Saturn’s North Pole

north-poleThese two natural color images taken by the Cassini spacecraft show how Saturn’s north polar region has changed between 2012 and 2016. The color change is thought to be an effect of Saturn’s seasons. It suggested that the change from a bluish color to a more golden hue is due to the increased production of smog in the atmosphere as the north pole approaches summer solstice in May, 2017.

The hexagon, Saturn’s six-sided jetstream, may act as a barrier preventing haze particles produced outside it from entering. If that’s the case, the polar atmosphere could have become clear of aerosols produced by photochemical reactions, reactions caused by sunlight, during the winter. After Saturn’s equinox in August, 2009, the north pole polar has been in continuous sunshine, and smog aerosols are being produced inside the hexagon, making the polar atmosphere appear hazy.

Image Credit: NASA

In Daylight on the Night Side

rings-in-daylightThe Cassini spacecraft looked down at the rings of Saturn from above the planet’s nightside to take this picture. The darkened globe of Saturn is on the lower right, along with the shadow it casts across the rings. Even on the planet’s night side, part of the rings remain in sunlight, and they reflect sunlight back onto the night side of the planet, making it appear brighter than it would otherwise appear.

Saturn’s small moon Prometheus ( 86 km across) is faintly visible as a speck near upper left. Earlier in the planet’s year, Saturn’s shadow was once long enough to stretch to the orbit of Prometheus, but as northern summer solstice approaches, the shadow no longer reaches that far. Prometheus won’t be in the planet’s shadow until the progression of the seasons again causes the shadow to lengthen.

Image Credit: NASA

Shaping Dione

Dione_TectonicsThis image of Saturn’s moon Dione shows a mixture of features: bright, linear features showing evidence of tectonic movant and impact craters. The tectonic features reveal that Dione has been heated and cooled since its formation, and scientists use those as clues to piece together the moon’s past. The impact craters are evidence of external debris striking the surface and tell about the environment in which the moon has existed over its history.

Image Credit: NASA

Broken Rings?

broken ringsThat’s not a gap in Saturn’s rings. It’s the planet’s shadow. During most of Saturn’s year, the planet’s shadow extends well beyond the edge of the rings.  However, with summer solstice fast approaching, the Sun is higher in Saturn’s sky and most of Saturn’s A ring is completely shadow-free.

Saturn’s large moon Titan, its northern hemisphere in sunlight of late spring, hangs above the rings.

Image Credit: NASA