It may be the most unusual feature in the solar system. First spotted in the 1980s by NASA’s two Voyager spacecraft, this gigantic hexagonal cloud formation sits atop Saturn’s north pole. The new image–taken during Saturn’s long polar night by the Cassini spacecraft last October and released on 27 March–clearly shows the 25,000-kilometer-wide feature, big enough to hold four Earths. Even stranger, the hexagon apparently rotates much more slowly than the rest of the planet, while Saturn’s clouds swirl around it. So far, scientists are unsure what causes the phenomenon: possibly deep thermal cloud patterns or something related to the planet’s magnetic field. (Photo: NASA/JPL/University of Arizona)
