Cosmic Thursdays, a series of free and public talks about astronomy-related topics, returned on Thursday, October 15 with a lecture entitled “Alternative Earths: What our planet’s history may tell us about life in the Universe.” The talk was given by Timothy Lyons, a professor in the earth sciences department at UCR who earned his Ph.D in geology geochemistry from Yale University.
Lyon began the lecture by discussing the recent revelation of liquid water on Mars. Many of the results display linea, which are downslope streaks assumed to be liquid water. “There’s quite a bit of debate about how these things are generated. They’re associated with salts, flurate, other compounds that are known to be microscopic,” Lyons explained. Many are hoping that the liquid water is coming from the subsurface, which would allow fluids to flow seasonally. “I’d say the jury is still out on that but stay tuned because these kinds of things are coming fast and furiously. We’re launching soon for another rover in 2020,” Lyons stated.
Other places also explored for liquid water are icy moons. Both Europa, Jupiter’s moon, and Saturn’s moon Enceladus are candidates. “There could be subsurface liquid oceans that would be beneath the icy crust,” Lyons said. In order for the water to be in liquid form, the moon would need to absorb heat generated by the planet it orbits, which is possible. The Europa fly-by has been approved and will launch in the next decade. The mission is hoping to capture one of the plumes containing water erupting from the icy crust.
The celestial bodies Lyons is most excited to find liquid water on are extra-solar planets, also known as exoplanets. These planets exist outside of our solar system. The first exoplanet was discovered in 1992 and since then, Kepler has discovered over 4,000 exoplanet candidates. One way they are detected is by using the transit method, which consists of keeping a telescope like Kepler directed at a star and waiting for the light to dim, signifying that a planet has passed by. “It’s easier to identify planets that are large. It’s also easier to identify planets that are close to their stars because they transit across their stars more frequently,” he explained. “There could be as many as 40 billion earth-sized planets orbiting in the habitable zones of sun-like stars or red dwarfs within the Milky Way.”
Finding planets in the habitable “Goldilocks” zone is promising, but Lyon suggested that it’s impossible to know if the “ingredients of life” are identical for all places around the universe. “You have to keep an open mind and you have to think in a theoretical space. There are certainly other possibilities,” Lyons stated. However, according to Lyons finding intelligent life won’t happen any time soon, and contrary to popular belief, scientists aren’t looking for it. “What we’re really doing is looking for signs of microbial activity. I hate to say it but we’re not going to find a footprint,” Lyons explained.
The talk concluded with a Q-and-A in which Lyons was able to explain more about Earth, as well as talk about the possibility of finding similar planets elsewhere to curious attendees. The next talk in the Cosmic Thursdays series will discuss tracking the evolution of life using ancient lipid biomarkers preserved in rocks and petroleum; it will take place on November 12.