzle (the ‘habitability problem’) because loss of habitability appears to have been more likely. Solar luminosity has increased by 30% over this time, which would, if not counteracted, have caused sterility. Furthermore, Earth’s climate is precariously balanced, potentially able to deteriorate to deep-frozen conditions within as little as 1 million years. Here I present results from a novel simulation in which thousands of planets were assigned randomly generated climate feedbacks. Each planetary set-up was tested to see if it remained habitable over a period of 3 billion years. The conventional view attributes Earth’s extended habitability solely to stabilising mechanisms. The simulation results shown here reveal instead that chance also plays a role in habitability outcomes. Earth’s long-lasting habitability was therefore most likely a contingent rather than an inevitable outcome.
Habitability
Planetary habitability
Cite
Citations (29)