How the sun's influence on the remote planet Uranus changes its brightness in the sky

December 22, 2017, University of Oxford
Credit: Shutterstock

Changes in solar activity influence the colour and formation of clouds around the planet, researchers at Oxford and Reading universities found.

The icy planet is second furthest from the sun in the solar system and takes 84 Earth years to complete a full orbit – one Uranian year.

The researchers found that, once the planet's long and strange seasons are taken into account, it appears brighter and dimmer over a cycle of 11 years. This is the regular cycle of solar activity which also affects sun spots.

Karen Aplin of Oxford University's Department of Physics carried out the research with Giles Harrison, an atmospheric physicist from the Department of Meteorology at the University of Reading.

Dr. Aplin said: "The atmosphere around Uranus is one of the coldest in the solar system, but still contains clouds and ice, like our own atmosphere here on Earth.

"The changing brightness of the planet shows that something is happening to the clouds. We have found that the change is caused by two processes.

"One is chemical, caused as fluctuating levels of UV sunlight alters the colour of particles in the atmosphere. The other is due to high-speed particles from outside the solar system, known as galactic , bombarding the atmosphere and influencing the formation of ."

The scientists used data from telescopes on Earth, as well as cosmic rays measured by the Voyager 2 spacecraft, to make their assessment.

Professor Harrison said: "The sun has a magnetic field, diverting cosmic rays away from the solar system, including here on Earth. This protection is reduced when is at its lowest every 11 years, meaning more gets through.

"The atmosphere of Uranus is, like Neptune's, effectively a giant 'cloud chamber," able to respond to the incoming energetic particles. It is amazing that the effects are visible even from Earth, more than a billion miles away."

The research, published in the journal Geophysical Research Letters, follows previous research by the same authors showing a similar effect in the of Neptune, the farthest planet from the sun. The papers provide the first evidence that two planetary atmospheres have similar variations, in both cases originating from their host star.

The full paper, "Solar-Driven Variation in the Atmosphere of Uranus," can be read in the journal Geophysical Research Letters.

Explore further: There's a funny atmosphere on Neptune...

More information: K. L. Aplin et al. Solar-Driven Variation in the Atmosphere of Uranus, Geophysical Research Letters (2017). DOI: 10.1002/2017GL075374

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20 comments

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thingumbobesquire
3 / 5 (6) Dec 23, 2017
Since the sun provably causes climate changes on Uranus more than a billion miles out why would the Luddite climate change hysterics deny the same enormously magnified power of the sun here on Earth?
maholmes1
1 / 5 (1) Dec 23, 2017
Sixth-farthest known planet from the Sun. After it come Neptune, Pluto, Makemake, Haumea, and Eris.
unrealone1
1 / 5 (4) Dec 23, 2017
Climate change caused by the Sun?
3% of the worlds CO2 is man made, that's 0.0012 %
Cosmic radiation seeds clouds making CO2 is irrelevant, Priceless.
unrealone1
2.3 / 5 (6) Dec 24, 2017
https://www.youtu...25OHGglk
Tim Ball - The Deliberate Corruption of Climate Science
So much for the Hockey Stick. Great video if you have time.
carbon_unit
3.8 / 5 (4) Dec 26, 2017
Since the sun provably causes climate changes on Uranus more than a billion miles out why would the Luddite climate change hysterics deny the same enormously magnified power of the sun here on Earth?

Uh, because the CO2 greenhouse effect swamps out solar variation?
Benni
1.5 / 5 (8) Dec 26, 2017
Since the sun provably causes climate changes on Uranus more than a billion miles out why would the Luddite climate change hysterics deny the same enormously magnified power of the sun here on Earth?

Uh, because the CO2 greenhouse effect swamps out solar variation?


A trace gas making up a mere 0.04% of an atmosphere can swamp out solar variations of a planet that is 18 AU closer to the Sun than Uranus? You & Al Gore attended the same divinity school right?
TrollBane
4.3 / 5 (6) Dec 26, 2017
I invoke the Godwin's Law variant for Al Gore references. Benni, you've once again demonstrated a common informal logical fallacy instead of a substantive argument. An appeal to incredulity and supposed characteristics of someone unconnected to the issue shows you have no intellectual credibility.
Benni
1.6 / 5 (7) Dec 26, 2017
I invoke the Godwin's Law variant for Al Gore references. Benni, you've once again demonstrated a common informal logical fallacy instead of a substantive argument. An appeal to incredulity and supposed characteristics of someone unconnected to the issue shows you have no intellectual credibility.


