On Friday the 15th September, the Cassini space probe fell into the dense clouds of Saturn – the planet it had spent 13 years recording and examining. It was a poignant moment for the international community of astronomers – and not just those directly involved – thanks to the masses of data the probe sent back and will be analysed over the next 3-4 years. Thanks to Cassini, we have learnt so much about our solar system’s second largest planetary body made famous by its iconic rings. Here’s just some of what we know:
Cassini Taught Us about Saturn’s Polar Storms
As planets spin on their axis, polar vortex storms are common – this is the case on Earth too. With a planet the size of Saturn the storms have such wild power that it’s hard to imagine what it might be like to watch it up close. Cassini got closer than ever before to the polar storms, transmitting masses of data about the dense and swirling clouds that envelope Saturn. The polar storms are like immense hurricanes that could swallow up our home planet many times over.
Cassini Taught Us about Saturn’s Rings
It has long been understood that the planetary rings common to some large planets are the result of smaller bodies breaking up in the atmosphere and spreading out into an orbit. Saturn is no different. What Cassini did teach us this time is that the rings around Saturn are wild and not uniform. The chunks that form the orbit of the F Ring (the outermost ring) vary in size from half a mile wide to 100 miles wide. We also discovered that this F Ring has two moons closely orbiting along with it – small moons of Pandora and Prometheus.
Cassini Taught Us about Saturn’s Moons
While Cassini’s mission to Saturn revealed masses of data about the planet, part of the project focused on Saturn’s intriguing series of moons, particularly Enceladus and Titan. These two bodies are known to contain liquid water – the former beneath its icy surface and the latter believed to contain vast caverns of water (as well as liquid methane on the surface) beneath its dense clouds. These, just two of Saturn’s 62 moons, have come in for particular interest. Cassini was also responsible for increasing the number of discovered moons from 13 to 62, 53 of which have been named.
Cassini Showed Us That Titan has Plastic in its Atmosphere
Perhaps one of the most surprising discoveries of the Cassini mission concerns the data sent back from Titan. Not only is there evidence of liquid methane, complex geology, weather systems, and underground lakes of water, but also traces of plastic in the atmosphere. Most interesting, the type of plastic was the type that we use for food storage – propylene. It exists in a simpler format but it is still the same substance.
Cassini Showed Us That Saturn has Seasons
The familiar image of Saturn is a hazy yellow, but this only represents the area presently in the summer season. Cassini arrived in 2002 to see a deep blue hue to the north of the planet. This signified that the area was in a winter phase. This is when the cloud on Saturn is thinner and there is little haze. When the planet warms up through the summer, aerosols build up in the atmosphere, reflecting that familiar yellow haze. Cassini taught us that Saturn’s seasons are volatile and wild, and with clear and distinct physical indicators.
Cassini Taught Us about Saturn’s Immense Thunderstorms
Amongst the phenomena that Cassini captured, few were as important or as powerful as the detail acquired during Saturn’s many storms. Lightning and thunder were recorded, as were giant swirling masses of wind that we see on Earth. On Saturn, they have the potential to consume much of the planet when a storm breaks out. Not so on Earth due to continental boundaries and rocky topography that can take the wind out of the sail of any storm that blows up.