Uranus is a fascinating and enigmatic planet of the Solar System, with an axis of rotation tilted at 98° and an upper atmosphere whose mysterious cooling has intrigued researchers for decades. Recent studies provide a possible answer to the question “why is Uranus cooling?”, highlighting the essential role of the solar wind.
Unlike Earth and other nearby planets, where the temperature of the thermosphere is controlled by solar photons, Uranus, nearly 3 billion kilometers from the Sun, receives insufficient photons to heat its atmosphere.
New research, published in Geophysical Review Letters, shows that the solar wind, the constant stream of charged particles coming from the solar corona, has a direct effect on the temperature of the thermosphere of the planet Uranus.
Uranus is cooling
Uranus is cooling. Observations made by Voyager 2 in 1986 and continued by telescopes on Earth showed that Uranus’ temperature has dropped by 50% in recent decades.
The reduction in solar wind pressure since the 1990s has allowed the magnetosphere of the planet Uranus to expand, reducing the interaction with solar particles and decreasing atmospheric heating.
According to the team led by dr. Adam Masters. from Imperial College London (England), Uranus’ magnetosphere plays a crucial role in transferring energy from the solar wind to the atmosphere. As the pressure of the solar wind decreases, the energy transferred to the thermosphere becomes less. This change is not related to the 11-year solar cycle, but to a long-term decrease in the strength of the solar wind.
On distant planets with large magnetospheres, such as Uranus, the interaction between the solar wind and magnetic field plays a more important role than solar radiation in determining atmospheric temperature, writes Science Alert.
Implications for future missions and exoplanets
The Uranus Orbiter and Probe (UOP) mission: This mission, a priority according to the Planetary Science and Astrobiology Decadal Survey 2023-2032, could study in detail the atmosphere and magnetosphere of the planet Uranus. Understanding how solar wind energy influences the atmosphere would be a key goal.
These findings could have implications for exoplanets with strong magnetic fields and atmospheres influenced by the stellar wind, not just radiation from the host star.
The cooling of Uranus’ thermosphere is a unique example of the complex interaction between a planet and the solar wind. This phenomenon could redefine how we understand the atmospheric dynamics of distant planets and contribute to expanding knowledge about the role of the magnetosphere in protecting and shaping planetary atmospheres. In addition, these discoveries are a step forward in the search for habitable worlds outside the Solar System.
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Source: www.descopera.ro
