NASA’s 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.

“It started to tantalizingly teach us about the universe itself,” Hadfield told CTV News Channel Friday.

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

1. Geysers on Enceladus

Delaney hailed the probe for revealing the true nature of Saturn’s 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.

“We know there’s 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,” said Hadfield.

2. Titan

Delaney told CTV News Channel Thursday Cassini has helped fill in a lot of the gaps in what scientists know about Titan, Saturn’s largest moon. He said the probe essentially defined Titan as a “real body in the solar system,” 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’s atmosphere – 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’s 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.

“If you glance at it, it could be somewhere on Earth,” said Hadfield. “To think that that exists out there just opens our minds to the possibilities of environments around the solar system and the universe.”

4. Saturn’s polar hexagon

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

5. Saturn’s rings

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

“Its ring structure is far more complex than we had anticipated,” Delaney said. “It’s just a wonderful choreography of interactions for all of the Saturnian system components.”

“Now we understand [the rings] are primarily ice, and water ice, and it’s a temporary thing,” added Hadfield.