What NASA Found on Io | Jupiter's Most Violent Moon

Added: 2026-05-18

[00:00:00]March 5th, 1979.

[00:00:04]The Voyager 1 spacecraft flies past Jupiter [music] at 60,000 km/h.

[00:00:10]Scientists are thrilled.

[00:00:12]>> [music] >> They expect to see a dead, cratered moon similar to our own.

[00:00:17]What they got instead was something that made jaws drop across NASA.

[00:00:23]Navigation engineer Linda Morabito was the first to see it.

[00:00:28]While analyzing an image of Io to check the spacecraft's position, she noticed something strange rising above the moon's limb.

[00:00:36]A giant, umbrella-shaped [music] plume.

[00:00:40]At first, she thought it was another moon behind Io.

[00:00:43]It was not.

[00:00:45]It was a volcanic eruption.

[00:00:47]The first active volcano ever discovered on another world. And it was not alone.

[00:00:54]By the time the Voyager team finished reviewing the images, they had found eight active volcanoes erupting [music] simultaneously.

[00:01:03]Eight. On a single moon.

[00:01:05]The plumes reached heights of up to 500 km.

[00:01:10]More than 40 times taller than Mount Everest.

[00:01:14]And the material being ejected was not just rock.

[00:01:17]It was sulfur dioxide, a gas that freezes immediately in space [music] and falls back to the surface as a fine, yellow-orange frost.

[00:01:27]This is why Io looks the way it does.

[00:01:30]That distinctive yellow color? That is sulfur. The red and brown patches?

[00:01:35]>> [music] >> Different forms of sulfur at different temperatures.