Summer on Neptune: First time to notice surprising temperature fluctuations

Summer on Neptune: First time to notice surprising temperature fluctuations News

An international research team discovered unexpected temperature fluctuations on Neptune using the Very Large Telescope as well as other ground-based telescopes. Global temperatures fell rapidly during a long summer and the South Pole warmed up just as fast. These changes are still mysterious.

Neptune also has seasons, just like Earth. However, the difference lies in the length of summer. While it may last three months on Earth, Neptune’s summer lasts over 40 years on the eighth planet. Monitoring Neptune’s climate changes means that data must be collected over a long period of time. A research team from around the world used various telescopes to observe Neptune’s climate change and came up with some fascinating results.

Summer on Neptune: First time to notice surprising temperature fluctuations

It was possible to examine the changes in temperature during the summer of 2005 using data from 17 years. Even though the information was only half the season, it allowed for changes of nearly 10 degrees in a very short time. The temperature of most planets dropped by 8 degrees between 2003-2018. The South Pole, however, experienced a temperature drop of about 8 degrees between 2003 and 2018. This is in contrast to the South Pole which saw a rise of 11 degrees over two years (2018-2020).

Infrared observations

Researchers expected a slight rise in temperature during Neptune’s hot season, which is similar to what happens on Earth in the summer. Michael Roman, University of Leicester research fellow, was the study’s lead author. He said that the unexpected variations were not expected. Roman’s research aims to examine the trends in planet’s temperature with a variety images that were unavailable before the advent large telescopes.

Thermal infrared images can be used for similar studies. Researchers examined about 100 photos that were collected over 17 years.

Summer on Neptune: First time to notice surprising temperature fluctuations

The VLT telescope was the first telescope to allow for sharp and clear infrared images. It was impossible to measure accurately the temperature of a body at Neptune’s distance, which is approximately 4.5 billion km from Earth. About a third of all images used by astronomers to study Neptune were taken with the Very Large Telescope. These “photos” were actually made with the VISIR instrument (VLT Imager & Spectrometer For Mid-InfraRed). Because of the telescope’s height and size, the resulting images are clearest. Combining these two factors produces very high data quality and resolution.

The Gemini South telescope also contributed to the VLT. It is also located in Chile. Gemini North’s twin was also involved. The other key players were the Subaru telescope in Hawaii and the Keck telescope in Hawaii. Data from NASA’s Spitzer telescope was also used by the team. The future will see the James Webb Space Telescope (JWST) and the Extremely Large Telescope, the next generation telescope at the European Southern Observatory (ESO). JWST will produce unprecedented maps of Neptune’s chemical composition and temperature, while ELT will be able observe temperature fluctuations such as those just described in greater detail. This will allow us to better understand the mechanism that causes large temperature fluctuations in Neptune’s climate.

These temperature fluctuations are caused by what?

Scientists are still unable to explain why temperature fluctuations occur on this distant planet. There are two possible explanations: changes in Neptune’s chemical composition and random weather patterns. These changes can also be influenced by the solar cycle which lasts approximately 11 years. To solve the puzzle, data collection must continue for the next few years. This will allow us to capture as much as the Neptunian season possible using high-resolution images we have not taken before.


Alexander Stephenson

Candidate of Chemical Sciences, editor-in-chief of Lecturer at several international online schools, member of the jury of chemistry competitions and author of scientific articles.

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