Jupiter’s hot spot creates puzzle
Scientists scanning Jupiter’s atmosphere have found a mysterious spike in temperature high above the Great Red Spot – the massive, swirling storm that has graced the planet’s face for centuries.
The discovery, described in the journal Nature, may hint at a deeper connection between the dynamics of the gas giant’s upper and lower atmosphere, and could shed light on the basic physics of such planets in our solar system and beyond.
For more than four decades, scientists have struggled to explain why the temperatures in parts of the giant planets’ upper atmospheres can be hundreds of degrees warmer than expected — too warm to be explained by heating from the Sun.
‘‘Jupiter, Saturn, Uranus and Neptune are all far too hot in their upper atmospheres compared to the amount of sunlight they receive,’’ said lead author James O’Donoghue, a planetary scientist at Boston University.
‘‘For example, Jupiter should be about 200 degrees Kelvin (-73C), whereas we consistently measure it to be over 1000 (726C). So it’s a massive discrepancy.’’
To find out where this heat was coming from, a team of scientists from Boston University and the University of Leicester used a spectrometer at the Nasa Infrared Telescope Facility to create a map of the temperature distribution across the striped gas giant. To do so, they tracked emission lines from a triple-hydrogen ion found in Jupiter’s atmosphere.
The scientists were expecting to see the polar atmosphere show up brightly, given that those regions have massive auroras energised by the planet’s powerful magnetic field. But they were not expecting the Great Red Spot to pop out of the haze near the equator as well.
The Great Red Spot sits about 50 kilometres above the so-called surface, the depth at which the planet reaches Earth’s sea-level pressure. But the overheated layers in the upper atmosphere sit much higher, around 600-1000km above the surface.
There, the temperature above the storm came out to a whopping 1600 degrees Kelvin (1327C). That means that whatever was happening in the Great Red Spot was having a significant effect far above it.
What the exact dynamics are, however, remains unclear.
‘‘The lack of a solution points to a huge misunderstanding in our fundamental knowledge of how an atmosphere works,’’ O’Donoghue said.
The scientists want to see if they can find similar hot spots hovering over smaller storms on the gas giant.