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The greatest part of the Earth is protected from the Solar wind by its magnetic field. This field makes the wind particles (mainly protons and electrons) the beauty of Aurora appear. Suppose the magnetic field wasn't present. The Solar wind particles hitting the southern and northern parts of our planet would distribute themselves over whole the Earth's surface.
How would Aurora look like?
For certain it would be not slowly swirling (following the slowly changing magnetic field lines). Will we see a sparkling sky? Or what?

enter image description here

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    $\begingroup$ It would be fairly similar to Mars. If Earth had no magnetic field, the Earth's atmosphere would be thinner, and Auroras would occur wherever the solar wind hits the atmosphere. $\endgroup$
    – Star Man
    Sep 10 '20 at 20:01
  • $\begingroup$ related factoid: there is an answer or two either here in Astronomy SE or in Space Exploration SE that explains why Mars (for example) still has a magnetosphere even though the planet has no intrinsic global dipole field. It comes from currents produced as the solar wind encounters the planet, forms a shock front and then flows around the planet, at least something like that. The shape of the field is of course different than a planetary dipole, but there can be one nonetheless. $\endgroup$
    – uhoh
    Sep 11 '20 at 1:44
  • $\begingroup$ See: physics.stackexchange.com/a/335325/59023 $\endgroup$ Aug 31 at 14:54
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One way to look at this question is to consider the case of Venus, which lacks a geodynamo-created magnetic field. Despite this, there have been observations of the green emissions of excited oxygen atoms in the aftermath of solar flares, which result in higher electron density in the ionosphere. Without an intrinsic magnetosphere, the magnetic phenomena appear to be related to Venus acting directly as an obstruction to the solar wind, and would therefore not be focused on the planet's polar regions. A non-magnetic Earth might be expected to behave in a similar manner.

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I was looking through some sites and came across this - https://www.livescience.com/earth-magnetic-field.html

This clearly mentions how, if the magnetosphere surrounding the Earth weakens, the Auroras might penetrate into the Atmosphere and light up the skies closer to the equator. So, I also looked it up but, to my astonishment, I found no sources that answered this question to my satisfaction.

Though, intuition says that If there is no Magnetosphere, there should be no Aurora either.

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  • $\begingroup$ If anyone can confirm what exactly happens if there is absolutely 'no' Magnetosphere around the Earth? $\endgroup$ Sep 12 '20 at 12:20

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