Affectionately called the gas giant, Jupiter is made up of 99 % hydrogen and helium. It’s 11 times wider than Earth and 300 times more massive. Doesn’t paint a clear enough picture of the planetary goliath for you? Consider this: it’s big enough that 1 300 Earths could fit inside it!
NASA spacecraft Juno has been orbiting Jupiter since 2016. The mission is to learn more about the planet’s origins and hidden properties, such as its gravitational field, the depth of its atmospheric jets and its composition beneath the clouds. Juno’s new data is in, and oh, what tales its observations can tell!
Probing Jupiter’s depths
Jupiter’s surface with its bands of gas and winds has been studied extensively, but little is known about what lies below its visible clouds and the dynamics at play. Thanks to Juno’s gravity measurements, this outer layer extends to a depth of 3 000 km. This and other key mission findings were published in a series of four articles in the British journal ‘Nature’
According to Juno scientist and lead author Tristan Guillot, the long-time mystery is now solved. He told the ‘BBC’
: “For over 40 years we didn’t know whether the bands would go all the way to the centre, or whether they were just skin deep. Three thousand kilometres is actually quite deep. It’s 1 % of the mass of the planet. Jupiter’s very big so it’s about three Earth masses that are involved in this motion.”
Guillot said that “this is all really important for understanding atmospheric dynamics, not just on Jupiter but on other gaseous planets like Saturn, Uranus and Neptune and also the exoplanets we’re now discovering.”
Quoted by the ‘Associated Press’
, Yohai Kaspi, Juno co-investigator and another one of the lead authors, added: “The result is a surprise because this indicates that the atmosphere of Jupiter is massive and extends much deeper than we previously expected.”
Jupiter inside out
Another significant discovery was that massive cyclones spin above Jupiter’s north and south poles. These bizarre weather patterns are a first in our solar system. In all, nine cyclones were spotted over the north and six over the south. With wind speeds up to about 350 km/h in places, they top Category 5 hurricane strength.
In addition to the cyclones, Jupiter’s powerful jet streams actually penetrate thousands of kilometres beneath the clouds. This shows that its atmosphere is massive and ranges far deeper than scientists previously thought.
The mission also found that below the 3 000 km depth, Jupiter’s interior rotates almost as a solid body. This is in spite of its fluid nature.
Whether Jupiter has a rocky core or not remains a mystery. Juno hasn’t solved this puzzle yet. The problem is, Juno’s joy ride is ending in the summer. NASA is looking to keep the spacecraft out there for a while longer.
The recent discoveries may very well have knock-on effects for other worlds in our solar system and the galaxy. Time will tell if this newfound enthusiasm for space exploration could lead to more missions to other large planets.