Jupiter's energetic crisis' is caused by auroras.

The mysterious "energy crisis" of Jupiter, which has intrigued astronomers for 50 years, could be at the origin of aurorae, suggest new observations.

The largest planet in our solar system has long been known to be remarkably hot, despite being far from the sun. Jupiter is located at more than 5 astronomical units, or distances sun-Earth (1 AU is one million miles (150 million kilometers)).

There's so little sunlight that far from the sun than Jupiter's upper atmosphere should be frigid, scientists estimate it should be about -100 degrees Fahrenheit (-73 degrees Celsius), according to a NASA statement. However, the mean temperature in Jupiter's upper atmosphere is 800 degrees Fahrenheit (426 degrees Celsius), nearly as high as the surface of the infernal planet Venus.

Astronomers have been discussing the causes of the 'energy crisis' on Jupiter for decades, as they call it. A new study has shown that the planet's intense auroras, fed by the planet's strong magnetic field, are what makes temperatures rise.

Auroras are common phenomena in our solar system, which occur on planets that have important magnetic fields like Earth and Jupiter. (Mars and Venus have their own flavors of aurora, but these lights work differently on these planets due to the patchy magnetic environment in these areas.

In worlds where magnetic fields are strong such as Earth and Jupiter, auroras occur when electrically charged particles are trapped in the magnetic field and spiral to the poles. Along the path of the poles, particles strike atoms and molecules into the atmosphere, producing light.

The auroral heating conclusion at Jupiter comes, in part, from new observations by NASA's Juno spacecraft, which is dipping in and out of the intense radiation field to study the planet up close. Juno's close-up perspective enables scientists to follow global warming with unprecedented detail.

"Imagine that as a beach: if the warm atmosphere is water, the magnetic field mapped by Juno is the shoreline, and the aurora is the ocean. We found that water left the ocean and flooded the land, and Juno revealed where that shoreline was helping us understand the degree of flooding," James O'Donoghue, lead author of the research, said in a statement from the Keck Observatory.

The team used observations by Juno and the Japan Aerospace Exploration Agency (JAXA) Hisaki satellite, both of which followed the planet's magnetic field. They also used data from the Keck II telescope to provide high-resolution temperature maps. Together, these observations allowed scientists to observe an aurora emitting a heat pulse towards Jupiter's equator. Long-term Hisaki observations since 2013 also showed the importance of the solar wind — the constant stream of particles from the sun — which brings its own magnetic field to Jupiter and likely enhanced the observed auroras.

"We were fortunate to capture this potential heat dissipation event," said Dr. O'Donoghue, a global space scientist at JAXA's Institute of Space and Astronautics. "Had we seen Jupiter on a different night, when the pressure of the solar wind had not been high recently, we would have missed it?"

Using a near-infrared spectrograph, Keck traced the planet's heat in two observing sessions — in April 2016 and January 2017 — from electrically charged hydrogen molecules as they moved from the poles of the planet to the equator. Keck II also was configured to improve the resolution of its imagery by taking more temperature measurements and only including those with a high degree of certainty addressed to the value. This work took years, but the result was new temperature maps with over 10,000 individual data points, significantly improving the efforts spent on resolving.

However, the high-definition view also showed a further heating mystery that has not yet been solved.

"We also revealed a strange, localized region of heating well away from the aurora — a long bar of heating unlike anything we've seen before," Tom Stallard, a co-author of the paper at the University of Leicester, said in the Keck statement. "Although we are not sure of the nature of this characteristic, I am convinced that it is a heatwave circulating towards the equator from the dawn."

The magnetic field of Jupiter is stronger than that of Earth. A nearby Jovian volcanic moon — Io — discharges a lot of matter into the region through eruptions, providing a lot of particles that enter Jupiter's atmosphere. The size of Jupiter and the strong winds also play a role in how the available auroral heat circulates on the planet.

Although auroral heating is not a new idea, scientists have been unable to confirm this hypothesis thus far.

Previously, models examining the planet's upper atmosphere suggested that the auroral winds would not make it to the equator. On the contrary, the theory suggests that the winds would be driven west due to the rapid rotation of Jupiter, which is nearly 10 hours long and varies slightly by latitude because the planet is gaseous. The new observations refute this old thought and also suggest that the westerly winds may be lower than the equatorial winds pulling away from the auroral heat.