Exoplanets and Extraterrestrials
By Justin Isherwood
In 1988 came the first detection of an exoplanet. To that juncture, exoplanets had been the grist for science fiction and screen writers. Luke Skywalker called Tatooine home, this in a galaxy far away. For 150 years we have been charmed on this fiction of extraterrestrial life with no evidence beyond our solar system that other earths existed.
H.G. Wells in “War of the Worlds” probably deserves credit for the genre of alien life fiction though any kid around a campfire on a dark night, looking at the star-cobbled sky probably knows the same imaginative force. It was Anaxagoras who, circa 450 B.C., theorized that stars were actual suns themselves not just some decorative lanterns hanging from a vaulted ceiling.
It wasn’t until the mid-17th Century that Giordano Bruno suggesting that stars were suns became a strong pulse in the philosophical and scientific community. Bruno was executed and burned as a heretic for his extra-terrestrial view. About this same time, Galileo was imprisoned, if a more casual house-arrest. Concurrent was Christiaan Huygens living in free Protestant Holland who estimated the distance to Sirius based on its relative brightness. This standard candle method is still used by astronomers, if we now know there are different kinds of candles.
In 1718, Edmund Halley discovered the proper motion of stars that Biblical teaching held as immoveable, as explains why the night sky in Genesis is called the firmament. In 1881, Bessel used parallax trigonometry to determine star distance, at which point stars as distant suns became a concrete scientific fact.
Perhaps it is that kids around campfires have always known stars were all suns, and there has been an alien invasion story in our mental midst since time immemorial. It is interesting that aliens don’t show up in world literature including the Bible and the Bhagavad Gita, whereas aliens are omnipresent in modern literature and movies. The difference being that when the general public came to think of stars as suns like our own, those suns had planets and peoples, some looking for colonies.
“War of the Worlds,” in 1898 by H.G. Wells, changed world literature; it also changed our scientific sense of what’s out there and the inquiry that goes with it. The basic message being, “There could be somebody out there.” Now thousands of movie versions later, this alien potential remains the touchstone of script writers, only to mention “Star Wars 8” is due out in December.
To date, there are 4,496 sighted exoplanets, 3,500 confirmed, 2,613 solar systems with 363 have terrestrial planets, meaning dirt versus gas.
In the 1970s, the astronomical estimate for Earth-like planets in our Milky Way galaxy was on the order of 10,000 with “perhaps life potential.” This estimate always comes with the added caveat for planets having intelligent life versus the ordinary life. Meaning ants, honey bees, wasps, sea turtles and barn swallows don’t count as intelligent life, to suggest there might be a difference of opinion on this assumption.
The current estimate of the 200 billion stars in the Milky Way neighborhood, 11 billion are potentially habitable; the number goes to 20 billion when red dwarf stars are included. The current estimate is that one in five stars have Earth-size planets in the habitable zone. Knowing that changes the scenery for any kid looking at the night sky, better the odds someone or something is looking back wondering the self-same question.
We have yet to crack biologically if not necessarily philosophically the habitable zone concept for planetary life. Life in our experience requires liquid water, an atmosphere, preferably oxygen, then there’s the protective magnetic field, carbon in abundance, no extreme temperatures. To wonder if the life process can form beyond these habitable zone precepts, beyond our radiation constraints, without water.
To ask what are the odds of life figuring out a way to happen, using whatever chemistry is at hand to create the reproductive memory we call life, perhaps all those Jovian planets of ammonia and methane are not so out of bounds for “life.” When what is really necessary is a long-term, stable environment on the order of billions of years, only to await the chance of some odd chemical intrigue.
As a farmer, I plow soils that contain complex, innumerable life systems, literally thousands of life forms, most of which are unseen, and from any pedestrian point of view, unknown. Does the cosmos have a similar micro flora and fauna?
Of exoplanets now known, that vast majority are classified as Neptunian or Jovian worlds compared to the number of Terrain worlds such as our Earth.
K. Wagner in “Science” August 2016 described the solar system identified as HD41004, a small sun system with a planet 2.5 times that of Jupiter on an Earth-radius orbit. A second star is orbiting at a Uranus distance in turn orbited by a sub-stellar object 20 times the mass of Jupiter, as begins to sound a touch complicated.
To wonder if there is a farm kid on that planet, and wonder what they think is normal.