Summary
As Sunspots Come and Go, So Does the Cloudy Weather on the Blue Giant Planet
Weather forecast for Neptune: After sunny weather for the past few Earth years, we’ll see increasingly more clouds over the next few years.
In 1989, NASA’s Voyager 2 spacecraft provided the first close-up images of linear, bright clouds, reminiscent of cirrus clouds on Earth, seen high in Neptune’s atmosphere. They form above most of the methane in Neptune’s atmosphere and reflect all colors of sunlight, which makes them white.
On that frozen frontier the Sun is still influential regarding the Neptunian weather that produces cloud cover. At Neptune’s distance of nearly 3 billion miles, the Sun appears starlike at 1/30th the diameter of the full Moon. This feeble radiation is 1% the amount of starlight as received on Earth.
Yet the Sun’s influence on Neptune became increasingly obvious when astronomers looked at 30 years of Neptune observations with the Hubble and Keck telescopes. Neptune’s abundance of clouds waxes and wanes over an 11-years cycle. The Sun also has an 11-year cycle where it becomes stormy as its magnetic fields become entangled, increasing sunspot number and rate of violent outbursts.
Full Story
Astronomers have uncovered a link between Neptune’s shifting cloud abundance and the 11-year solar cycle, in which the waxing and waning of the Sun’s entangled magnetic fields drives solar activity.
This discovery is based on three decades of Neptune observations captured by NASA’s Hubble Space Telescope and the W. M. Keck Observatory in Hawaii, as well as data from the Lick Observatory in California.
The link between Neptune and solar activity is surprising to planetary scientists because Neptune is our solar system’s farthest major planet and receives sunlight with about 0.1% of the intensity Earth receives. Yet Neptune’s global cloudy weather seems to be driven by solar activity, and not the planet’s four seasons, which each last approximately 40 years.
At present, the cloud coverage seen on Neptune is extremely low, with the exception of some clouds hovering over the giant planet’s south pole. A University of California (UC) Berkeley-led team of astronomers discovered that the abundance of clouds normally seen at the icy giant’s mid-latitudes started to fade in 2019.
“I was surprised by how quickly clouds disappeared on Neptune,” said 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,” she said.
“Even now, four years later, the most recent images we took this past June still show the clouds haven’t returned to their former levels,” said Erandi Chavez, a graduate student at the Center for Astrophysics | Harvard-Smithsonian (CfA) in Cambridge, Massachusetts, who led the study when she was an undergraduate astronomy student at UC Berkeley. “This is extremely exciting and unexpected, especially since Neptune’s previous period of low cloud activity was not nearly as dramatic and prolonged.”
To monitor the evolution of Neptune’s appearance, Chavez and her team analyzed Keck Observatory images taken from 2002 to 2022, the Hubble Space Telescope archival observations beginning in 1994, and data from the Lick Observatory in California from 2018 to 2019.
In recent years, the Keck observations have been complemented by images taken as part of the Twilight Zone program and by Hubble’s Outer Planet Atmospheres Legacy (OPAL) program.
The images reveal an intriguing pattern between seasonal changes in Neptune’s cloud cover and the solar cycle – the period when the Sun’s magnetic field flips every 11 years as it becomes more tangled like a ball of yarn. This is evident in the increasing number of sunspots and increasing solar flare activity. As the cycle progresses, the Sun’s tempestuous behavior builds to a maximum, until the magnetic field beaks down and reverses polarity. Then the Sun settles back down to a minimum, only to start another cycle.
When it’s stormy weather on the Sun, more intense ultraviolet (UV) radiation floods the solar system. The team found that two years after the solar cycle’s peak, an increasing number of clouds appear on Neptune. The team further found a positive correlation between the number of clouds and the ice giant’s brightness from the sunlight reflecting off it.
“These remarkable data give us the strongest evidence yet that Neptune’s cloud cover correlates with the Sun’s cycle,” said de Pater. “Our findings support the theory that the Sun’s UV rays, when strong enough, may be triggering a photochemical reaction that produces Neptune’s clouds.”
