An international astronomical research team has been monitoring temperature changes in Neptune’s atmosphere for 17 years using ground-based and space-based telescopes, including the European Southern Observatory’s Very Large Telescope (ESO VLT). For the first time during the observation period, a surprisingly strong decrease in the temperature of the entire planet was recorded, followed by a sharp rise in temperatures around the south pole of the orb.
These were unexpected events.” Michael Roman will be a postdoctoral researcher at the University of Leicester in the UK, and author of a scientific paper in The Planetary Science Journal. – As we experienced early summer in the southern hemisphere of Neptune, we expected the atmosphere to slowly warm rather than cool.”
Like Earth, Neptune changes the seasons as the planet revolves around the sun.
But in this distant celestial body, each season is about 40 years long, because one year of Neptune corresponds to 165 years on Earth.
It’s been summer in the southern hemisphere since 2005. Astronomers wanted to know how the temperature would change after the summer solstice in the planet’s southern hemisphere.
Over the course of 17 years, researchers have recorded nearly 100 images of the planet in the infrared range to determine trends in atmospheric temperature change in more detail than ever before.
The data showed that a large part of the planet has gotten colder over the past two decades, despite the arrival of the southern summer. The average temperature of Neptune’s atmosphere decreased by 8 degrees Celsius between 2003 and 2018.
The astronomers were also surprised to discover that the region around Antarctica had suddenly warmed dramatically over the past two years. Between 2018 and 2020, the average temperature here showed an increase of 11°C.
Although researchers have known about Neptune’s warm polar vortex for years, such rapid warming had not previously been observed in the Arctic.
“Our data covers less than half of the entire season, and no one expected such strong and rapid changes during that time,” said Glenn Orton, co-author of the study at the University of California, California’s Jet Propulsion Laboratory (JPL). / California Institute of Technology).
Astronomers have measured the temperature of Neptune using thermal imaging devices. These instruments detect thermal radiation emitted by a celestial body in the infrared wavelength range. As part of the program, researchers collected all recorded Earth observations about Neptune over the past two decades. The study looked at infrared light emitted by Neptune’s upper atmosphere, the stratosphere. In this way, astronomers were able to reconstruct Neptune’s atmosphere temperature and its changes during part of the southern summer.
Since Neptune is located about 4.5 billion kilometers away and is very cold, its average temperature does not exceed -220 ° C, so it is not easy to measure the temperature of the planet’s atmosphere. “This type of study is only possible with sensitive infrared images, with giant telescopes like the VLT that can clearly detect Neptune. This has only been possible for the past 20 years or so,” confirms another study co-author, Lee Fletcher, Professor at the University of Leicester.
About one-third of all recordings were made with the VLT Imager and Medium Infrared Spectrometer (VISIR) in the Atacama Desert, Chile. Thanks to the telescope’s large mirror and high operational altitude, the instrument provides high-resolution data of very high quality, and this set of instruments produces the most accurate images available on the planet Neptune. The researchers also used images from NASA’s Spitze telescope, the Gemini South telescope in Chile, and the Subaru, Keck and Gemini North telescopes in Hawaii.
Astronomers have not yet been able to explain their unexpected observations. It is conceivable that chemical changes in Neptune’s stratosphere, and possibly random weather events, or even a solar correction cycle may underlie this phenomenon. In order to find out the causes of temperature changes, it is certain that the monitoring program must continue for years and decades. Future larger telescopes, such as the ESO Extra Large Telescope (ELT), will be able to detect changes in the planet’s temperature in greater detail and accuracy, while the NASA/ESA/CSA James Webb Space Telescope will be able to detect the atmosphere Atmosphere of Neptune. It will also be able to map chemical composition and temperature more accurately than ever before.
I think Neptune as a whole is a very interesting topic, because we know so little about it.” Roman closes his thoughts. – Our results indicate a more complex atmospheric system and Neptune time variations. “
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