” I was shocked by how rapidly clouds vanished on Neptune,” stated Imke de Pater, emeritus professor of astronomy at UC Berkeley and senior author of the study. “We essentially saw cloud activity drop within a few months.”
As shown by this compilation of images at 1.63 µm (microns) obtained with the NIRC2 and adaptive optics system on the Keck II Telescope, Neptune had various cloud features organized in latitudinal bands from before 2002 through late 2019. Later on, clouds appeared practically absent except near the south pole.
” Even 4 years later, the images we took this previous June revealed the clouds have not returned to their previous levels,” stated Erandi Chavez, a graduate student at Harvard Universitys Center for Astrophysics who led the research study when she was an undergraduate astronomy trainee at UC Berkeley. “This is unexpected and incredibly interesting, particularly considering that Neptunes previous duration of low cloud activity was not nearly as dramatic and extended.”
Techniques of Tracking Neptunes Clouds
To monitor the advancement of Neptunes look, Chavez and her group examined images drawn from 1994 to 2022 using Keck Observatorys second generation Near-Infrared Camera (NIRC2) paired with its adaptive optics system (given that 2002), along with observations from Lick Observatory (2018-2019) and the Hubble Space Telescope (considering that 1994). Recently the Keck Observatory observations have actually been complemented by images taken as part of Keck Observatorys Twilight Observing Program and by Hubble Space Telescope images taken as part of the Outer Planet Atmospheres Legacy (OPAL) program.
Solar Cycle and Neptunes Clouds
The data exposed an interesting pattern in between modifications in Neptunes cloud cover and the solar cycle– the duration when the Suns magnetic field turns every 11 years, triggering levels of solar radiation to fluctuate. When the Sun discharges more intense ultraviolet (UV) light, particularly the strong hydrogen Lyman-alpha emission, more clouds appear on Neptune about 2 years later. The group further discovered a positive correlation in between the variety of clouds and the ice giants brightness from the sunshine reflecting off it.
” These exceptional data provide us the greatest proof yet that Neptunes cloud cover correlates with the Suns cycle,” said de Pater. “Our findings support the theory that the Suns UV rays, when strong enough, might be activating a photochemical response that produces Neptunes clouds.”
This series of Hubble Space Telescope images chronicles the waxing and subsiding of the amount of cloud cover on Neptune. The Hubble observations along the top, clearly reveal a connection in between cloud abundance and solar peak of activity. The chemical changes are caused by photochemistry, which occurs high in Neptunes upper environment and takes time to form clouds.
The connection in between the solar cycle and Neptunes cloudy weather condition pattern is stemmed from 2.5 cycles of cloud activity recorded over the 29-year period of Neptunian observations. Throughout this time, the planets reflectivity increased in 2002 (brightness optimums), then dimmed (brightness minima) in 2007, ended up being intense once again in 2015, then darkened in 2020 to the most affordable level ever observed, which is when the majority of the clouds disappeared. The modification in Neptunes brightness triggered by the Sun appears to go up and down reasonably in sync with the going and coming of clouds in the world.
More work is necessary to unload this correlation provided the complexity of other aspects; for example, while an increase in UV sunlight could produce more clouds and haze, it might likewise darken them, therefore reducing Neptunes total brightness. Storms on Neptune rising from the deep environment affect the cloud cover, however are not connected to photochemically-produced clouds, and for this reason might complicate correlation studies with the solar cycle. Continued observations of Neptune are likewise needed to see the length of time the existing near-absence of clouds will last.
Neptunes Chaotic Atmosphere.
This discovery adds to the exciting observations of the blue-hued worlds chaotic and wildly active environment, which feature methane clouds that are whipped around by supersonic winds– the fastest wind speeds tape-recorded throughout our planetary system. Among the earliest and most striking images was caught by NASAs Voyager 2 spacecraft during its flyby of Neptune in 1989, exposing a massive storm system called the “Great Dark Spot.” Other storms and dark spots have been found because, in specific a large equatorial storm in 2017 and a large dark spot at northern latitudes in 2018.
