How Uranus reacts to the solar cycle

Posted: December 22, 2017 by oldbrew in Clouds, cosmic rays, Cycles, research, solar system dynamics
Tags: ,

Uranus [image credit: NASA]


One of the two processes involved is “due to high-speed particles from outside the solar system, known as galactic cosmic rays, bombarding the atmosphere and influencing the formation of clouds”, reports Phys.org. If so, it looks like further evidence for the Svensmark hypothesis.

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 cosmic rays, bombarding the atmosphere and influencing the formation of clouds.”

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 solar activity is at its lowest every 11 years, meaning more cosmic radiation 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 atmosphere 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.

Source: How the sun’s influence on the remote planet Uranus changes its brightness in the sky | Phys.org

Comments
  1. craigm350 says:

    Reblogged this on WeatherAction News and commented:
    Changes in solar activity influence the colour and formation of clouds around the planet,
    But TSI is flat!! 😂

    [reply] UV not so much 🙂

  2. oldbrew says:

    Quote: This is the first evidence of two planetary atmospheres—Neptune originally and now Uranus—showing similar variations, in both cases originating from their host star

    Plain Language Summary

    Measurements of the planets Uranus and Neptune have been made using a telescope, for every year from 1972 to 2015. How bright a planet appears to us is an indicator of the cloud cover in its atmosphere. An 11 year brightness variation was spotted in the Neptune observations many years ago, indicating that a process linked to the Sun’s 11 year activity cycle affects the planet’s clouds. This inspired us to look at the data for Uranus more closely, and we found the same signal as for Neptune. There are two possible explanations. One possibility is chemical, when light from the Sun affects the color of particles in the planet’s atmosphere. Our other possibility is that energetic particles from outside the solar system, cosmic rays, influence particle, or cloud formation. (Cosmic rays are “bent” away from the solar system by the Sun acting as a magnet, so are also affected by its 11 year activity cycle). In our results, we actually find that both of them have a small effect on the clouds on Uranus. This is the first evidence of two planetary atmospheres—Neptune originally and now Uranus—showing similar variations, in both cases originating from their host star.

    Solar-Driven Variation in the Atmosphere of Uranus
    Authors
    K. L. Aplin,
    R. G. Harrison
    First published: 18 December 2017

    http://onlinelibrary.wiley.com/doi/10.1002/2017GL075374/abstract;jsessionid=4FBBA77463E3C3649B6EA858802FC102.f02t01

  3. Bitter&twisted says:

    And amazingly, despite the Earth being considerably closer to the Sun than Youranus it has no effect on the clouds, or the climate, which is dominated by back radiation from CO2.

  4. Could that 11-year cycle be related to the orbital period of Jupiter?

    It would be interesting to see where Jupiter is located during the Neptune cycle.

  5. oldbrew says:

    Dale – yes it could be, with other planetary influences preventing a 1:1 match.

    14 Jupiter-Neptune conjunctions = the solar motion period of ~179 years, which is discussed in a new paper here:
    https://tallbloke.wordpress.com/2017/12/23/sidorenkov-and-wilson-new-solar-retrograde-motion-paper/

  6. oldbrew says:

    Baby It’s Cold Outside – evidence of solar cycle affecting Earth’s cloud cover
    Anthony Watts December 31, 2017
    Guest essay by David Archibald

    News comes that the light reflected back from Uranus is affected by the solar cycle.

    If the solar cycle affects the climate of Uranus then it could reasonably be expected to affect Earth’s climate. The solar irradiance hitting Uranus is 3.69 W/m2, what hits Earth is 368 times greater.

    Read more: http://wattsupwiththat.com/2017/12/31/baby-its-cold-outside-evidence-of-solar-cycle-affecting-earths-cloud-cover/

    Solar cycle modulation of cosmic rays as first proposed by Svalgaard and Wilcox in 1976
    http://www.leif.org/research/HCS-Nature-1976.pdf

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