Discovery Regarding Uranus and Neptune's Winds Unveils New Insight into the Formation of Planets
Uranus and Neptune are both home to extreme winds blowing at speeds of hundreds of miles per hour – or, as in the case of Neptune, up to 1,500 miles per hour - and hurricane-like storms as large around as Earth.
However, since the discovery of these strong atmospheric winds in the 1980s, just how deep their reach is has remained a mystery.
That is, until now.
A team led by Yohai Kaspi of the Weizmann Institute’s Environemntal Sciences and Energy Research Department realized they had a way to determine the upper limit for the thickness of the atmospheric layer based on a method used for analyzing the gravitational field of the planets.
Because irregularities in the distribution of mass cause fluctuations in the gravitational field (for example, an airplane flying near a large mountain will experience a slight pull from it), and because of the planets' rapid rotations, the researchers were able to deduce the relations between the distribution of pressure and density as well as the planets’ wind field.
Once they did this, Kaspi and his co-authors were able to calculate the gravity signature of the wind patterns and create a wind-induced gravity map of both Neptune and Uranus.
The researchers then computed the gravitational fields of a large range of planet models with no wind and compared them to the observed gravitational fields, ultimately obtaining the upper limits to the meteorological contribution to the gravitational field.
The result, based on this information, was a confinement of the streams of gas observed in the atmosphere to a “weather-layer” of no more than 620 miles in depth – an amount that only accounts for a fraction of a percent of the mass of either planet.
Knowing this can only help scientists in the quest of discovering the winds' origins, say the researchers and, according to Kaspi, how planets everywhere form.
“When it comes to thinking about the effects of dynamics on planetary formation, we’re saying the bottom 90 percent of giant planets is static,” Kaspi told Space.com.