The European Southern Observatory's Very Large Telescope is one of the telescopes used to track Neptune's atmospheric temperatures. They found a drop in Neptune's global temperatures followed by a warming at its south pole.
Michael Roman, a research associate at the University of Leicester, UK, is the lead author of a study published today in The Planetary Science Journal.
Like Earth, Neptune has seasons. The Neptune season lasts 40 years, with one year lasting 165 Earth years. Astronomers were eager to see how temperatures were changing after the southern summer solstice, since it has been summertime in Neptune's southern hemisphere since 2005.
Astronomers looked at nearly 100 thermal-infrared images of Neptune, captured over a 17-year period, to piece together overall trends in the planet's temperature in greater detail than ever before.
The data showed that most of the planet had cooled over the last two decades. The average temperature of Neptune dropped between 2003 and the present day.
During the last two years of their observations, the astronomer were surprised to discover a dramatic warming of Neptune's south pole. Neptune's warm polar vortex has been known for a long time, but it has never been observed before on the planet.
The data cover less than half of a Neptune season, so no one was expecting to see large and rapid changes.
The astronomer used thermal cameras to measure Neptune's temperature. The team combined all the images of Neptune gathered over the last two decades by ground-based telescopes. They looked at the light that was emitted from Neptune's atmosphere. The team was able to build up a picture of Neptune's temperature and its variations during the southern summer.
Neptune is a very cold planet and measuring its temperature from Earth is difficult.
Around one third of the images were taken from the VLT Imager and Spectrometer for the VISIR instrument. The clearest images of Neptune can be seen from the telescope because of its mirror size and altitude. The team used data from NASA's Spitzer Space Telescope, as well as images taken with the Gemini South telescope in Chile, as well as with the Subaru Telescope, the Keck Telescope, and the Gemini North telescope, all in Hawai'i.
Neptune's temperature variations were so unexpected that the astronomer don't know what caused them. They could be due to changes in Neptune's chemistry or random weather patterns. There will be more observations needed to explore the reasons for the fluctuations. The NASA/ESA/CSA James Webb Space Telescope will provide unprecedented new maps of the chemistry and temperature in Neptune's atmosphere, while future ground-based telescopes could observe temperature changes like these in greater detail.
Roman says that Neptune is intriguing to many of us because we still don't know a lot about it.
More information: "Sub-Seasonal Variation in Neptune's Mid-Infrared Emission" The Planetary Science Journal (2022). DOI: 10.3847/PSJ/ac5aa4 Journal information: The Planetary Science Journal Citation: Astronomers capture surprising changes in Neptune's temperatures (2022, April 11) retrieved 11 April 2022 from https://phys.org/news/2022-04-astronomers-capture-neptune-temperatures.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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