Williamsburg Torch Club 

At the April meeting of the Williamsburg Torch Club, member John Delano provided a great presentation on “NASA’s Search for Life Beyond the Earth.” Some of the discussion highlights are provided below.

Prior to 1995, scientists could only speculate on the existence of planets orbiting other stars. Is our solar system of eight planets unique? Or, are planets common elsewhere in the Milky Way galaxy? We now know that planets are not only common throughout our galaxy of more than 100 billion stars, but are considerably more diverse than our eight planets with respect to their orbits and sizes. While more than 5,600 planets have been observed so far orbiting “nearby” (i.e., within about 300 light years of Earth) stars, how many of them may be suitable to forming and sustaining life-as-we-know-it (i.e., carbon-based life)? Based on the measured sizes of those planets and their orbital distances from their stars, it appears that only a few percent of them have any potential for harboring life.

With the launch of the James Webb Space Telescope (JWST) in December 2021, the molecular compositions of atmospheres associated with some of those planets have been estimated. Those data are being carefully studied to assess whether any biosignatures exist in those atmospheric compositions that could reveal the presence of life on those distant worlds. Although a recent peer-reviewed article* suggested that dimethyl sulfide may be present in one planet’s atmosphere, which could indicate the presence of microbial life on that planet (K2-18b), more data are being collected with instruments onboard JWST to assess that result.

The search for life beyond the Earth has entered a new and exciting chapter! Stay tuned!

* Madhusudhan et al. (2023) Carbon-bearing molecules in a possible Hycean atmosphere. Astrophysical Journal Letters, 956, L13. (16pp)

Note: Another source for more information on this topic is Lisa Kaltenegger’s recent book, Alien Earths: The New Science of Planet Hunting in the Cosmos.