Titan is pretty Earth-like. It's got methane cycles akin to our planet's water cycle, and it's inclined by about 27 degrees, similar to the Earth. That incline means Titan has season like Earth does, and scientists have collected 30 years of data about the moon's seasons, the equivalent of a full year. Turns out, Titan's seasons are another similarity the moon has with our own planet.
As the seasons turn on Titan, we see changes in atmospheric temperatures, chemical composition, and circulation patterns. Particularly at the poles, where hydrocarbon lakes form around the north during winter's colder temperatures, and a haze that lessens as temperatures warm in the spring. It's a surprising find; no one expected to see such rapid changes, especially in the deeper layers of the atmosphere. That said, rapid is a relative term, as seasons on Titan last seven and a half Earth years.
It turns out that the main cause is solar radiation, the dominant energy source affecting Titan's atmosphere. Solar radiation breaks the nitrogen and methane in the atmosphere into more complex molecules like ethane.
Titan, with conditions similar to those on our own planet in terms of its climate, meteorology and astrobiology, is a really interesting place to study. It's also amazing that the sun has such a strong effect on a body as far as 942 million miles away from us.
In a press release, Dr. Athena Coustenis of France's Paris-Meudon Observatory stressed why Titan is such a good candidate for study: "Titan is the best opportunity we have to study conditions very similar to our own planet in terms of climate, meteorology and astrobiology and at the same time a unique world on its own, a paradise for exploring new geological, atmospheric and internal processes."