Learn how to do Rate of Reaction Equations & you'd understand better why you have no claim to fame for intellectual credibility. If all the CO2 in Earth's atmosphere were spread into one contiguous unbroken layer just above the surface , do you know how thick that layer would be? Obviously you don't, so I'll give it to you: 1/10".

Yeah, Mr Smart Guy, tell us all about how a one tenth of an inch gas blanket creates a swamping effect on a planet by any kind of gas. But the kicker is, that CO2 does not even exist in a contiguous unbroken layer.

TrollBane
4 / 5 (8) Dec 26, 2017
No excuse for a stupid 'Al Gore' cheap shot.
carbon_unit
3.7 / 5 (3) Dec 27, 2017
Since the sun provably causes climate changes on Uranus more than a billion miles out why would the Luddite climate change hysterics deny the same enormously magnified power of the sun here on Earth?

Uh, because the CO2 greenhouse effect swamps out solar variation?


A trace gas making up a mere 0.04% of an atmosphere can swamp out solar variations of a planet that is 18 AU closer to the Sun than Uranus? You & Al Gore attended the same divinity school right?

https://www.nasa....ity.html :
"For the last 20 to 30 years, we believe greenhouse gases have been the dominant influence on recent climate change," said Robert Cahalan, climatologist at NASA's Goddard Space Flight Center in Greenbelt, Md.
Benni
1.5 / 5 (8) Dec 27, 2017
c_u, you along with Cahalan need to take some chemistry courses if you think atmospheric CO2 on planet Earth has learned a trick that the 95% atmospheric content of CO2 on Mars is incapable of learning.

According to your funny farm junk science, Mars should be going through runaway greenhouse warming, there is more TOTAL CO2 on Mars than on Earth, yet not one iota of associated WARMING. I know guys, math is tough, try some of those Rate of Reaction Equations as I suggested previously & you might actually learn what REAL SCIENCE is about & in the process gain at least a tiny bit of credibility for your inane posts.
Benni
1.6 / 5 (7) Dec 27, 2017
.....data from the Mariner 9 spacecraft showed that the surface temperature on Mars increased significantly during a dust storm


It was the friction of the dust particles with each other & along the surface that raised temperature, the resulting friction of kinetic energy of the dust particles rubbing against one another thus convectively heating anything else in the atmosphere touched by heated dust particles most of which was which was the 95% CO2 content of the atmosphere.

The terratonage of CO2 on Mars is 24.........The terratonnage of CO2 on Earth is 2.

Mars has 12 times the total quantity of CO2, so explain why there is zero greenhouse effect of CO2 there? The place should be a hellhole if CO2 had the same magical qualities as on Earth. And what with Mars often approaching within 35 million miles of us, and wow, we should see that place light up with all the trapped heat that should be trapped in all that CO2.

carbon_unit
4.2 / 5 (5) Dec 28, 2017
Mars has a very thin, dry atmosphere. Atmospheric pressure is less than 1% of Earth's. Earth also has significant water vapor (another greenhouse gas) in it's atmosphere. Also, about 25% of the Martian CO2 freezes out of the atmosphere at the pole as each hemisphere experiences winter. And I'm thinking that NASA does know a thing or two about the math of planetary atmospheres.
Benni
1.6 / 5 (7) Dec 28, 2017
Mars has a very thin, dry atmosphere. Earth also has significant water vapor (another greenhouse gas) in it's atmosphere.


So now you need to change the CO2 warming narrative once only associated with Earth. NOW you must include water vapor content on Mars because the CO2 Narrative that drives your argument on Earth doesn't work on a planet only 35 million miles further away from the Sun. Love your convoluted argument that lack of atmospheric water vapor only counts on Mars but doesn't count as a significant greenhouse gas on Earth.

25% of the Martian CO2 freezes out of the atmosphere at the pole as each hemisphere experiences winter.


So what, the fact remains the TOTAL atmosphere is 96% CO2 from top to bottom, that's a contiguous unbroken BLANKET anywhere you go on the planet, the same is not true on Earth.

