Astronomers document surprising changes in Neptune’s temperatures

The ESO telescope captures dramatic changes in Neptune’s temperatures

This composite shows hot images of Neptune taken between 2006 and 2020. The first three images (2006, 2009, 2018) were taken with the VISIR device on ESO’s Very Large Telescope and the 2020 image in captured by the COMICS user on the Subaru Telescope (VISIR did not work in mid -2020 due to illness). After the Earth has slowly cooled, the South Pole has warmed up in recent years, as shown by a light spot under Neptune in images from 2018 to and 2020. Available: ESO / M. Roma, NAOJ / Subaru / COMICS

A global team of astronomers has used telescopes around the world, including the European Southern Observatory’s Very Large Telescope (ESO’s VLT), to monitor Neptune’s atmospheric temperatures over the past 17 years. They experienced a dramatic drop in the temperature of Neptune’s earth followed by a massive warming at its southern pole.

“This change is not expected,” said Michael Roman, a postdoctoral research fellow at the University of Leicester, UK, and lead author of the study published today in The Journal of Planetary Science. “Because we were watching Neptune in its early southern summer, we thought the temperature would grow slowly, not cold.”

Like Earth, Neptune sees the seasons as it orbits the Sun. However, the Neptune time period is 40 years long, with one Neptune year being 165 earth years. This has been summer on the southern side of Neptune since 2005, and astronomers have been eager to see how the temperature changes after the southern summer solstice.

Astronomers have looked at about 100 thermal-infrared images of Neptune, captured over 17 years, to gather all aspects of Earth’s temperature in greater detail than ever before. before.

Neptune is colder than we thought: Study shows unexpected changes in air temperature

The changes can be seen in Neptune’s hot-infrared radiation, which measures the temperature in Neptune’s atmosphere. The concept shows the relative change in hot-infrared radiation from Neptune’s stratosphere with time for universal images taken by Earth’s telescopes. Flash images are defined as temperature. Thermal-infrared images (above) at wavelengths of 12 μm show Neptune’s presence in 2006, 2009, 2018 (viewed by the European Southern Observatory’s Very Large Telescope’s VISIR instrument), and 2020 (maintained by Subaru’s COMICS player). The South Pole has warmed up in recent years. Yes: Michael Roman / NASA / JPL / Voyager-ISS / Justin Cowart.

These data show that during the entire southern summer, most of the world has been cold for the past two years. The average temperature of Neptune dropped to 8 ° C between 2003 and 2018.

Observers are amazed to see that Neptune’s southern pole has warmed over the past two years, with temperatures rising rapidly to 11 ° C between 2018 and 2020. Although Neptune’s warm polar vortex has been known for many years, it is polar fast. Global warming has never been seen before.

“Our data covers less than half of Neptune’s time, so no one expected to see big and rapid changes,” said lead author Glenn Orton, senior research scientist at Caltech’s Jet. Propulsion Laboratory (JPL) in the US.

Astronomers have measured Neptune’s temperature using temperature sensors that work by measuring the infrared light emitted from the stars. For their evaluation, the company combined all the images of Neptune collected over the past two years by Earth telescopes. They studied infrared light emitted from a space in Neptune’s atmosphere called the stratosphere. This allowed the team to build a picture of Neptune’s temperature and its differences during the southern hemisphere.

Neptune is colder than we thought: Study shows unexpected changes in air temperature

Neptune as seen in visible light (center) and heat-infrared wavelengths (north), by 2020. The central image includes many images from the Hubble Space Telescope, and the thermal-infrared image to the right taken from the Subaru Telescope in Maunakea, Hawaii. In thermal-infrared, Neptune’s hot south pole is much brighter than previously seen. Yes: Michael Roman / NASA / ESA / STSci / MH Wong / LA Sromovsky / PM Fry.

Because Neptune is about 4.5 billion kilometers away and very cold, Earth’s average temperature of -220 ° C is not easy to measure its temperature from Earth. “This type of study is only possible with high -intensity infrared images from large telescopes like the VLT that can look directly at Neptune, and these materials have only been available for the last 20 years,” said Leigh Fletcher. , historian, professor at the University of Leicester.

About a third of all images were taken from the VLT Imager and Spectrometer for Medium-InfraRed Instrument (VISIR) on ESO’s VLT in the Atacama desert of Chile. Due to its large glass size and height, it has a high resolution and data quality, providing the clearest images of Neptune. The team also used data from NASA’s Spitzer Space Telescope and images taken with the Gemini South telescope in Chile, as well as the Subaru Telescope, the Keck Telescope, and the Gemini North telescope, all in Hawaii.

Neptune is colder than we thought: Study shows unexpected changes in air temperature

Neptune’s Voyager 2, captured in August 1989. Courtesy: NASA / JPL-Caltech / Kevin M. Gill.

Because Neptune’s temperature is so unpredictable, astronomers don’t know what could be the cause. These may be due to changes in Neptune’s stratospheric chemistry, or features of the regular season, or the solar cycle. We need to look back in the coming years to find out the reasons for these changes. Future Earth -based telescopes such as ESO’s Extremely Large Telescope (ELT) can detect temperature changes like this with much greater detail, while NASA / ESA / CSA James Webb Space Telescope will provide up -to -date maps of the chemistry and temperature in Neptune’s atmosphere.

“I think Neptune is very interesting to most of us because we know very little about it,” Roman said. “This shows a complex picture of Neptune’s atmosphere and how it changes with time.”


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More information:
“Year-Turn of Neptune’s Mid-Infrared Emission Release” The Journal of Planetary Science (2022). DOI: 10.3847 / PSJ / ac5aa4

Directions: Astronomers capture surprising changes in Neptune’s temperatures (2022, April 11) taken on April 11, 2022 from https://phys.org/news/2022-04-astronomers-capture-neptune -temperatures.html

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