Humans have likely always looked at the sky and wondered if we are alone in the universe. From the classical Roman messenger god Mercury to the angelic hosts of the Abrahamic religions, ancient belief systems often referred to gods and other visitors as omnipotent beings capable of traversing heaven and earth.
As technology improved and enhanced humanity’s understanding of the universe, the habitability of neighboring planets became a legitimate scientific endeavor. Natural geographic features of Mars were (incorrectly) interpreted as intentionally engineered, and the idea of intelligent Martians and Venusians populated science fiction. Our fleet of robotic investigators throughout the solar system can now confirm that no advanced species constructed canals on Mars, and that intelligent life as we know it could not survive on these inhospitable worlds. This insight has led us to look deeper into the history of our own planet to discover what the origins of life may be.
Reel back a few hundred million years to the Cambrian Explosion, when life expanded from single-celled to multicellular organisms, complex life. The fossil record shows that this began in the oceans, with large populations of phytoplankton gobbling up abundant carbon and using sunlight as energy to convert up to half the oxygen in our atmosphere. One byproduct of this process is the compound dimethyl sulfide, only known to be naturally produced through this process.
Astrobiologists use many different factors in the search for extraterrestrial life. Earthlike conditions for habitability have led us to define the Goldilocks zone, where a planet orbits its star at a distance that makes it neither too hot nor too cold, but “just right” for liquid water to exist. A breathable atmosphere like ours would optimally be composed of about 3:1 nitrogen to oxygen, with trace amounts of other elements and compounds such as carbon dioxide, methane and, you guessed it, dimethyl sulfide.
The James Webb Space Telescope’s extremely sensitive instruments can measure the atmospheres of distant worlds by studying light that has passed through them. In the constellation Leo, 124 light years from us, the exoplanet K2-18b just happens to be in this Goldilocks zone around a red-dwarf star about eight times the mass of Earth. Following up on observations made by the Kepler and Hubble telescopes, JWST data indicates the atmosphere is likely made up of hydrogen, carbon, methane and dimethyl sulfide. If this is confirmed it’s possible that a form of early photosynthesis is active in the oceans of this alien world.
As Leo moves to the southwest through the spring, Mars will enter the constellation later in May. While observing the Martian “canals” from your own backyard, your field of view may well include distant worlds teeming with the earliest forms of microbial life.
If you would like to learn more about the sky, telescopes, or socialize with other amateur astronomers, visit us at prescottastronomyclub.org or Facebook @PrescottAstronomyClub to find the next star party, Star Talk, or event.
Adam England is the owner of Manzanita Financial and moonlights as an amateur astronomer, writer, and interplanetary conquest consultant. Follow his rants and exploits on Twitter @AZSalesman or at Facebook.com/insuredbyadam.
