First a quick review of the “Firsts” that NASA has reported. Planet Hunter found the first “Earth-size Habitable Zone World.” Their TESS mission found the first “World With Two Stars,” and their Hubble
found “Water Vapor on an Exoplanet in a Habitable Zone.” Keep a watch on TOI 700d, TOI 1338 b and K2-a8b.
TOI 700d is in its sun’s habitable zone, 20% larger than Earth and tidally locked to its star. It is probably rocky. TOI 1338a orbits two stars and is 6.9 times larger than Earth with a wobbly orbit around its sun, which is 10% larger than Earth’s.K2-18b is in its star’s habitable zone, but it may have a nasty radiation environments. It is huge (8 times the size of Earth) and may not be “terrestrial” like Earth. Hopefully the James Webb Space Telescope will be able to decide if its atmosphere includes nitrogen and methane.
The problem for anyone hoping to move to any one of the three “firsts” is that they are all 100 and more light-years from Earth. Again, it looks like we’d better stay here on lucky planet Earth.
The more we look out, enjoying our life-supporting sun with its gorgeous emergence every morning (somewhere on Earth–see photo attached), the less we see of others. Most exoplanets found so far are too dry, too
hot, too close, too far, too big, too small or too something else. It makes me wonder how alone and how lucky Earth was to keep its life-supporting water so long. The list of happy accidents that supported life here have been beautifully detailed by experts
Of course, water and life won’t last forever here. The sun will expand, and engulf Mercury as a red giant, then Venus. Maybe Jupiter and its Europa will then be able to house life, or maybe Saturn’s Enceladus. Earth and Mars will be too hot in a billion years.
The universe is very large. There are an astounding number of galaxies beyond ours and many suns in our huge galaxy,. So far they seem to be very different, with variable planets, most too hot, too close to their sun, or too dry to host life. So far, apparently, there is nothing very close to Earth that could house and feed life comfortably.
Mars may have had water for its first millions of years, but our sun eventually dried it out, and its magnetic field went away. Venus was once wetter and more temperate than it is now, until the sun grew hotter, according to Nova’s “The Planet’s Inner Worlds” KQED, circa January 2020. Magellan’s radar has seen evidence of volcanism there and a runaway greenhouse.
The problem for life elsewhere in our solar system has been too much heat to keep water handy for life. Runaway greenhouse effects are tough on life, which requires water for anything similar to life as we know it.
In James Trefil and Michael Simmes book “Imagined Life” the authors point out that our physics is reliable. Careful selection probably drives evolution, but not even a scan is required if there are hydrothermal vents driven by heat from radioactive decay in an exoplanet’s core. Of course, any life might be very different from Earth’s–given such physical challenges.
If we knew just exactly where Earth’s water came from originally, we might have a better idea of what could be happening elsewhere. Did asteroids bring water here? Or did water come after Earth cooled?
Probably from comets? Heavy water content suggests it came late. Does Earth’s mantle hold a lot of water? Check out November 2019 Discover.
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.)
Excerpts, Synopses, Reviews, On Writing, Characters and More-
Reviews of significant books- www.goodreads.com/Cary_Neeper
How the Hen House Turns- www.ladailypost.com
Complexity, Bio, Bibliography and Links- caryneeper.com
Astrobiology- astronaut.com search:Who’s Out There