NASA’s Juno spacecraft recently completed its second flyby of Jupiter’s moon Io, capturing breathtaking images of the solar system’s most volcanic body. This flyby provided a unique opportunity for operators to observe Io in unprecedented detail, revealing features that haven’t been seen in over three decades.
During the flyby on February 3, Juno came within a mere 930 miles (1,500 kilometers) of Io’s surface, matching its previous flyby distance in December 2023. This close approach allowed Juno’s JunoCam instrument to capture remarkable images of the moon’s volcanic activity, including erupting plumes, lava lakes, and towering mountain peaks. One particularly stunning image captured on February 4 shows two plumes escaping from Io, providing evidence of ongoing volcanic activity.
Io, roughly the same size as Earth’s moon, stands out due to its hundreds of actively erupting volcanoes. These volcanoes have the capability to eject material dozens of miles into Io’s thin, waterless atmosphere. Scientists believe that the source of Io’s extreme volcanic activity is the gravitational influence exerted by its host planet, Jupiter, as well as the three other large Jovian moons: Europa, Ganymede, and Callisto. These moons subject Io to intense tidal forces, causing its surface to rise and fall dramatically. This tidal stress triggers the moon’s extreme volcanism.
Another captivating image captured by JunoCam on February 5 showcases Io in psychedelic colors. The image, created using data from multiple filters, reveals Io’s dark left-hand side adorned in greens and reds, while the illuminated right side takes on a fiery orange hue. Additionally, Juno captured the sub-Jovian hemisphere of Io, which faces Jupiter permanently. This is the first time this hemisphere has been observed since the Voyager 1 spacecraft flew through the Jovian system in 1979. Illuminated by light bouncing off Jupiter’s cloud tops, JunoCam detected surface changes driven by volcanic activity, including a reshaping of the compound flow field and the discovery of a new lava flow.
Juno’s extended mission, now in its third year after the primary mission concluded in July 2021, will not bring it as close to Io again. Subsequent flybys will see Juno approach the volcanic moon at increasing distances. The next close approach will be at an altitude of approximately 10,250 miles (16,500 kilometers), while the final flyby will bring the spacecraft within around 71,450 miles (115,000 kilometers) of Io. Juno’s extended mission, focused on investigating Jupiter and its moons, is scheduled to continue until September 2025 when NASA plans to intentionally crash the probe into Jupiter’s atmosphere.
The images captured by Juno during its second flyby of Io provide scientists with valuable insights into the moon’s volcanic activity and its interaction with Jupiter and its neighboring moons. These stunning images not only showcase the beauty of our solar system but also contribute to our understanding of the complex dynamics at play in this distant corner of space. As Juno continues its mission, we eagerly await further discoveries and breathtaking images that will deepen our knowledge of Jupiter and its enigmatic moon, Io.