Scientists discovered the connection between the solar cycle and Neptune’s cloudy weather pattern by looking at 2.5 cycles of cloud activity recorded over the 29-year span of Neptunian observations. During this time, the planet’s reflectivity increased in 2002 then dimmed in 2007. Neptune became bright again in 2015, then darkened in 2020 to the lowest level ever observed, which is when most of the clouds went away.
The changes in Neptune’s brightness caused by the Sun appear to go up and down relatively in sync with the coming and going of clouds on the planet. However there is a two-year time lag between the peak of the solar cycle and the abundance of clouds seen on Neptune. The chemical changes are caused by photochemistry, which happens high in Neptune’s upper atmosphere and takes time to form clouds.
“It’s fascinating to be able to use telescopes on Earth to study the climate of a world more than 2.5 billion miles away from us,” said Carlos Alvarez, staff astronomer at Keck Observatory and co-author of the study. “Advances in technology and observations have enabled us to constrain Neptune’s atmospheric models, which are key to understanding the correlation between the ice giant’s climate and the solar cycle.”
However, more work is necessary. For example, while an increase in UV sunlight could produce more clouds and haze, it could also darken them, thereby reducing Neptune’s overall brightness. Storms on Neptune rising up from the deep atmosphere affect the cloud cover, but are not related to photochemically produced clouds, and hence may complicate correlation studies with the solar cycle. Continued observations of Neptune are also needed to see how long the current near-absence of clouds will last.
The research team continues to track Neptune’s cloud activity. “We have seen more clouds in the most recent Keck images that were taken during the same time NASA’s James Webb Space Telescope observed the planet; these clouds were in particular seen at northern latitudes and at high altitudes, as expected from the observed increase in the solar UV flux over the past approximately 2 years,” said de Pater.
The combined data from Hubble, the Webb Space Telescope, Keck Observatory, and the Lick Observatory will enable further investigations into the physics and chemistry that lead to Neptune’s dynamic appearance, which in turn may help deepen astronomers’ understanding not only of Neptune, but also of exoplanets, since many of the planets beyond our solar system are thought to have Neptune-like qualities.
The findings are published in the journal Icarus.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.
About This Release
Credits
Release
NASA, ESA, STScI, UC Berkeley, Keck Observatory
H/T John C, Nick R
I’ve peeked at Neptune a few times this summer. In my C14 (350mm aperture), it’s a tiny faint blue dot, about four diffraction discs wide, like a fat low surface brightness star. It looks so remote it always affects my mood. Small changes like this are far too subtle for a earthbound scope like mine being used in an ordinary fashion. But I wonder if the variation in abedo could be teased out of a stream of images by someone well versed in image processing?
I did do something this summer I’ve always wanted to do – I hunted down and positively identified Pluto! A 14th magnitude speck in a field of specks. A distinctive speck pattern though.
Yes, Randle Neptune is a nice sight. We often show our guests at Stargazers Astronomy Tours in NZ this planet and it’s even obvious to novices that it has a definite blue tinge and is much wider than any star through our C14 on the CGE Pro mount. Always interesting to compare it with Uranus which is quite a bit bigger but with a similar colour. Never bothered to seek out Pluto though.
Alastair
I have the same C14/CGE-Pro rig. I have it up at my cabin in dark sky site in the South Sierra mountains. Dark sky for us. But well I remember the night sky in the middle of the south pacific.
Here is the website and tracker I used – I like this site. If you don’t have the time to plot it on multiple nights, it’s helpful to view at a time when Pluto is in a distinctive formation with a double or triple star.
Dwarf Planet Pluto Real Time Position Tracker | TheSkyLive.com
Another little project of mine is to join the “Billion Light Year Club”. Which means viewing a quasar. Those are all >7 billion LY away and are about >14+ magnitude. I tried one night and got blown out of the water. I saw lots of specks, but which one was the quasar I couldn’t tell. It will need a bit more prep.
This newly discovered solar cycle Neptune ‘cloud’ influence is interesting science, but does not extrapolate to Earth’s very different atmosphere.
