Jupiter's magnetosphere extends "seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction" and Saturn's magnetosphere extends towards the Sun on average 22 Rs (Rs=60,330 km is the equatorial radius of Saturn). My question is: do these magnetospheres actually touch each other when the planets are on the same line?


2 Answers 2


A planet's magnetic field extends furthest in the direction away from the sun. This longest part of the magnetic field is called the magnetotail.

Jupiter's magnetic field is huge. It's tail extends up to 7,000 Jupiter radii, or about 490 million km per Wikipedia.

As closest pass, Jupiter's aphelion is about 816 million km from the sun and Saturn's perihelion, is about 1,352 million km from the sun, so they get as close as 546 million km. The distance Saturn's magnetosphere reaches forward would be a handful of Jupiter radii, but what the math suggests is that mostly Jupiter's tail doesn't reach that far, but it does reach most of the way to Saturn. There's some room for error based on how accurate the 7,000 Jupiter radii figure is. At the very least it nearly reaches Saturn. The fields might occasionally touch and exchange particles but probably rarely and not a lot of particles, given that it's the tail end of Jupiter's magnetic field.

As a sidebar, the Moon passes through the Earth's magnetotail.


The simple answer is yes, because magnetic fields extend to infinity.

Your question should ask if a significant interaction is present. My question would be, what is a significant interaction?

  • $\begingroup$ my question was about magnetospheres, I corrected the title to better reflect this intent $\endgroup$
    – symbiotech
    Commented Apr 27, 2014 at 2:58
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    $\begingroup$ @symbiotech The magnetospheres are created by the magnetic fields from the planets. Like I said, how weak does the magnetosphere need to be before you consider it is too weak for an interaction? $\endgroup$
    – LDC3
    Commented Apr 27, 2014 at 3:14
  • $\begingroup$ While it's generally true that a magnetic field extends forever, it's not accurate to say that a magnetosphere extends forever. They extend far, but there is a point past Jupiter when its no longer a Jupiter field and the sun field takes over. The long extension of the magnetosphere is called the magnetotail. Earth's extends some 600,000 km. history.nasa.gov/EP-177/ch3-4.html $\endgroup$
    – userLTK
    Commented Apr 28, 2017 at 9:55
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    $\begingroup$ @userLTK I think the OP's question could be reasonably interpreted as asking if at any point during their orbits do we have a transition from Jupiter's magnetosphere to Saturn's that does not first pass through the Sun's. $\endgroup$ Commented Apr 29, 2017 at 0:49

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