Jupiter’s mysteries: First results from the Juno mission

This image shows Jupiter's south pole, as seen by NASA's Juno spacecraft from an altitude of 32,000 miles (52,000 kilometers). The oval features are cyclones, up to 600 miles (1,000 kilometers) in diameter.

Beneath its heavy cloud cover, Jupiter has been able to keep its secrets from astronomers. Now, first results from NASA’s Juno mission are challenging researchers’ beliefs about the gas giant.

The results were revealed during a media teleconference Thursday with NASA researchers and published in corresponding studies through the journal Science and Geophysical Research Letters.

Juno launched in August 2011 but didn’t arrive at Jupiter until July. The craft has been orbiting the planet and performing calculated flybys over the clouds.

During those flybys, observations and data showed Jupiter’s previously unseen poles. Bright ovals at the poles were revealed to be gigantic cyclones spanning 870 miles. Juno was also able to probe the cloud cover and discover wells of ammonia that form giant and violent weather systems in the deep atmosphere.

Juno revealed that Jupiter’s magnetic field is 10 times that of Earth’s and and twice as strong as anticipated, exceeding researchers’ expectations. The mission had an encounter with the planet’s “bow shock,” akin to a type of stationary shockwave, when exploring Jupiter’s magnetosphere.

The researchers compared this bow shock to a Hadley cell on Earth, without the rain. A Hadley cell is the atmospheric circulation of air rising near the equator that creates hurricanes, jet streams, trade winds and rain belts.

Juno also encountered Jupiter’s huge auroras, captured in ultraviolet and infrared images, and the electron beam pushing energy into the planet’s upper atmosphere, which could be creating the auroras.

And Juno was able to measure Jupiter’s gravitational field. That data, combined with information to be gathered as Juno’s mission continues, can help researchers determine the structure of Jupiter’s atmosphere and answer the big question: Does the planet have a solid core?

Previous models have suggested this, but Juno’s unique data could provide actual insight. If the planet has a solid core, it could change the belief that the gas giant is largely composed of hydrogen and helium.

Luckily, Juno is just getting started.

Even though Jupiter is the largest planet in our solar system, astronomers don’t know much about its origin. The Juno mission was designed to collect data and observations that will reveal the origin and evolution of the gas giant. Its other objectives include mapping Jupiter’s gravitational and magnetic fields, observing auroras, measuring the amount of water and ammonia in its atmosphere and finding evidence of a solid core.

The planet’s cloudy atmosphere has contributed greatly to obscuring general knowledge. Juno was designed to dip below those clouds to look at the planet underneath. This will also help astronomers determine finer points about Jupiter’s composition and how much of it is water.

Jupiter was most likely the first planet to form in the solar system and contains some of the same ingredients of the collapsing nebula that formed the system. Knowing more about Jupiter can provide greater insight about its beginnings.

Given the fact that gas giants are common around other stars, this could inform future observations of exoplanets and other planetary systems.