Juno
Watch Live: Juno's Io Encounter
On Saturday, Feb. 3, NASA's Juno spacecraft will buzz Jupiter's volcanic moon, Io – passing less than 1,000 miles above its turbulent surface.
About 12:48 p.m. EST (9:48 a.m. PST), Juno will reach its closest point above Io – roughly 935 miles from its unstable surface, or the distance from New York City to Orlando, Florida. It's the spacecraft's second such encounter in five weeks, and mission scientists hope the visits will expose the source of Io’s massive volcanic activity, whether a magma ocean exists underneath its crust, and the effects of tidal forces from behemoth Jupiter pushing and pulling this moon, only a bit larger than Earth's moon. Meanwhile, the gravitational pull of Io on Juno during the Feb. 3 flyby is expected to reduce the spacecraft’s orbit around Jupiter to 33 days. It originally had been circling Jupiter and its environs in 53-day orbits, after it arrived at the giant planet on July 4, 2016.
Follow Along with NASA's 3D Interactive, Eyes on the Solar SystemIo, Ready for Its Close-Up
On Saturday, Feb. 3, the Juno spacecraft will sail past Jupiter's "tortured moon," following up a close flyby on Dec. 30, when it captured unprecedented images and data.
Juno's encounter with Io was the closest since a visit by the Galileo spacecraft in October 2001. And Juno is scheduled to make another pass Feb. 3, studying the most volcanically active world in the solar system, only a bit larger than Earth's Moon. Io is caught in a tug-of-war between Jupiter's powerful gravity and the smaller pull from two neighboring moons, churning its insides and creating eruptions and lakes of lava that cover its surface. See where Juno is now, or sail along with the spacecraft during its Feb. 3 flyby, using NASA's 3D interactive, Eyes on the Solar System.
Relive the Dec. 30 Flyby on NASA's EyesJuno makes closest visit to volcanic moon since 2001
The Dec. 30 flyby of Jupiter's moon Io – the most volcanic world in our solar system – offers the nearest view since the Galileo orbiter visited two decades ago.
Juno has monitored Io from afar since the spacecraft arrived at Jupiter in 2016. Then, as part of its 57th orbit around Jupiter, Juno came within roughly 930 miles (1,500 kilometers) of Io's surface – less than the distance between Los Angeles and Seattle. It will make another close pass Feb. 3, enabling scientists to compare data and images from these visits with previous observations that Juno and other craft made of this volatile world, slightly larger than Earth's Moon.
Read More About the FlybyJupiter's Volatile Moon, Io
The turbulent world is dotted with hundreds of volcanoes, some erupting so powerfully they're visible with large telescopes on Earth
The moon – one of four that astronomer Galileo Galilei discovered to be orbiting Jupiter in 1610 – is caught in a gravitational tug-of-war between its sibling moons, Europa and Ganymede, and the massive Jupiter. This creates tremendous tidal forces, like ocean tides on Earth, but which cause Io's solid surface to bulge up and down (or in and out) by as much as 330 feet (100 meters).
Read More About IoImage processing by Alain Mirón Velázquez © CC BY
juno firsts
After enduring a five-year, 1.7 billion-mile journey from Earth, and navigating the dangerous radiation in Jupiter's extensive magnetic field, Juno has provided breathtaking images and breakthrough discoveries from Jupiter and its moons. And in their quest to engage and inspire the public, the Juno mission team shares the data and pictures with the world, fueling citizen science and creative artistry.
Embarking on 53-day orbits reaching from Jupiter’s cloud tops to the frontiers of its magnetic field, Juno has upended our views of the gas giant and its surroundings. The spacecraft recently found evidence of organic compounds and salts on the large moon Ganymede – remnants of a deep underground ocean that once reached its surface – and answered a decades-old question about winds on Jupiter extending hundreds of miles toward the planet’s interior. Juno is scheduled to continue investigating the solar system’s largest planet, its moons, faint rings, and surrounding environment through September 2025.