How close can a sun be to its orbiting planets before it is not habitable? The answer depends on its atmosphere and the amount of water on the planet, but also where that water is. If water is at the planet’s poles, even though there be less than 10% of Earth’s water, a planet can be habitable.
Also, atmospheric coating can insulate a planet, preserving water so that it can be habitable, unless it becomes too warm. A runaway greenhouse cycle occurs if there is too much water. We have a lot here. That’s why we on Earth have such narrow habitable zones. Land planets have a wider habitable zone than we do.
The AGU,s Earth and Space Science News recently reported the work of T. Kodema, an astrophysicist at the University of Bordeaux, France. He has determined how close a planet can be to its sun before a runaway
greenhouse effect occurs, causing a planet’s water to disappear. “Land planets with dryer equators“ can live closer to their suns. If water is nearer to the poles, a planet can maintain its water closer to its sun.
Good news: AGU (American Geophysical Union) has announced a partnership (funded by Kavli Foundation) with the AAS (American Astronomical Society), to bring together relevant researchers from around the world–astronomers, planetary scientists and geophysicists. They will hold special meetings annually and hold conferences and workshops organized by a joint steering committee.
They will study the 3000 exoplanets identified in the 2000 planetary systems found to date–”several dozen” of which are in the habitable zone with liquid water. They will focus on physical clues, atmospheric chemistry, and rotational and orbital dynamics. Check out reports from the fall 2018 and summer 2019 exoplanet conferences.
More details next month. Books are being written about our exoplanet neighbors.
Author of The Archives of Varok
The View Beyond Earth (Book 1.)
The Webs of Varok (Book 2.)
Nautilus Silver Award 2013 YA
ForeWord IBPA finalist 2012 adult SF
The Alien Effect (Book 3.)
An Alien’s Quest (Book 4. Released Nov.21, 2016)
Excerpts, Synopses, Reviews, On Writing, Characters and More-
Reviews of significant books- http://www.goodreads.com/Cary_Neeper
How the Hen House Turns- http://www.ladailypost.com
Complexity, Bio, Bibliography and Links- http://caryneeper.com
Astrobiology- http://astronaut.com search:Who’s Out There