And I'm thinking that NASA does know a thing or two about the math of planetary atmospheres.
.......but obviously not nearly as much as I do.
Chris_Reeve
Dec 28, 2017
This comment has been removed by a moderator.
carbon_unit
3.7 / 5 (3) Dec 28, 2017
My initial, off the cuff response to thingumbobesquire did focus on CO2 because that's what's increasing in our atmosphere - climate change. The NASA link I posted did widen things out to greenhouse gases in general. Your response confuses me. I'm asserting that Mars has almost no atmosphere and little atmospheric water vapor and Earth has a lot. That mere 35 million mile difference cuts solar irradiance from 1366 w/M2 (Earth) to 589 (Mars). Mars just doesn't have much to work with as far as heating. Back closer to this Uranus article, the NASA article attributes the variation due to solar radiation changes as about 0.1C. Thus, he sunspot cycle has minimal effect on Earth.
Benni
1.7 / 5 (6) Dec 28, 2017
I'm asserting that Mars has almost no atmosphere and little atmospheric water vapor and Earth has a lot.


OK, as I suspected from you, the magical qualities of CO2 greenhouse trapping effects can't happen except there be a tremendous quantity of water vapor available. So on Earth, the huge gaps in the non-contiguous random dispersal of CO2 shouldn't work either, because unlike Mars there is not an unbroken non-contiguous random dispersal of the molecules simply because it's about the only gas on the entire planet.

Mars just doesn't have much to work with as far as heating.


What? You mean Mars having 12 times the terratonnage of CO2 as compared to what's available on Earth isn't "much to work with" for only being 35 million miles further from the Sun than Earth? Twelve times the quantity of something to work with is a HUGE FACTOR in the random order of anything, and you think it is something to be dismissed by the wave of a hand. I see your problem.

carbon_unit
3 / 5 (2) Dec 29, 2017
Mars just doesn't have much to work with as far as heating.
What? You mean Mars having 12 times the terratonnage of CO2 as compared to what's available on Earth isn't "much to work with" for only being 35 million miles further from the Sun than Earth? Twelve times the quantity of something to work with is a HUGE FACTOR in the random order of anything, and you think it is something to be dismissed by the wave of a hand. I see your problem.

It may have 12x CO2, but that's in an atmosphere that is <1% as much as Earth's and at a distance that gets half the solar radiation. Last time I checked, 12 divided by 200 is much less than one. Also, Earth's water vapor acts as a multiplier for the CO2, so maybe we should be dividing by 400...
Benni
1.5 / 5 (8) Dec 30, 2017
It may have 12x CO2, but that's in an atmosphere that is <1% as much as Earth's


Again, so what?

Mars is TOTALLY blanketed in 96% CO2, and it's that BLANKET that is supposed to create GHG heating effects.

In the meantime, back on planet Earth, there exists only 0.04% CO2 that is randomly dispersed in huge non-blanketing gaps across the entire planet, which logically would tell an objective thinking person creates a disconnect between hypotheses & reality.

You're simply being a parrot engaged in distorting Rate of Reaction Math to make CO2 behave differently in one place versus another, you simply believe hypotheses in the face of contradictory outcomes in reality, the reason being your gross lack of education in Chemistry.

I had 3 Semesters of Chemistry during my 6 years in college majoring in Nuclear/Electrical Engineering, so I'm not impressed with parrots like you who need to fall back on other people's links to rebut logical arguments.
RealityCheck
3.4 / 5 (5) Dec 30, 2017
@Benni, @mackita, @Forum, I hope you and yours are having a safe holidays and a better New Year than the one just ending. :)

Can't stay long; very busy; so briefly:

@mackita: Yes, sometimes it does seem that (too many) people on forums just argue for the sake of their egos rather than for the sake of advancing humanity's scientific understanding of the objective reality. A pity. Let's hope the New Year and increasing pace of mainstream discovery/reviews brings all involved together in more friendly, constructive discourse, hey! :)

@Benni: You appear to have missed/forgotten my longstanding explanations using Mercury Planet's lack of 'lagging effect' atmosphere to illustrate that regardless of 'inputs', the NET EFFECT is determined by ALL atmospheric constituent/dynamics etc. Example: Even though Mercury is BAKING in the sun's radiation, its 'night side' is CRYOGENICALLY FRIGID because of lacking atmosphere/water/Co2 etc effects. Please re-thinkit, mate! :)

Cheers all.

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