And the Maunder Minimum caused LIA theory that occasionally crops up is sketchy at best. The early sunspot data is worse than funky. And, the purported solar cycle causality doesn’t explain the preceding MWP.
Also being sure that present or observations mean anything would require historical data that does not exist. Neptune was not identified until about 1850?
My thinking is not to extrapolate the changes on Neptune to Earth, as the atmospheres are not the same as you say. However, and to me this is the significance of this paper, is that the solar output varies by only 1% between minimum and maximum, and is deemed to be insufficient to have a major effect on earth’s climate. Yet here is evidence that that 1% change is sufficient to impact the atmosphere of a planet 30 times further from the sun in a way that is observable. What impact would this have on our upper atmospheric chemistry? What mechanisms might exist to transfer those changes from the upper atmosphere to the lower levels?
What also gets mentioned is the Galactic cosmic ray theory of cloud formation.
It is only a 0.1% change in total energy with the solar cycle.
It is called the “top-down” mechanism, first proposed by Joanna Haigh in the 1990s and since demonstrated to the point that the IPCC accepts its existence in AR5.
It’s funny how a 1% change in something which constitutes 99% of the mass of the system is considered “small”, from the perspective of something which is 3 millionths smaller in mass.
The variability in UV is far greater than in TSI. UV is qualitatively different from less energetic spectra. It makes and breaks ozone and splits water into O and H atoms and molecules, among other climatic relevant affects.
I’ve sussed it: Nitrogen did it.
First, see the attached: “Anasazi”
And the MWP: Anasazi drove themselves (almost literally) off a cliff and in doing so the created the MWP
IOW: Around that time they finally finished chopping all the trees and overgrazing the resultant grasslands in their corner of the world and so created the desert we see now.
At that relatively low latitude, trees work to keep the landscape cool so when the trees went, a huge everlasting ‘inland El Nino‘ was triggered – and we all know how Nino affects the whole globe.
That global warmth being compounded and as we witness with Hurricane Hilary right now, by an immense amount of dust, wind-borne and water-borne, being flushed out into the ocean. Sol then heated the upper layers of the Eastern Pacific water more than normal and so set off ‘vigorous weather‘ which moved that heat around the world.
The LIA: Just like the Anasazi, this was triggered by cutting & burning of trees – this time by a sugar-addicted thus belligerent and warmongering King Henry 8th. He needed the trees for charcoal to make cannons and cannonballs.
Of course the folks on the receiving end of Henry’s fire felt obliged to return it so they chopped vast amount of their (NW European) forest.
But unlike the Anasazi, at that much higher latitude trees keep you warm so Henry’s action triggered a long-lasting La Nina = what we now call the LIA and it dispersed itself around the globe. Nice.
Sunspot Minimum and escape from LIA
Herein was/is a very unfortunate coincidence = that when the forest wanted to recover itself after he was dead/gone and peace had broken out – the wannabe forest found itself short of an essential nutrient as it tried to grow back
Because of the quiet sun = the Maunder Minimum.
Never mind the Total Solar Irradiance, if you are in any way dependant on Sol’s UV output, you find yourself lurching from feast to famine.
UV output varies massively, Sol really is a ‘UV Candle in the Wind‘
And what the UV was doing, still is, it converts diatomic Oxygen to tri-atomic Ozone
That threesome is a very unhappy marriage and rapidly (temp/pressure depandant) falls apart creating extremely vicious little shits in the shape of Oxygen Free Radicals
And they will oxidise Nitrogen.
This makes Nitrogen become water soluble = available to plant, and especially bacterial, life.
Water soluble Nitrogen is THE Liebig Limiter for all land based life
That is what caused the LIA to end.
Basically, the sun came out but not as we see it.
The sun came out in the UV spectrum.
That made Ozone which made Nitrogen which made trees which (at high latitudes) made the weather warm up.
So yes it was a Cause & Effect but also, an incredible coincidence, in that Henry chopped the trees at the same time Sol went quiet.
edit to wonder:
Who’s making my pictures so fuzzy?
No matter, see them in full technicolour glory with <Right click > Open in New tab>
And haven’t I just destroyed that ever so twee assertion concerning “Where did Life on Earth come from?”
