by If you buy links to our articles, the future and its syndicate partners can earn a commission.
Japan’s Akatsuki spaceship recorded this false-colored image of Venus’ Dayside on March 30, 2018 Credit: Jaxa/Planet-C project team
In a random turn of events, scientists have found that Japan’s Himawari-8- and Himawari-9 weather satellites, which are supposed to monitor storms and climate patterns here on Earth, have also been collecting quiet data about Venus for almost a decade.
Although meteorological satellites circle the earth and scan around the sky around it, their imaging range extends into space, so that they can occasionally catch insights into other heavenly neighbors such as the moon, stars and other planets in our solar system.
“This started by accident,” said Gaku Nishiyama, a post-doctoral researcher at the German Aerospace Center (known under his German acronym DLR) in Berlin in an interview with Space.com. “One of my best friends who has a doctorate in astronomy and is a certified weather forecast in Japan found moon pictures in Himawari-8/9 data sets and asked me to watch.”
At that time, Nishiyama concentrated on moon science, and in an unconventional way he began with the Himawari 8 and HAMAWARI 9 weather satellites that were launched in 2014 and 2016: as space telescopes. By analyzing the light, which the moon emitted in infrared wave lengths, he and his team were able to test the ability of the satellites to capture temperature fluctuations above the lunar surface and to determine its physical properties.
“During this lunar work we also found other solar systems, namely mercury, Venus, Mars and Jupiter, in the data records. We were interested in what the phenomena were recorded there,” said Nishiyama.
In order to recognize Venus in the Himawari data, the team used the exact imaging plan and the position of the satellites. “Because we almost know exactly when and where Himawari looks,” said Nishiyama, “we can roughly predict where Venus will appear in every picture. From there we areolate the pixels that correspond to Venus.”
Nishiyama and his colleagues analyzed subtle changes in the intensity of light Venus. Such data enable scientists to pursue how the brightness of a heavenly body varies over time, which in turn shows details.
The Himawari satellites recorded one of the longest multi -band infrared records of Venus, which were ever gathered. This unique data record reveals subtle changes in the cloud depotes of the planet as well as signs of phenomena, which are called Thermoy Tides and Rossby Waves.
“Thermal tides are global gravity waves that were excited by sun heating in the venus cloud layers,” said Nishiyama. “When the atmosphere is layered, as on Venus (i.e. a warm upper layer on a cold lower layer), a restoring force has a restoring force on heated air packages, and the resulting vertical oscillations spread as a gravity waves. Rossby waves [also seen in Earth’s oceans and atmosphere] are also a wave on a global scale caused by variations of the Coriolis power with latitude.
“Both types of waves are crucial for the transport of heat and dynamics through the atmosphere of Venus,” he continued. “The persecution of how these waves change over time helps us to better understand the atmospheric dynamics of the planet, especially since other data such as wind speeds and cloud reflection have shown that it takes place over several years.
“In particular, we managed to recognize variations in temperature fields, which were caused by Rossby waves at different heights for the first time, which is important for understanding physics behind the years of variations of the venus atmosphere,” said Nishiyama.
These new observations contribute to closing a crucial gap in our understanding of the dynamic upper atmosphere of Venus and opening a new limit in the planetary monitoring from the earth orbit. The results of the team also challenge the calibration of the most important instruments in the special Venus room vehicles, such as the LIR camera on board the Japan’s Akatsuki Venus Orbiter.
“In order to understand the atmospheric structure of Venus, the determination of the temperature in infrared wavelengths is crucial,” said Nishiyama. “Lir was expected to provide precise temperature information. However, LIR has suspended several problems in the instrument calibration.”
Under the comparison of pictures of lir and Himawari satellites at the same time and under identical geometric conditions, the team found discrepancies and suspected that Lir underestimates the radiance of Venus. “Our comparison between Himawari and Lir illuminates how the LIR data can be re -calibrated, which leads to a more precise understanding of the atmosphere of Venus,” said Nishiyama.
Related stories
– Betelgeuses ‘great dimming’ had an unlikely observer: a Japanese weather satellite
– Venus facts: Everything you need to know about the 2nd planet of the sun
– Fascinating satellite video captures a magical view of the earth
The team is also confident that Himawari adds data from missions such as Akatsuki and Bepicolombo, a common Japanese-European mission that is currently being established in the orbit around Mercury. Nishiyama explained that Himawari covers a wider area of infrared wave lengths compared to Akatsuki and provides information at different heights. In contrast to Bepicolombo, which Venus only observed during a Flyby, Himawari can monitor the planet over a much longer period of time.
“Straw observation satellites [like Himawari] are generally calibrated that they can provide reference data for instrument calibration in future planetary missions, “he said. Since meteorological satellites continue the observation for decadical time scales, these satellites can also complement data if no planetary exploration scream screams on planets.”
Nishiyama said the team has already archived other solar systems that are now being analyzed. “We believe that the continuation of such activities will further expand our horizon in the field of planetary science,” he concluded.
The team reported on their results in the magazine Earth, planet and space last month.
