Autumn on Titan
Earth isn't the only one in the solar system going through a change of seasons. NASA's Cassini mission recently took this image of an ice cloud forming on Titan's south pole. Scientists have observed a similar ice cloud on the Saturn moon's north pole, but never in the south before. The cloud "is the latest sign that the change of seasons is setting off a cascade of radical changes in the atmosphere of Saturn's largest moon," according to yesterday's press release. Each season on Titan lasts about seven-and-a-half years, and astronomers first started to notice the change in the south pole in 2012. What's even more exciting than witnessing the seasonal change is determining what makes up the ice.
So far, the identity of the ice in these clouds has eluded scientists, though they have ruled out simple chemicals, such as methane, ethane, and hydrogen cyanide, which are typically associated with Titan. One possibility is that "species X," as some team members call the ice, could be a mixture of organic compounds.
Credit: NASA/JPL-Caltech/Space Science Institute