Uranus’s magnetic field switches on and off daily


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Using data from the Voyager 2 flyby of Uranus in 1986, scientists now think that the gas giant’s magnetic field switches on and off each day as the planet rotates.

Uranus’s magnetosphere, in contrast [to Earth], exhibits precise regularity in its mode changes. This, say the researchers, is because it lies at an angle of roughly 60 degrees to the planet’s spin axis, causing its interaction with incoming solar winds to vary dramatically during the 17 hours it takes for a full rotation. “Uranus is a geometric nightmare,” says Paty.

“The magnetic field tumbles very fast, like a child cartwheeling down a hill head over heels. When the magnetised solar wind meets this tumbling field in the right way, it can reconnect and Uranus’s magnetosphere goes from open to closed to open on a daily basis.”

The researchers suggest the robust and regular changes to the magnetosphere may mean that the icy planet has spectacular auroras across its breadth every day.

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4 comments

  • LocalFluff

    It is easy to think that Uranus and Neptune are boring ice giants. That is only an illusion because so little is known about them.

    And it should be named Celestus, or some Latin format of that. Why is there a Greek among the Romans? Or rename Mars “Pyroeis”, fine for me. But astronomers need to get a grip on their nomenclature. The astrologers were at least consistent.

  • Diane Wilson

    Uranus and Neptune cannot possibly be more boring than Pluto.

  • Max

    From the article;
    ” In a paper published in the Journal of Geophysical Research: Space Physics, the scientists report that the magnetosphere flips between “open” and “closed” modes once every rotation of the planet.”

    From what I know of magnets, they do not turn on and off. Unless the magnetic field is caused by another phenomenon like an electric arc or current in the atmosphere similar to what they discovered on Jupiter.
    Uranus magnetic field is at 60° as compared to the earth which magnetic north is 10° from true north. Earths magnetic field varies from .25 Gauss to .65 Gauss.
    Uranus has a large variation from .1 Gauss in the south pole to 1.1 Gauss at the north making the magnetic field flux from intense to weak… Appearing to be “on” then “off”, “open” then “closed” with every 17 hour rotation.
    As for letting “in” the “solar wind”, uranus is 20 times as far from the sun as we are. And with all that empty space to fill, the solar wind must be 20 times less powerful. Just as Jupiter creates its own Aurora, something similar maybe occurring here. All magnetic fields will attract charged particles in the solar wind, concentrating the Aurora in the polar region where it is following the lines of magnetic force.
    The same is true of cosmic radiation which is much more powerful and comes from outside the solar system.
    The point is, Aurora is always strongest where the magnetic field is strongest, not weakest.

    Another odd feature that I did not know about. The winds at the equator flow in the opposite direction of rotation at 230 mph. At 20°, the wind speed is zero, and this is where The temperatures are the coldest of any planet in the solar system of a -364°F. (this reminds me of Richard Hoagland’s 19.5° theory from the art bell days) The winds pick up in the other direction to 500 mph between 45 and 60° Latitude.
    The temperature has a wild range also… From 1000° F in the thermosphere, 200 km above the clouds, to the troposphere with the -364°F, to deep under the atmosphere where there are 8 million bars of pressure to generate 8,540°F. (A conundrum for the laws of thermodynamics) That’s just 1000° cooler than the photosphere of the sun. Perhaps a thermal pile reaction of the heat variation in a conductive hydrogen atmosphere… just like the piece of copper in your pilot light in your furnace. Ground is insulated by a thick layer of diamonds? Where is the power to flow to but the path of least resistance…
    Even though it is four times the radius making 16 times the surface area of the earth… It has .88 of earths gravity. It’s just a big ball of fluff.
    (Wikipedia says that they do not know why the thermosphere is so hot this deep into space, they blame it on UV radiation and IR radiation)(The moon in earths orbit is 250°, 1/4 the temperature of Uranus thermosphere 20 times closer to the sun)
    And they call it an “ice giant”…

  • LocalFluff

    I surprised they know so much about the temperatures of Uranus. The sunlight and Solar wind should even be 400 times as weak at Uranus. Gravity waves are said to weaken linearly by distance, don’t ask me how that works.

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