New addon (work in progress) : magnetic field of the planets

[Cham]

I just finished a new "layer" for Celestia (with toggle script to switch the layer ON/OFF at will) : the magnetic field of the planets (actually Earth and the giants). I'll publish the addon only when Celestia 1.6.0 is officially out and if people show enough interest in it. Here are some previews :

earth.jpg

jupiter.jpg

saturn.jpg

[Cham]

... and here are the strange cases of Uranus and Neptune (notice the field offset !) :

uranus.jpg

neptune.jpg

In the case of Jupiter, I may add Io's flux tube and the plasma torus made from the dust ejected by Io's volcanism.

The addon also includes the typical trajectory of charged particles trapped into the field, that can be toggle ON/OFF independently. This is usefull to show the Van Allen belt around the Earth, for example.

[Fenerit]

I'm VERY interest in it!

[ajtribick]

Aren't the planetary magnetic fields also affected by the solar wind, which means they are compressed in the sunward direction and extended in the antisunward direction? These screenshots don't seem to reflect that.

[Cham]

The fields shown are the dipolar component. In the case of Jupiter and Earth for example, it account of about 90% of their field.

I also want to build a complete field (with shock wave). However, I don't have any precise data about that, and the complete field is evolving in time while the planet moves around Sol (the magnetic axis is tilted). There's no way I can show this evolution in Celestia yet.

Anyway, the dipolar field is a very good approximation at close range (but not too close, since the local anomalies may be important). In the case of Jupiter, the approximation is good up to about 20 Jupiter radii.

In the case of Earth, there are good information here:

# http://gsc.nrcan.gc.ca/geomag/nmp/northpole_f.php
# http://www-ssc.igpp.ucla.edu/personnel/ ... earth_mag/
# http://www.ngdc.noaa.gov/geomag/faqgeom.shtml
# http://swdcwww.kugi.kyoto-u.ac.jp/poles/polesexp.html

[Fenerit]

Aren't the planetary magnetic fields also affected by the solar wind, which means they are compressed in the sunward direction and extended in the antisunward direction? These screenshots don't seem to reflect that.

[Cham]

Mad gravity experiment :

I made an interesting experiment with charged particles in Jupiter's magnetic field. Here's a Sulfur ion dropped with an initial velocity of 80% c (yeah, it's exagerated). The Magnetic field is using real parameters for Jupiter (in the dipolar approximation). Full special relativity, radiation (negligible in this case), etc. However, I wanted to see some gravitational effects (usualy negligible in this situation, on a short period of time), so I raised Jupiter's mass by a factor of 500 million ! Here what it gives :

In Mathematica :

super-Jupiter.jpg

In Celestia :

jup2.jpg

jup1.jpg

The strong (MUCH exagerated) gravity is draging the particle until it smashes Jupiter !

[Fightspit]

It is very strange and weird, even a fly can't do the same path

[Cham]

Here's a first step attempt at creating a more realistic field for the Earth :

field.jpg

I simply aded a quadrupole term to the dipolar magnetic field. Of course, there will be a problem in Celestia since the field should be oriented toward the Sun (with a rotation period of 365 days), while Earth is rotating with a 24hr period and the magnetic axis is tilted relative to it.

I'll have to add a field deformation term to change the shape on the elongated side... Not sure this is really worth it.

[BobHegwood]

Paf?

I like it... Hee, hee...