Jupiter

Jupiter has a long history of surprising scientists – all the way back to 1610 when Galileo Galilei found the first moons beyond Earth. That discovery changed the way we see the universe. Jupiter is, by far, the largest planet in the solar system – more than twice as massive as all the other planets combined.

Jupiter's familiar stripes and swirls are actually cold, windy clouds of ammonia and water, floating in an atmosphere of hydrogen and helium. Jupiter’s iconic Great Red Spot is a giant storm bigger than Earth that has raged for hundreds of years.

   Jupiter Blog
Update! Pro-Am Jupiter Observing Campaign Extended
2/23/2026

The Association of Lunar and Planetary Observers invites all Jupiter observers to continue participating in an expanded international Pro-Am campaign supporting multiple professional investigations now underway. In addition to the James Webb Space Telescope (JWST) observations on February 20–21, 2026, professional teams led by Dr. Leigh Fletcher and Dr. Mike Wong report that three additional JWST programs will continue through the end of March.

Recent image of Jupiter from JWST
These observations are complemented by coordinated imaging from Juno’s Perijove 81 on February 25, creating a rare opportunity for amateurs to provide the continuous temporal coverage that spacecraft cannot. As our current announcement notes, “high-quality ground-based images provide the continuous coverage needed to track rapidly evolving atmospheric features and place spacecraft and space-telescope data in broader context.”
Professional researchers have already identified specific scientific applications for amateur data. Dr. Wong notes that Glenn Orton is measuring the time-variation of Oval BA’s color over the past decade, and that Ramana Sankar is developing machine learning tools to recognize features in ground based images - both of which benefit directly from ALPO’s long-term Jupiter archive.
We encourage observers worldwide to obtain Jupiter images through February 20–25 and throughout the continuing JWST window into March. WL, RGB, near-IR, methane-band, and long-wavelength IR images are all valuable. Please submit observations to the ALPO Jupiter Section at jupiter@alpo-astronomy.org, following the gallery guidelines. Your contributions support active professional research and help build a global, multi-wavelength record of Jupiter during this scientifically rich period.

Again, our thanks to Dr. John Rogers, Director of the BAA Jupiter Section, for alerting us to this important Pro-Am collaboration.

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   Jupiter News Headlines
Jupiter's Lightning Could Be Almost Unbelievably Powerful
3/27/2026

TBD
New data from the Juno mission reveals that Jovian lightning is far more energetic than previously estimated. Observations of a "stealth superstorm" from 2021–22 suggest individual bolts could be up to one million times more powerful than terrestrial lightning. This discovery significantly alters our understanding of the gas giant's atmospheric dynamics and the sheer scale of the electrical discharge occurring within its thick, turbulent cloud layers.

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Jupiter’s Moons May Have Formed With the Ingredients for Life
3/20/2026

TBD
Researchers from the Southwest Research Institute found that Jupiter’s icy moons, including Europa, Ganymede, and Callisto, likely inherited complex organic molecules (COMs) during their formation. By modeling the early solar system’s protoplanetary disk, the team demonstrated that these essential biological building blocks could survive transport into Jupiter’s moon-forming disk. This suggests these "ocean worlds" were born with the chemical foundations for life, providing a head start for potential prebiotic chemistry within their subsurface oceans.

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Is Jupiter on a Diet? New Measurements Say It's Smaller Than We Thought
2/8/2026

TBD
New data from NASA’s Juno spacecraft reveals that Jupiter is slightly smaller than previously believed. While earlier estimates relied on limited data from the Pioneer and Voyager missions, Juno’s 26 radio-occultation measurements have refined the planet’s dimensions, shaving approximately five miles off its equator and fifteen miles from its poles. These precise measurements are crucial for scientists to accurately model the gas giant’s internal density, temperature, and atmospheric structure.

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Apparition Highlights
   Galilean Moon Events
Moon Date (UT) Event
Io 2026-04-11 14:27 Transit-Ingress
Io 2026-04-11 15:43 Shadow-Ingress
Io 2026-04-11 16:42 Transit-Egress
Io 2026-04-11 18:00 Shadow-Egress
Callisto 2026-04-11 20:23 Occultation-Disappearance
Callisto 2026-04-12 00:27 Occultation-Reappearance
Europa 2026-04-12 06:08 Occultation-Disappearance
Callisto 2026-04-12 08:29 Eclipse-Disappearance
Europa 2026-04-12 11:40 Eclipse-Reappearance
Io 2026-04-12 11:45 Occultation-Disappearance
Callisto 2026-04-12 12:54 Eclipse-Reappearance
Io 2026-04-12 15:18 Eclipse-Reappearance
Complete Galilean Moon events can be found
in issues of Sky & Telescope
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