Sun's Magnetic Field

[Little Bang]

Could we detect the sun's magnetic field from a spaceship located in Earth's orbit and there was no Earth or any other planets in the solar system?

[Turtle]

yes

 

Stellar magnetic field

...

Measurement

 

The magnetic field of a star can be measured by means of the Zeeman effect. Normally the atoms in a star's atmosphere will absorb certain frequencies of energy in the electromagnetic spectrum, producing characteristic dark absorption lines in the spectrum. When the atoms are within a magnetic field, however, these lines become split into multiple, closely spaced lines. The energy also becomes polarized with an orientation that depends on orientation of the magnetic field. Thus the strength and direction of the star's magnetic field can be determined by examination of the Zeeman effect lines.[2][3]

 

A stellar spectropolarimeter is used to measure the magnetic field of a star. This instrument consists of a spectrograph combined with a polarimeter. ...

 

Edited June 4, 2012 by Turtle

[CraigD]

Could we detect the sun's magnetic field from a spaceship located in Earth's orbit and there was no Earth or any other planets in the solar system?

Yes.

 

From 1992 to 2009, my favorite solar observation spacecraft, Ulysses, orbited the Sun in a very eccentric (1-5 AU) out-of-the-ecliptic (80.2^o) orbit. Though not an Earth-like orbit (a nearly circular 1 AU in-the-ecliptic orbit), it’s essentially all alone in its orbit (it’s still there, just not observing and sending data anymore, as it’s thermal nuke generator ran down beyond usability in ’09). Before Ulysses, we had only guesses about what the Suns poles really looked like. It found wonderful surprises.

 

My new favorite solar spacecraft (assuming nothing dire cancels its planned 2018 launch) will be Solar Probe+. It’ll make multiple close passes (about 8.5 solar radii, 0.03 AU) of the Sun, and I expect, add as much or more new knowledge about the Sun than Ulysses did.

 

There’s a good page on solar observatory spacecraft at this Scholarpedia article.