July 28, 2016

Jupiter’s Spot Gives It A Hot Flush


It is the biggest storm in the solar system. Now scientists have found it acts as an underfoot heater for a mysterious hotspot high above our sun’s biggest planet.
US astronomers have discovered that Jupiter’s “great red spot”, a swirling morass of shifting colours up to three times as wide as Earth, is teleporting heat to the sparse air 800km above it.

The discovery, reported this morning in the journal Nature, explains why Jupiter’s upper atmosphere is ferociously hot despite being so far from the sun. The findings suggest a previously unknown form of energy transmission may be lighting up some of the coldest places in the cosmos.

Scientists have long wondered why the upper atmospheres of the gas giants — Jupiter, Saturn, Uranus and Neptune — are hundreds of degrees hotter than models say they should be. Lead author James O’Donoghue, of Boston University, told The Australian that temperatures above Jupiter exceeded 600C — roughly on par with Earth’s outer atmosphere, even though Jupiter is about five times as far from the sun and receives only 3 per cent as much sunlight.

The mystery, which astronomers have termed the “energy crisis”, has baffled them for more than 40 years. The Boston team tackled it by sampling temperatures in different zones of Jupiter’s upper atmosphere, compiling nine hours of infra-red readings from a telescope on a Hawaiian mountain.

“We could see almost immediately that our maximum temperatures at high altitudes were above the great red spot,” Dr O’Donoghue said.

Discovered in the 17th century, the spot is a massive hurricane thought to have been raging for more than 300 years. It spins at up to 360kmh, with no land to stop it, although its size and colour have varied over the centuries.

The team believes sound waves above the giant storm are radiating upwards and heating the atmosphere far above. A similar phenomenon has been observed above thunderstorms in the Andes Mountains, it says.

Dr O’Donoghue said the acoustic waves appeared to be teaming up with “gravity waves” in a combination never previously observed.

 Gravity waves, which are distinct from Einstein’s gravitational waves, are oscillations caused by gravity’s effects in atmospheres and oceans.
He said the densities of the upper atmospheres of any planet were incredibly low, making very high temperatures “easily achievable”. “You wouldn’t burn your hand in these atmospheres because not enough gas would be in contact with you,” he noted.

By John Ross
With many thanks to The Australian