This is Juno’s second brush with Jupiter. Scientists are expecting to uncover the mystery behind its formation, and truth about the Great Red Spot.
NASA Jupiter probe has sent images showing gigantic storms on the solar system’s largest planet, Jupiter.
Launched on August 5, 2011, Juno entered Jupiter’s orbit on July 4, 2016. The spacecraft has been orbiting Jupiter for nearly a year now. Its first reports are revealing the gas giant to be more complex and surprising than ever thought.
Juno’s equipment is sending information about the massive cyclones dominating the planet’s poles, while a deep tropical band of ammonia circling its equator. Meanwhile, the planet’s magnetic field is turning out to be much stronger than expected. Jupiter’s gravity field is indicating that its interior core may not be super dense. All these findings, published in two new studies, on Thursday – Science and Geophysical Research Letters — will eventually help planetary scientists piece together the structure of Jupiter. This would decode the mysteries to Jupiter’s formation, which is estimated to be billions of years old.
These new tantalizing clues about Jupiter were gathered by Juno during its first couple of passes by the planet. Right now, Juno is in an extremely elliptical orbit, which brings the probe screeching by Jupiter’s surface for a few hours at a time during each trip around the planet. These passes, known as Perijove passes, bring Juno over the planet’s poles — closer than any previous vehicle has gone before. And it’s during these swings by Jupiter that Juno gathers the bulk of its data. Currently Juno does one Perijove pass every 53 days.
Juno’s camera spotted the chaotic weather at the top and bottom of Jupiter once it began skimming the cloud tops last year. Jupiter’s poles are covered in Earth-sized swirling storms that are densely clustered and rubbing together, neither pole having the same number of storms or configurations. Moreover, they look very different from the poles of Saturn, making these cyclones of Jupiter’s poles unique.
“We’re puzzled as to how they could be formed, how stable the configuration is, and why Jupiter’s North Pole doesn’t look like the South Pole,” Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio said in an official statement.
The spacecraft captured one giant storm right over the terminator — the moving line that separates day from night on a planet. It created shadows that allowed the mission team to calculate exactly where the storm sat, finding that it was actually sticking up out of the atmosphere. And this storm was huge, reaching 30 to 60 miles high with a diameter of about 1,700 miles (2,800 kilometers) which is about half the width of Earth.
Scientists are eager to see, over time, whether these super cyclones are stable or dynamic. “Are they going to stay the same way for years and years like the Great Red Spot … Of course, only time will tell,” Bolton said.
Jupiter’s poles appear dramatically different from neighboring Saturn’s, according to the scientists, with nothing like the hexagon-shaped cloud system over Saturn’s North Pole. At the same time, the two poles don’t really resemble each other, which is puzzling, according to Bolton.
“When you get over the poles, it’s a very different looking planet,” Bolton said. “I’m not sure you’d even recognize it as Jupiter if you didn’t know.”
Juno is specifically equipped with instruments that — for the first time — can peak underneath Jupiter’s cloud tops, to figure out the composition of the planet below.
Measurements have revealed a super-deep band of ammonia around the planet’s equator — and it goes as deep into the planet as the spacecraft can see.
Bolton compares the ammonia band to the tropical band around Earth — the region around the equator that has its own distinct climate. “Earth’s band is driven by the fact that there’s a surface and ocean underneath, but Jupiter is all gas and yet we see the same kind of feature,” he said. And the ammonia isn’t just found at the equator either. Bolton says the concentration of ammonia is highly variable throughout Jupiter, making the planet’s composition incredibly diverse.
“The naive simple view of giant planets is that as soon as you scratched beneath the surface where the sunlight was no longer getting to, then everything would just be this boring well-mixed sphere of gas that all looked the same,” said Bolton. “And Jupiter is anything but that; it’s very complicated.”
One thing that Juno has marked is that the closer it gets to Jupiter, the more variation it finds in the strength of the magnetic field. “When we get really close to the planet, we’re getting much higher highs and much lower lows than we would have anticipated based on our current knowledge,” NASA quotes Jack Connerney, an astrophysicist at NASA’s Goddard Space Flight Center and lead author on one of the Science papers. And that provides some clues as to where inside the planet the magnetic field is being generated. Surprisingly strong magnetic field in places – roughly 10 times greater than Earth’s is recorded. It’s also led scientists to believe Jupiter may have a “fuzzy” core – as Bolton puts it – big but partially dissolved.
Juno also is designed to study the polar magnetosphere and the origin of Jupiter’s powerful auroras — its northern and southern lights. These auroral emissions are caused by particles that pick up energy, slamming into atmospheric molecules. Juno’s initial observations indicate that the process seems to work differently in Jupiter than in Earth.
Launched on last summer, Juno is providing the best close-up views ever of our solar system’s largest planet, peering beneath the clouds for a true portrait.
“Juno is a mapping mission; we’re going to go over the planet 32 different times and each time at different longitudes,” Bolton said, “So we don’t want to make too many assumptions just yet. We need to finish that map.” However, Bolton is confident that the NASA spacecraft will be able to deliver some solid answers about Jupiter after a while. “Juno is the right tool to sort this out,” he said.
It’s made five close passes over Jupiter so far for science collection, the most recent last week. These passes occur about every two months given Juno’s extremely oblong orbit. The next one will be in July, with investigators targeting the Great Red Spot.
Juno is moving so fast during these chummy encounters that it takes only two hours to get from the north pole to the south.
“We are excited to share these early discoveries, which help us better understand what makes Jupiter so fascinating,” Diane Brown, Juno programme executive at NASA Headquarters in Washington said in a statement published on NASA’s official websit.