The contemporary answer being that ‘It arrived on comets falling into/onto an early Earth‘
That’s perfect garbage of course because it avoids the question of ‘Where did comets get the life from?’
Absolutely crazy innit = that The Most Chemically Destructive Things we know, Oxygen Free Radicals, might have powered the chemistry that made Life on Earth.
They themselves created from the most destructive/toxic form of radiation that Sol creates = Ultra Violet.
haha: Life is (a shade of) Purple – not = Green
You cannot accuse Gaia of not having a sense of humour now can you
Your ignorance of the Anasazi is profound.
A) Anasazi planted maize (corn as it was back then) Native American style.
i) That is, they scratched the earth in one spot and planted three plants, maize, beans and squash. They planted entire fields this way. NO TILLING!!!
Corn provides the stalk for beans to climb and squash provide shade that helps keep moisture in the soil.
ii) The “Mesa” tops are high enough in altitude that winters are harsh. Even today after a couple centuries of neglect are relatively free of big trees. Lots of scrub bush/trees which make for deadly forest fires.
iii) The Anasazi developed/used a corn that was capable of sending a germinating seed’s tap root 12 inches (305mm) deep in search of water. A very unusual plant.
iiii) Where the Anasazi lived is known as “Arid” land! That is, desert!
v) The Anasazi lived in cliff side dwellings that used shallow handhold/footholds on sheer cliff faces!
Anasazi crops were grown on the Mesa top, not down in the valleys between Mesas. Enemies starved the Anasazi by holding/burning the crops.
Rubble below some Cliff Side dwellings have revealed human bones with cut marks which are considered evidence of cannibalism.
vi) Drought is/was NOT CAUSED by Anasazi tilling the Earth as they did not till the Earth! Their methods of planting were very low Earth disturbance!
Mayans in South America lived amongst lush jungles and farms and were also brought low by extended droughts. Droughts linked to El Nino and South Atlantic oscillations.
Recent studies that claim logging helped cause drought all appear to be loose claims based upon personal bias and beliefs. The Maya environment grows jungle just a few years after mankind ceases keeping the jungle out of where they live.
My family and I visited Four Corners for a full week one year.
On another trip we visited Cliff dwellings not far from Sunset Crater in Arizona. A long distance from Four Corners.
As one takes the trail to the cliff dwellings, with the trail sign is a warning about mountain lions. Then one can walk amongst the ruins and see handprints and fingerprints where roofs protect the mud mortar. Roofs are constructed of logs from the mountains and mud.
Mud mortar is quickly washed out by any rainfall. Like the adobe (mud) dwellings, they exist because the environment is very arid!
Although the atmosheres are very different and so the mechanisms cannot be extropolated from Neptune to Earth… the fact that any mechanism can be seen at all is interesting.
The Sun doesn’t vary that much as a proportion of its output (OK, it’s output is big). But it does vary in an 11 ear cycle and, lo and behold, here is another 11 year cycle.
Or is it?
30 years of observations to find an 11 year cycle does not provide many datapoints.
Let’s wait and see.
Heinrich Schwabe discovered the 11-year solar cycle with 17 years of data. Not even two full periods.
UV light provide energy to assist chemical changes.
I suspect the clouds might depend upon solar wind particles as much as UV chemistry.
So far, it is a greatly simplified correlation. Causation suggestions is/are personal opinions and bias rather than science.
It does extrapolate in one aspect. For Neptune, the solar cycle still means a 0.1% variation in TSI and a 3% variation in UV, and UV is still only 1% of TSI. And Neptune gets 0.1% of the TSI that the Earth gets. So we are talking about negligible changes in energy over a much smaller amount of total energy.
Yet these insignificant changes are capable of causing significant changes in Neptune’s atmosphere, just as they do in Earth’s atmosphere.
It is not the amount of energy, my friend. It is where it is delivered and what effect it has there. In both cases, the UV energy – the one that really changes with the solar cycle – is delivered higher in the atmosphere than the rest, where the density is much lower and the effect is much greater. In the case of the Earth, it is the ozone layer, 22-35 km high.
