<p>The galactic field strength is about 6 μGauss near the Sun. The Sun's magnetic field strength is 35 μGauss near the Earth but this varies a bit with the solar cycle. Earth's magnetic field is 0.2 - 0.6 Gauss. Therefore, the Earth's magnetic field is insignificantly perturbed by the galactic magnetic field.</p>
<p>The solar wind blows a bubble around the solar system called the heliosphere that keeps out the intergalactic medium along with its magnetic field.  It ends at the heliopause (beyond Neptune).  Exactly, where the heliopause is should be dependent on the strength of the intergalactic magnetic field, but also on the ISM density.</p>
<p><a href="https://i.sstatic.net/yzwcvu0w.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/yzwcvu0w.png" alt="
This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto.
Credits: NASA/JPL-Caltech" /></a></p>
<p><em>This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto.
Credits: NASA/JPL-Caltech</em></p>
<p>The position of the heliosphere has an influence on the amount of galactic cosmic radiation enters into the solar system and thus has an influence on the health and safety of astronauts venturing beyond the Earth's magnetopause.</p>
<p>The magnetic fields are stronger in the spiral arms, typically 10 - 15 μGauss.  But, still insignificant except in the outer solar system.   The Sun passes through spiral arms on a timescale of order 100 millions years.</p>

CC BY-SA 4.0
2024-07-05T20:17:57.363Z
2024-07-05T20:56:31.317Z
2024-07-05T20:56:31.317Z
eshaya
<p>Absolutely nothing happen to planet Earth.</p>
<p>The majority of interstellar medium exist as <a href="https://en.wikipedia.org/wiki/Interstellar_medium" rel="nofollow noreferrer">hot ionized medium</a>, the number density is <span class="math-container">$10^4 - 10^6 /m^3$</span>, the average number density of Earth's atmosphere is around <span class="math-container">$10^{27} /m^3$</span>. So it is very spread out. The closest star is <span class="math-container">$4.2ly$</span> away from us, the number density of stars is <span class="math-container">$1 /69pc^3$</span>. So there is literally nothing than Earth can run into while crossing the galactic plane thus literally nothing can change the magnetic field of the solar system.</p>
<p>Yes, magnetic field does not need medium to spread out, but it is very hard to come across a object with a strong enough magnetic field to alter the magnetic field of planet Earth, and the galactic magnetic field can simply be ignored because it is just too small to even care about it (we are experiencing it every single day but nothing happened).</p>

CC BY-SA 4.0
2024-07-03T01:47:55.330Z
I asked about magnetism.   You seem to be trying to, exasperatingly, answer a different question.
Jim
CC BY-SA 4.0
2024-07-04T03:02:18.363Z
@Jim, I apologize for yesterday, I edited the answer and now it is about magnetism.
Polaris5744
CC BY-SA 4.0
2024-07-02T23:19:19.243Z
2024-07-04T03:08:24.163Z
2024-07-04T03:08:24.163Z
Polaris5744
<p>Does anything happen to our Solar System after we transit the Galactic plane?   Is there one polarity &quot;above&quot; (artificially relatively speaking) the plane, and the opposite polarity &quot;below&quot;?    When our entire Solar System transits the plane, what effects do the magnetism (or the change in polarity thereof) have on Earth's magnetosphere?</p>

CC BY-SA 4.0
2024-07-03T07:10:31.270Z
How do you define the plane? What indications do you have that anything changes when "the solar system transits the plane"? Are there any such indications e.g. from analogues like when the Moon crosses the ecliptic on its monthly orbit twice or any hints like in paleo-stratigraphic records? What's the ratio of magnetic fields you expect? Does https://astronomy.stackexchange.com/questions/42053/what-pulls-the-sun-above-the-galactic-plane-and-pulls-it-below-the-galactic-plan answer your question?
planetmaker
CC BY-SA 4.0
2024-07-03T17:49:59.607Z
I can't see what problems people have with this question. It's asking about the relative strength and morphology of the Galactic magnetic field compared with that of the Earth.
ProfRob
CC BY-SA 4.0
2024-07-03T21:59:10.917Z
Thanks for your responses.  The earlier ones (since deleted) were pretty annoying.   I am indeed asking about the strength and morphology, but I don't have this vocabulary natively.   Earth has a N/S polarity, and a currently moving pole at that.  I'm wondering about how the strength and polarity (morphology?) of the galactic field affects our own planet's polarity as we transit the galactic plane, particularly as we  near, reach or pass the point where the galactic field bends back to the other pole.   Forgive me my rudimentary language.
Jim
CC BY-SA 4.0
2024-07-03T22:18:26.310Z
@eshaya does the measurement of the galactic field strength ever fluctuate?  I mean over time, was it ever lower or significantly higher than 6 μGauss near the Sun?   And do we know what that strength is near Earth?  (I'm not sure why it would be any different, but just wondering)
Jim
CC BY-SA 4.0
2024-07-06T06:24:57.473Z
Comments are not for answers.
ProfRob
<magnetic-field><galactic-dynamics>
What is the nature of magnetism within and without the Galatic plane?
Jim
# What is the nature of magnetism within and without the Galatic plane?