” Its interesting to be able to use telescopes on Earth to study the climate of a world more than 2.5 billion miles far from us,” stated Carlos Alvarez, personnel astronomer at Keck Observatory and co-author of the study. “Advances in technology, as well as our Twilight Observing Program, have enabled us to constrain Neptunes atmospheric models, which are key to comprehending the correlation in between the ice giants environment and the solar cycle.”.
Ongoing Research and Future Investigations.
The research group continues to track Neptunes cloud activity. The recent images taken in June 2023 were gotten at the very same time as when NASAs James Webb Space Telescope (JWST) recorded near- and mid-infrared images.
” We have actually seen more clouds in the most current images, in specific at northern latitudes and at high altitudes, as anticipated from the observed increase in the solar UV flux over the previous ~ 2 years,” said de Pater.
The combined data from JWST and Keck Observatory will make it possible for further examinations into the physics and chemistry that causes Neptunes vibrant look, which in turn might help deepen astronomers understanding not just of Neptune, but likewise of exoplanets.
For more on this discovery, see Neptunes Disappearing Cloud Mystery: Astronomers Discover a Solar Connection.
Recommendation: “Evolution of Neptune at near-infrared wavelengths from 1994 through 2022” by Erandi Chavez, Imke de Pater, Erin Redwing, Edward M. Molter, Michael T. Roman, Andrea Zorzi, Carlos Alvarez, Randy Campbell, Katherine de Kleer, Ricardo Hueso, Michael H. Wong, Elinor Gates, Paul David Lynam, Ashley G. Davies, Joel Aycock, Jason Mcilroy, John Pelletier, Anthony Ridenour and Terry Stickel, 9 June 2023, Icarus.DOI: 10.1016/ j.icarus.2023.115667.
A picture of Neptune taken with the Keck II telescope on June 21, 2023, shows nearly no clouds except near the south pole. Credit: Imke de Pater, Erandi Chavez, Erin Redwing (UC Berkeley)/ W. M. Keck Observatory
Neptunes clouds have actually almost disappeared for the very first time in 3 decades. Observations show a prospective link in between the worlds cloud patterns and the solar cycle, regardless of Neptunes large range from the Sun. Continuous research aims to unwind this secret.
For the very first time in nearly 3 decades of observations, clouds seen on Neptune have actually all however disappeared. Images from 1994 to 2022 of the big blue planet recorded from Maunakea on Hawaiʻi Island through the lens of W. M. Keck Observatory, together with views from area by means of NASAs Hubble Space Telescope show clouds are almost gone with the exception southern pole. The observations, which are published in the journal Icarus, further reveal a connection between Neptunes vanishing clouds and the solar cycle– an unexpected discover given that Neptune is the farthest major planet from the Sun and receives just 1/900th of the sunlight we get on Earth.
Cloud Observations and Surprises
A group of astronomers led by the University of California (UC) Berkeley found the abundance of clouds normally seen at the icy giants mid-latitudes began to fade in 2019.
The observations, which are published in the journal Icarus, additional reveal a connection between Neptunes vanishing clouds and the solar cycle– an unexpected find given that Neptune is the farthest major world from the Sun and gets only 1/900th of the sunlight we get on Earth.
As revealed by this compilation of images at 1.63 µm (microns) acquired with the NIRC2 and adaptive optics system on the Keck II Telescope, Neptune had various cloud features arranged in latitudinal bands from before 2002 through late 2019. The data revealed an interesting pattern between changes in Neptunes cloud cover and the solar cycle– the period when the Suns magnetic field turns every 11 years, causing levels of solar radiation to fluctuate. The connection in between the solar cycle and Neptunes cloudy weather condition pattern is obtained from 2.5 cycles of cloud activity recorded over the 29-year period of Neptunian observations. Storms on Neptune rising up from the deep atmosphere affect the cloud cover, but are not related to photochemically-produced clouds, and hence might make complex correlation research studies with the solar cycle.
By W. M. Keck Observatory
August 21, 2023
