In my SciFi-Magic RPG campaign, the main characters are on Mars, which has been converted to a prison planet.

A large device, drilled into the north and south poles, reaching into the core, heating and stirring up the core in order to create a magnetosphere which can sustain an atmosphere. The atmosphere is created through a portal to the Elemental Plane of Air.

Recently, large aliens from another system landed on Mars unopposed by the rest of the Solar System (as the Solar System is fighting off those aliens on Earth, Venus, and Mercury), and the aliens were able to destroy the devices on the poles and began re-freezing the core.

My questions are two onefold. Just one fold. A single fold now.

1. Does my method of creating a magnetosphere make sense?

  1. What would the sky look like if that device was destroyed and the core was frozen again?

I imagine it would look like the sky started to either fade or have dark patches as the atmosphere was depleted by solar winds, but I'm happy to be corrected, since I'd like as much accuracy as possible!

Thanks, Fynn

  • $\begingroup$ Welcome to world building. We have a 1 question per post policy. More info in the help center $\endgroup$
    – L.Dutch
    Commented May 8, 2021 at 11:07
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    $\begingroup$ The depletion of the atmosphere due to solar wind etc. is a geological process. It takes many millions of years. There is no need to create a magnetic field, and nothing will happen if an existing magnetic field is turned off; nobody cares what will happen a million years from now. $\endgroup$
    – AlexP
    Commented May 8, 2021 at 14:43
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    $\begingroup$ Fixed! OK Dutch - RELEASE THE HOUNDS! $\endgroup$
    – Willk
    Commented May 8, 2021 at 16:28
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    $\begingroup$ @Fynn The solar wind removes atmosphere very slowly. Planets also lose atmosphere when molecues and atoms in the upper atmoshere have velocities higher than the escape vlocity of the planet. The escape velocity of Mars is 5.027 kilometers per second, 0.449 of the 11.186 kilometers per second of Earth. So how many seconds or miliions of years would it take an Earth-like atmosphere to escpe from Mars? A few thousand years according to page 35 of: rand.org/content/dam/rand/pubs/commercial_books/2007/… $\endgroup$ Commented May 8, 2021 at 18:44
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    $\begingroup$ @Willk hounds released, mate. $\endgroup$ Commented May 8, 2021 at 19:28

1 Answer 1


Worldwide aurora.

The aurora on Earth is produced by interactions between the solar wind and Earths magnetic field, which diverts a lot of the charged particles of the wind and concentrates the rest at the poles. It is the interaction between charged particles and atmospheric gas molecules that produces the light.

Without earths magnetic field, the solar wind would rain down on all of the earth equally.


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.

More particles would hit the atmosphere and they would not be concentrated at the poles. The nighttime sky across the planet would be more uniformly bright. Colors would depend on the constitutents of the Martian atmosphere, with each gas conferring its own color. The glow would not shift and flicker with magnetic field lines as the aurora does. Apparent movement would be due to differences in the strength of the solar wind.

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    $\begingroup$ +1 for the details in that last paragraph about colors and flickering. $\endgroup$
    – Tom
    Commented May 21, 2021 at 0:33

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