Shortly before 10 p.m. Monday, a NASA spacecraft in orbit around Jupiter for the past year will pass 5,600 miles above a gigantic red tempest twice the size of Earth, giving humanity our closest look at a centuries-old enigma.

Illustrations of Jupiter’s iconic “Great Red Spot” date back to the 19th century, but astronomers using the first telescopes in the 1600s described a similar blemish during their observations of the solar system’s largest planet.

“It’s lasted hundreds of years, maybe even longer,” said Scott Bolton, Juno’s principal investigator from the Southwest Research Institute. “No one knows exactly how it is made and what is keeping it alive this long.”

All eight of Juno’s scientific instruments, including its camera, will collect unprecedented data that might give insights about the source of the storm’s chaotic energy, how deep the 400 mile per hour winds extend into the planet’s atmosphere, and what causes the phenomenon’s red hue.

“It’s the first time anyone will be seeing this deep into the atmosphere,” said Glenn Orton, senior research scientist at the Jet Propulsion Laboratory. The La Cañada Flintridge facility manages the mission.

Among the oddities observed over the decades is the storm’s size. The Great Red Spot looks smaller compared to original photographs in the 1890s, Orton said. But NASA doesn’t know why the storm changed, or what that change means.

Orton recently led efforts to collect new Earth-based telescope observations of the Great Red Spot ahead of the Juno flyover. Described as a “one-two punch,” these new images from the Gemini North and Subaru telescopes on Hawaii’s Mauna Kea peak, provide context for Juno’s close-ups, he said.

Juno changed everything we know about Jupiter

If NASA has learned anything in the last year, it’s that Jupiter is not as simple as they once believed.

The basketball court-sized Juno arrived at Jupiter on July 4, 2016 after a five-year, 400-million-mile journey. Almost immediately, scientists discovered a more turbulent world than they expected.

Early scientific results suggest Jupiter has cyclones at its polar regions, a warm, ammonia-rich “tropical zone” at its equator, and a planetary core that might have partially dissolved.

NASA’s entire concept of the planet was turned on its head in just one year of research, according to Bolton, the mission’s principal investigator. The discoveries raised questions about our understanding of other gas giants in the solar system.

“We know enough to know our ideas were wrong, but we haven’t got all the truths sorted out yet,” he said. “In the first year, we’ve been able to confirm not only is Jupiter incredibly interesting and puzzling, but that we have the right tools. The science instruments are the right ones for us to really resolve these questions and better understand the planet.”

Stunning new images of the Great Red Spot

Monday is only Juno’s sixth flyby — the spacecraft’s orbit takes 53 days. The team will begin getting data within hours and expects to collect everything within three days.

Images of the Great Red Spot will become available to the public through the JunoCam website almost immediately. The spacecraft’s camera is primarily a public outreach tool that lets amateur and professional astronomers view and process raw images as the files are beamed back.

Bolton said the community has created both artistic and scientifically accurate depictions of Jupiter, many of which have been stunning, including a video constructed from Juno’s snapshots.

“The whole world is waiting to see what the Great Red Spot looks like up close,” he said. “The first person that is going to see what that looks like isn’t going to be some NASA scientist, it’s going to be whoever goes on the website first.”