NASA spacecraft Cassini's 13-year mission around Saturn came to a close on Friday. Cassini far outlived its original mission and provided scientists with invaluable data. But it also provided us glimpses of a uniquely beautiful planet and its moons. Here, Enceladus, a moon that holds the possibility of life, sinks behind Saturn.

Cassini Grand Finale Enceladus

(NASA)

Mighty Titan 

Titan, Saturn's largest moon, is seen here shrouded in smog. Cassini discovered that Titan has lakes of methane, making it the only place in our solar system outside of Earth to contain liquid on its surface. One lake is prominent at the top centre of the image.

Cassini Grand Finale Saturn Titan

(NASA)

A stunning ring system

Saturn's rings are a marvellous collection of rock and ice, some as small as dust, some as large as mountains. But the age of the rings isn't known. In its final flybys, Cassini mapped the gravity fields of the rings, in essence trying to weigh them. The more massive they are, the older they would be, perhaps as old as the solar system itself, around 4.6 billion years. If lighter, they could be just hundreds of thousands of years old, which preliminary findings suggest may be the case.

Cassini Grand Finale Saturn rings

(NASA)

Making waves

The tiny moon Daphnis is seen here in the Keeler gap, making waves in the rings of Saturn. While orbiting the planet, Cassini discovered six new moons, many within the rings of Saturn itself. 

Cassini Grand Finale Daphnis rings

(NASA)

The great hexagonal north

Cassini snapped one final photo of Saturn's northern hemisphere where a powerful jet stream in the form of a hexagon swirls. The eye of the hexagon is about 50 times larger than the average eye of a hurricane on Earth.

Cassini Grand Finale Saturn northern hemisphere

(NASA)

Ring propellers

Cassini found structures scientists refer to as propellers, within the rings of Saturn. It's believed they are caused by tiny moons that disturb the ring material, which in turn reflects sunlight.

Cassini Grand Finale Saturn rings propeller

(NASA)

Final resting place

This image composite taken in infrared shows where scientists believe the spacecraft entered Saturn's atmosphere. When the photos were taken, the region was on the night side of the planet, which would have rotated into day by the time Cassini made its entry.

Cassini Grand Final impact site

(NASA)

So long, and goodnight

After 13 years, 7.9 billion kilometres travelled, 294 orbits and 453,048 images taken, Cassini bids Saturn one final goodbye. This was Cassini's final photograph, taken on Sept. 14 at 3:59 p.m. ET. The last signal was received on Earth on Sept. 15 at 7:55 a.m.

Cassini Grand Finale Saturn impact

(NASA)