Dark Cloud Encounters
Tuesday, March 26, 2013
News Feature

Sometimes, science fiction is also science fact.

Katherine Wyman of the Harvard-Smithsonian Center for Astrophysics (CfA), began her Thursday night discussion, "Dark Cloud Encounters," by recalling a 2003 episode of the revived "Twilight Zone" television series called "Sunrise," during which the sun was blocked by a dark cloud, devastating the Earth's climate.

Such "clouds of gas and dust between stars" do exist, Wyman told a packed Phillips Auditorium, and they do indeed have the potential to alter the climate. Wyman spoke as part of the CfA's observatory nights, which invite the general public to hear about topics in astrophysics every third Thursday of the month.

Wyman has studied these "dark clouds" between stars (which Wyman also termed interstellar medium or "ISM") to learn how far away they are from Earth, as well as "how fast the clouds are moving, their temperature, and their density." Conducting research using the massive Harlan J. Smith Telescope ("it's larger than the Hubble Space Telescope," Wyman noted) at the Texas-based McDonald Observatory, Wyman meticulously observed how some of these dark clouds blocked the light coming from particular stars.

Wyman explained that the star called the sun gives off gas, wind, and particles, creating a "bubble" called the heliosphere. The heliosphere is dynamic, she said. "It can get bigger or smaller" depending on the density of the ISM surrounding it. The heliosphere shrinks with increases in density, something that the dark clouds can cause.