A selection of photographs taken by Cassini. Photos: NASA/JPL-Caltech/Space Science Institute

The Cassini spacecraft has been in orbit around Saturn for 13 years, beaming data and photographs back to Earth. When it deliberately dove into Saturn's atmosphere today, it marked the end of one of our most in-depth looks at an alien planet to date and our only link to the Saturnian system. There are no plans to return.

The mission might be over, but there are discoveries yet to come as scientists sift through over 635 gigabytes of data sent back to Earth. Although we're certainly leaving out some (shoutout to Pan, the ravioli-shaped moon that took the internet by storm), here are three top findings so far.

1. Moons that could harbor life

Enceladus, the icy ocean moon. Cassini revealed that under Enceladus' icy surface there is a vast salty ocean, and plumes of it erupt from the South Pole like geysers. This discovery "changed almost the entire focus of the mission," writes JoAnna Wendel for Eos, because liquid water could mean life.

Titan, the gassy moon. A previous flyby from the Voyager spacecraft had shown that Titan had an atmosphere, so European Space Agency scientists created Huygens, a probe delivered by Cassini and dropped on Titan to sample the surroundings. It found vinyl cyanide, a complex molecule that some think could be a building block for alien life, as well as methane clouds, lakes and rivers: something akin to the water cycle on earth, but with methane instead of water.

And possibly more. Not all of Cassini's data has been analyzed, but there's some evidence that the tiny moon Dione has an internal ocean.

Why it matters: Along with Jupiter's Europa, Titan and Enceladus have redefined where we might find life beyond Earth.

2. Details about Saturn's rings

Once thought to be flat, Cassini's pictures revealed the dynamic landscape of Saturn's rings. There are dramatic spikes a mile and a half tall. Density waves form ripples in the rings, which come from the same processes that make the spirals in our own galaxy. And there's an empty gap between the rings and Saturn that Cassini dove through to record what it sounds like.

Why it matters: Tiny, propeller-like moons-to-be are scattered throughout these structures. They provide a glimpse into the early days of our solar system, when planets may have been propellers in a dustcloud around our Sun.

3. Some mind-blowing pictures

What's next: As Cassini falls towards Saturn, it'll sample the planet's atmosphere and take a few key readings. So far, scientists have struggled to get the magnetic measurements necessary to determine the length of a Saturnian day — but Cassini's last transmissions might contain that key data.

Go deeper:

  • Shannon Stirone explains what it takes to kill a spacecraft for The Atlantic. "Thousands will gather at JPL and wait until the early morning hours for Cassini's final orbit to begin. They'll share stories of a lifetime of work, as that effort culminates in fireworks 800 million miles away."
  • At the LA Times, Linda Netburn writes about how Cassini came to be. "This is the story of how it got off the ground, told by the people who were there."
  • Science News' Lisa Grossman highlights some of the best 'postcards' Cassini sent back to Earth: "After all this time, we've witnessed only the transitions to Saturnian spring and summer, the equivalent of January to June on Earth. And yet we've seen so much."

Go deeper

Updated 33 mins ago - Politics & Policy

Primary races to watch in Arizona, Kansas, Michigan, Missouri, Washington

Photo: Michael B. Thomas/Getty Images

Primary elections on Tuesday in fives states see crowded fields of both Republicans and Democrats hoping to make the ballot in 2020.

What to watch: Rep. Rashida Tlaib (D-Mich.) is "fighting for her political life" in a tight primary race against Detroit City Council President Brenda Jones, who Tlaib beat by 900 votes in 2018, The New York Times writes. Senate Republicans are also watching the primary race in Kansas to see who could replace retiring Republican Sen. Pat Roberts.

Updated 1 hour ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 8:30 p.m. ET: 18,448,084 — Total deaths: 698,023 — Total recoveries — 11,048,174Map.
  2. U.S.: Total confirmed cases as of 8:30 p.m. ET: 4,765,170 — Total deaths: 156,668 — Total recoveries: 1,528,979 — Total tests: 57,543,852Map.
  3. States: New York City health commissioner resigns in protest of De Blasio's coronavirus response — Local governments go to war over schools.
  4. Public health: 59% of Americans support nationwide 2-week stay-at-home order in NPR poll.
  5. Politics: Trump's national security adviser returns to work after coronavirus recovery Republicans push to expand small business loan program.
  6. Sports: Indy 500 to be held without fansRafael Nadal opts out of U.S. Open.
Updated 4 hours ago - World

At least 50 killed, 3,000 injured after massive explosion rocks Beirut

Photo: Anwar Amro/AFP via Getty Images

A major explosion has slammed central Beirut, Lebanon, damaging buildings as far as several miles away and injuring scores of people.

Driving the news: Lebanon's health minister said in televised remarks that more than 50 people have been killed and over 3,000 injured. Prime Minister Hassan Diab said the explosions occurred at a warehouse that had been storing 2,750 tons of ammonium nitrate for the past six years, per NBC.