Saturn's atmosphere, infrared Cassini image. Saturn's internal thermal glow is seen to reveal a regular pattern in the planet's deep cloud system. The white areas are clearings in the cloudy atmosphere, through which more of the planet's internal thermal glow is seen. Each is located around 3.5 degrees longitude away from its neighbour and this is the first time such regular cloud openings have been seen. The regularity may indicate that a large planetary wave is occurring on Saturn, but more observations are needed to fully understand this meteorological phenomenon. Saturn's rings can also be seen behind the planet (turquoise). Image taken by NASA's Cassini spacecraft on 27th April 2006.