Neptune, the farthest from the Sun in our solar system, has a reputation for being a mysterious world, after a dramatic drop in atmospheric temperature over the past two decades, astronomers report.

Neptune’s focus on the planet’s stratosphere – a relatively stable region of the atmosphere above the turbulent layer that begins at the level of the crust, where normal climatic phenomena occur – scientists hope to observe rising temperatures in Neptune’s view. Earth places summer in its southern hemisphere, a season that lasts for four decades on this planet. Instead, they found that the temperature in that area was significantly lower.

The study was based on more than 95 infrared thermal images taken with telescopes in Hawaii and Chile from 2003 to 2020, most of which were captured by the Very Southern Telescope (VLT) controlled by the European Southern Observatory (ESO). This is the most in-depth analysis of Neptune’s atmospheric temperature.

“Neptune’s atmosphere seems more complex than we might have imagined, and it seems like a general lesson, not surprising, that it teaches naturalists once again,” said researcher Michael Roman. Postdoctoral Fellow and lead author of the University of Leicester, England. The study was published Monday in the journal Planetary Science.

During the 17 years of study, the temperature in Neptune’s stratosphere dropped by 8 C to -117 C. In contrast, Neptune’s temperature in the troposphere – the lower layer of the atmosphere, which reaches Earth and is even colder – remained at -223 degrees Celsius and showed no significant variation.

Neptune was the least explored of the eight planets in the Solar System, as its large distances are difficult to study from Earth. NASA’s Voyager 2 spacecraft is the only man-made spacecraft to “visit” Neptune in 1989.

“I think Neptune is very interesting to many of us because we know very little about it,” said Michael Roman.

Temperature changes were unevenly distributed with local variations. The southern tropics cooled and then warmed up to cool again. Temperatures in mid-latitudes are initially stable and gradually decrease. Temperatures at the South Pole initially dropped slightly, then warmed dramatically between 2018 and 2020.

“I suspect that global warming is caused by changes in atmospheric chemistry, which respond to seasonal changes in sunlight and affect the way the atmosphere cools,” the study coordinator added.

The average diameter of the planet Neptune is about 49,250 km, which is four times the size of Earth. Neptune orbits the Sun at an average distance of 4.5 billion km, 30 times the distance from Earth, and takes 165 Earth years to orbit the Earth in one orbit. Orbit the Sun – one Neptune year.

The dwarf planet Pluto orbits the Sun at greater distances, but its oval orbit sometimes brings it closer to the star than Neptune.

Neptune and its neighbor Uranus are in the category of giant icebergs like the gas giants Jupiter and Saturn. Neptune, which has no solid surface like the planets mentioned above, has a highly dynamic atmosphere, consisting mainly of hydrogen and helium, with a small amount of methane above the mantle of ammonia and water, forming a nucleus solid. Neptune is the strongest wind of all the planets in the Solar System.

Glenn Orton, co – author of Planetary Science Researcher at the Jet Propulsion Laboratory at the California Institute of Technology (Caltech), said that Neptune could provide scientists with valuable information about extrasolar planets.

“Neptune’s close relationship with a major segment of the exoplanet population means that we may have an exoplanet in our backyard,” Glenn Orton said, referring to the perimeter of the solar system. “It’s probably a planet at the cold end of this spectrum, but Neptune is a model for what could be seen in the future in the meteorology of many exoplanets,” he added.

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