NASA鈥檚 Cassini spacecraft met a fiery end in the atmosphere over Saturn Friday. York University astronomy professor Paul Delaney and former Canadian astronaut Chris Hadfield highlighted the probe's five greatest discoveries from its 13 years orbiting the planet.

鈥淚t started to tantalizingly teach us about the universe itself,鈥� Hadfield told 麻豆影视 Channel Friday.

Here are Delaney鈥檚 and Hadfield鈥檚 top picks from what we learned about Earth鈥檚 distant solar neighbour.

1. Geysers on Enceladus

Delaney hailed the probe for revealing the true nature of Saturn鈥檚 tiny moon, Enceladus. Little was known about Enceladus until Cassini revealed a global ocean of liquid salt water under its crust, as well as chemical-spewing geysers that hint at the possibility Enceladus might be capable of supporting life.

鈥淲e know there鈥檚 a place, even way out there in the solar system, that has liquid water and a hot central core, [which are] the kind of conditions that life developed on Earth 4 billion years ago,鈥� said Hadfield.

2. Titan

Delaney told 麻豆影视 Channel Thursday Cassini has helped fill in a lot of the gaps in what scientists know about Titan, Saturn鈥檚 largest moon. He said the probe essentially defined Titan as a 鈥渞eal body in the solar system,鈥� and revealed a vast amount of information about its atmosphere. Among those discoveries was the fact that the atmosphere is over 95 per cent nitrogen, making it very similar to Earth鈥檚 atmosphere 鈥� although still lacking in oxygen.

3. Lakes of methane

Delaney said one of the biggest surprises of the trip was that the lakes dotting Titan鈥檚 surface appear to be rich in methane. The discovery showed that rain falls on Titan, and provided evidence of an underground ocean that might hold water and ammonia.

鈥淚f you glance at it, it could be somewhere on Earth,鈥� said Hadfield. 鈥淭o think that that exists out there just opens our minds to the possibilities of environments around the solar system and the universe.鈥�

4. Saturn鈥檚 polar hexagon

Cassini offered astronomers their closest look yet at a bizarre hexagonal shape at one of Saturn鈥檚 poles, which many are still trying to explain.

5. Saturn鈥檚 rings

Delaney and Hadfield both said the single greatest discovery of the mission has been new insights into the intricate nature of Saturn鈥檚 rings.

鈥淚ts ring structure is far more complex than we had anticipated,鈥� Delaney said. 鈥淚t鈥檚 just a wonderful choreography of interactions for all of the Saturnian system components.鈥�

鈥淣ow we understand [the rings] are primarily ice, and water ice, and it鈥檚 a temporary thing,鈥� added Hadfield.