Your assumptions, like almost everyone else’s, about how solar variability should affect climate are wrong. It alters stratospheric temperature gradients by altering the stratospheric circulation. That circulation is not powered by the sun. It is powered by atmospheric waves whose behavior changes with solar activity. This was proposed in 1974 and demonstrated since. The effect involves so much energy that the Earth’s rotation rate responds to the solar cycle. This change in energy is provided by the changing behavior of the atmospheric waves, not by the small change in solar energy.
Neptune’s cloud changes are a nice support for how solar variability affects climate.
Exactly.
Furthermore, Neptune’s apehelion is 4.559e9 km and its perihelion is 4.471e9 km. This distance variation from the Sun would result in a (4.559/4.447)^2 = 1.040 = 4% variation of TSI at Neptune just due to orbital eccentricity . . . 40 times greater than the Sun’s absolute luminosity variation over any max/min sunspot half-cycle.
However, the orbital period of Neptune is about 164 years, so the 30 years of cloud observations referenced in the above article reflects about (30/(164/2))*4 = 1.46% change in TSI just due to orbital motion, still more than an order-of-magnitude greater than the TSI variation over an ~11 year solar sunspot cycle.
Neptune will reach its next perihelion passage in mid-2044.
I say that 600 million tons of hydrogen per second can’t be wrong.
The Suns effect on planetary climate cannot be dismissed out of hand – it is a plausible driver of the earths climate and, as the science is far from settled, must continue to be investigated
The cycle of the Suns radiation strength that causes those changes on Neptune also cause at least 30 times as much change in the Earth’s atmosphere. It is demonstrated by any Armature Radio Operator (Ham). For over 60 years I have seen extreme changes in the ability to communicate with different countries directly correlated with the changes in the Sun.
For Example, I live in Central USA, For the entire month of January, I was unable to hear any Ham on 10 Meters (28 MHz). The band was dead – Quiet. It was as if the Antenna cable had been disconnected or cut. I could hear nothing even with the gain and Volume at max. Today, the 80 Meter band gives me the same problem for all but about two hours at about 09:00 UTC. The upper atmosphere definitely changes with the number and strength of the sunspots. Also, the solar flares obviously, eject stronger/higher energy particles and different particles. Look at the Aurorae, obviously they change the upper atmosphere.
What do these Sun Flares do to H2, O2, O3, He, CO2, N2, H20, Fluorocarbons?
Solar maxima and minima do indeed explain the Medieval WP as well as the LIA CP. Sunspot observations since c. AD 1600 are supported by radioisotope data.
Medieval WP: one shallow solar minimum.
LIA CP: four deeper minima, ie Wolf, Spoerer, Maunder and Dalton.
https://en.wikipedia.org/wiki/Sp%C3%B6rer_Minimum#/media/File:Carbon14_with_activity_labels.svg
Followed by Modern Maximum, coming out of the LIA minima.
CO2 need not apply. It’s an effect, not an original cause.
Who knew there is a lick observatory?
Its used by cats to check out the Milky Way.
That could explain all the flying saucer sightings.
Yeah, a simple misstep can send saucers flying.
This is the type of factual science that supports the long held theory that our Sun is the main driver of earths climate, not puny humans and their 200 years of industrial growth – it needs much more investigation so we know, beyond all doubt, what the correlation is
Expecting to find a single cause is why this field has got nowhere in last 70 years.
CO2 has an effect , sun has an effect, moon has an effect plus it is a chaotic non linear system which does weird shit all the time to confound simplistic attempts are linearising everything and expecting direct correlation.
Looks like another NASA “diversity” hire. No idea about science , incapable of seeing such glaring contradictions, but score strongly on immutable characteristics index.
10:1 is the new rounding error. Well within the range of the typical NASA press release.
There are two quantities – “The feeble radiation” and “intensity”. Not the same thing. I read radiation as the total sun energy received. The projected collection area of Neptune is about 15 times the Earth’s. So, very roughly speaking, 0.1% times 15 is 1%.