(Asked by: username_0 on 2024-07-02)

Does anything happen to our Solar System after we transit the Galactic plane? Is there one polarity "above" (artificially relatively speaking) the plane, and the opposite polarity "below"? When our entire Solar System transits the plane, what effects do the magnetism (or the change in polarity thereof) have on Earth's magnetosphere?

**Tags:** magnetic-field, galactic-dynamics

> **Comments:**
> **username_1**: How do you define the plane? What indications do you have that anything changes when "the solar system transits the plane"? Are there any such indications e.g. from analogues like when the Moon crosses the ecliptic on its monthly orbit twice or any hints like in paleo-stratigraphic records? What's the ratio of magnetic fields you expect? Does https://astronomy.stackexchange.com/questions/42053/what-pulls-the-sun-above-the-galactic-plane-and-pulls-it-below-the-galactic-plan answer your question?  
> **username_2**: I can't see what problems people have with this question. It's asking about the relative strength and morphology of the Galactic magnetic field compared with that of the Earth.  
> **username_0**: Thanks for your responses.  The earlier ones (since deleted) were pretty annoying.   I am indeed asking about the strength and morphology, but I don't have this vocabulary natively.   Earth has a N/S polarity, and a currently moving pole at that.  I'm wondering about how the strength and polarity (morphology?) of the galactic field affects our own planet's polarity as we transit the galactic plane, particularly as we  near, reach or pass the point where the galactic field bends back to the other pole.   Forgive me my rudimentary language.  
> **username_0**: @username_3 does the measurement of the galactic field strength ever fluctuate?  I mean over time, was it ever lower or significantly higher than 6 μGauss near the Sun?   And do we know what that strength is near Earth?  (I'm not sure why it would be any different, but just wondering)  
> **username_2**: Comments are not for answers.  

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## 2 answers

### Answer by username_3 on 2024-07-05. Score: 2

The galactic field strength is about 6 μGauss near the Sun. The Sun's magnetic field strength is 35 μGauss near the Earth but this varies a bit with the solar cycle. Earth's magnetic field is 0.2 - 0.6 Gauss. Therefore, the Earth's magnetic field is insignificantly perturbed by the galactic magnetic field.

The solar wind blows a bubble around the solar system called the heliosphere that keeps out the intergalactic medium along with its magnetic field. It ends at the heliopause (beyond Neptune). Exactly, where the heliopause is should be dependent on the strength of the intergalactic magnetic field, but also on the ISM density.

[![
This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto.
Credits: NASA/JPL-Caltech](https://i.sstatic.net/yzwcvu0w.png)](https://i.sstatic.net/yzwcvu0w.png)

*This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto.
Credits: NASA/JPL-Caltech*

The position of the heliosphere has an influence on the amount of galactic cosmic radiation enters into the solar system and thus has an influence on the health and safety of astronauts venturing beyond the Earth's magnetopause.

The magnetic fields are stronger in the spiral arms, typically 10 - 15 μGauss. But, still insignificant except in the outer solar system. The Sun passes through spiral arms on a timescale of order 100 millions years.


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### Answer by username_4 on 2024-07-02. Score: 0

Absolutely nothing happen to planet Earth.

The majority of interstellar medium exist as [hot ionized medium](https://en.wikipedia.org/wiki/Interstellar_medium), the number density is $10^4 - 10^6 /m^3$, the average number density of Earth's atmosphere is around $10^{27} /m^3$. So it is very spread out. The closest star is $4.2ly$ away from us, the number density of stars is $1 /69pc^3$. So there is literally nothing than Earth can run into while crossing the galactic plane thus literally nothing can change the magnetic field of the solar system.

Yes, magnetic field does not need medium to spread out, but it is very hard to come across a object with a strong enough magnetic field to alter the magnetic field of planet Earth, and the galactic magnetic field can simply be ignored because it is just too small to even care about it (we are experiencing it every single day but nothing happened).

> **Comments:**
> **username_0**: I asked about magnetism.   You seem to be trying to, exasperatingly, answer a different question.  
> **username_4**: @username_0, I apologize for yesterday, I edited the answer and now it is about magnetism.  

---

