As TESS surveys a large part of our sky and tries to capture some information about other suns and their exoplanets–we might get some idea of how alone we living critters are in this huge loaded, but not crowded, universe.
A basic review–”Exoplanets” by Michael Summers and James Trefil (Washington D.C., Smithsonian books, 2017)– reminds us that solar systems probably form in stages. During planet formation dust and debris either gets “…absorbed or thrown out of the system…,” then gravity takes over in a “…game of cosmic billiards…”. Theory suggests that a dozen “man-sized objects” were thrown out of our solar system during a late
stage. Some of the ejected “bodies” ended up orbiting the galaxy’s center as “rogue planets.”
Early estimates (for rogue planets in our Milky Way that were made before 2011) were huge. It was first thought that Jupiter-sized rogue stars, those without a sun, would outnumber the stars in our galaxy. But Sky and Telesope August 2017 by Monica Young noted that the guess from data taken by OGLE between 2010 and 2015 is more like 75 billion, not a trillion.
OGLE the Optical Gravitational Lensing Experiment has some capacity for finding these objects that don’t have a planetary companion. Nature Astronomy reported that later microlensing events suggested that Jupiter-size rogue planets occur less than one for every star, no more than 75 billion, not one trillion as early estimated. Six of these free-floating planets were near Earth-size. WFIRST and Euclid will soon be able to find these microlensing events on a finer scale.
Could any of these objects without a companion sun harbor life? Does life have to exist on a planet’s surface? We now know of many of Earth’s life forms that live deep in rocks or in the ocean and near ocean vents. Energy for life could be supplied from billions of years of cooling off from the first formation of a planet or the radioactive display of its elements or tidal heating of subsurface oceans, not just from radiation
from a star, as we have here on Earth.
Finding such rogue planets is very difficult, even as we increase our sensitivity of our infrared detectors and use gravitational lensing suggested by the “general theory of relativity,” which has also been used to detect huge concentrations of dark matter. To detect rogue planets, astronomers have used the chance alignment of this monitoring
technique to pick up the areas or rings created by the rogue planet acting as a “kind of lens, focusing the light from [a] distant star.’” Chance alignments of rogue planets and passing stars provide such a ring of light.
The book here quoted,”Exoplanets,” explains in detail how such rogue planets and even their moons could have liquid surfaces or subice oceans, hence life. The probability for life elsewhere goes up with such speculation on rogue planets, but our chance of finding life goes down with the realization that the surface of such rogue planets would always be dark. Any life would need sight using infrared radiation, as do
Earth’s pit vipers.
Meanwhile, we’ll keep a watch on what TESS finds on exoplanets, and what they tell us about possible planetary environments that might sustain life. So far we are learning how extremely varied planetary systems can be, and how few are as lucky as our Earth, which has had many chance encounters that have made our existence possible. See last month’s article.
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- 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