I think the actual intensity is about 0.13%
Any source that emits energy, whether it be a hot sun or a radio antenna has a property where the energy received at a distance falls off as a function of a square of the distance. So if the radiation is 1%, then so is the amount of sunlight.
Also, if the diameter is approximately 1/30th, (compared to the Earth’s), then the radiation, due to the apparent area of the sun in the sky, should drop by about 1/900th. So the 0.1% is probably closer to reality.
Simple scaling.
Intensity scales to the inverse square distance to the sun, if we assume the sun is a point source. Earth is 1 AU. Neptune is 30 AU. So, it’s 1/29^2 = 0.0012 = 0.12%
Collection area just scales to the ratio of the squares of the planet diameters.
30,598^2/7925^2 = 14.9
Neptune has 14.9 times the earth collection area, but only gets 0.12% sun intensity. The product is 14.9*0.0012 = 0.018
So really, about 2%
I’m not accounting for albedo or any assumptions/factors astronomers use.
The inverse square rule is for point sources. It’s a bit more complicated for extended sources. A real radiometric calc would include the solid angles for the source and the receiver. In this case there would be very little difference.
OK, I’m going to do this again. I left off a bit of preface, and I made a small math error.
In regard to what the NASA person wrote.
This was a comparison of the energy received at Neptune compared to Earth. Earth is unity for both intensity and collection area. The Sun can be considered a point source for both Earth and Neptune
Sunlight intensity at Neptune
1AU^2/30AU^2= 0,0011
Collection area
Earth is unity
30598miles/7925miles = 3.86 3.86^2 = 14.9
Sunlight received at Neptune compared to Earth
0.0011*14.9 = 0.0166 ~ 2%
In radiometry being off by a factor of two is considered doing pretty well. I don’t know where the 1% comes from except a round down. I think I would have said “about 1.6%”
So changes in solar UV can affect Neptune at 30 au but not the Earth’s climate.
From the above article:
“Astronomers have uncovered a link between Neptune’s shifting cloud abundance and the 11-year solar cycle, in which the waxing and waning of the Sun’s entangled magnetic fields drives solar activity.
This discovery is based on three decades of Neptune observations captured by NASA’s Hubble Space Telescope and the W. M. Keck Observatory in Hawaii, as well as data from the Lick Observatory in California.”
Excuse me, but that uncovered link is dubious at best. The last 30 years (i.e., since 1993) does not encompass even three full solar sunspot cycles (see accompanying graph). Given that, what is the probability of the so-called link being nothing more than a statistical coincidence?
Also, does Neptune’s percentage of cloud cover vary in an approximate sinusoidal pattern, as would be expected if it was indeed caused by the approximately sinusoidal variations over time that are characteristic of the solar sunspot cycle. Hard to say without a comparison of the two cycles being presented.
Bottom line: IMHO, this looks like a rush to publish.
As a follow-up to my own post, there is also this to consider:
“Neptune has at least 14 moons and six known narrow rings. Each of the myriad particles that constitute the rings can be considered a tiny moon in its own orbit. The four moons nearest the planet orbit within the ring system, where at least some of them may interact gravitationally with the ring particles, keeping them from spreading out.”
— https://www.britannica.com/place/Neptune-planet/Neptunes-moons-and-rings
The attached table listing Neptune’s currently-know moons and their various orbital parameters (especially orbital periods) is from the same URL given above.
Just looking at the range of orbital periods (and that some moons even orbit retrograde), the wide range of orbital inclinations, and the wide range of orbital eccentricities, I don’t have any problem whatsoever concluding that gravitational “resonances” occurring among the various orbiting moons might have a strong, ~11 year period component.
Such would be much more plausible as affecting Neptune’s atmosphere (and cloud formation) than would the very minuscule variations in solar energy received at Neptune’s distance from the Sun that could arise from the Sun’s luminosity variation with sunspot cycle.
It would take a good multi-body orbital analysis program to search for such an ~11-year resonance considering all 14 Neptunian moons simultaneously . . . I’m just wondering if this can be/has been done?
Ooops . . . here’s the table of Neptune’s moons that I referenced in my preceding post: