Question: Which direction does Earth's magnetic field point during magnetopause?
About the article "Aurora", section "Frequency of occurrence".

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Over Earth's equator, the magnetic field lines become almost horizontal, then return to connect back again at high latitudes.
However, at high altitudes, the magnetic field is significantly distorted by the solar wind and its solar magnetic field.
On the dayside of Earth, the magnetic field is significantly compressed by the solar wind to a distance of approximately .
Earth's bow shock is about thick and located about from Earth.
The magnetopause exists at a distance of several hundred kilometers off earth's surface.
Earth's magnetopause has been compared to a sieve because it allows solar wind particles to enter.
Kelvin–Helmholtz instabilities occur when large swirls of plasma travel along the edge of the magnetosphere at a different velocity from the magnetosphere, causing the plasma to slip past.
This results in magnetic reconnection, and as the magnetic field lines break and reconnect, solar wind particles are able to enter the magnetosphere.
On Earth's nightside, the magnetic field extends in the magnetotail, which lengthwise exceeds .
Earth's magnetotail is the primary source of the polar aurora.
Also, NASA scientists have suggested or "speculated" that Earth's magnetotail can cause "dust storms" on the Moon by creating a potential difference between the day side and the night side. 
The ions and electrons of a plasma interacting with the Earth's magnetic field generally follow its magnetic field lines.
These represent the force that a north magnetic pole would experience at any given point.
(Denser lines indicate a stronger force.)
Plasmas exhibit more complex second-order behaviors, studied as part of magnetohydrodynamics.
Thus in the "closed" model of the magnetosphere, the magnetopause boundary between the magnetosphere and the solar wind is outlined by field lines.
Not much plasma can cross such a stiff boundary.
Its only "weak points" are the two polar cusps, the points where field lines closing at noon (-z axis GSM) get separated from those closing at midnight (+z axis GSM); at such points the field intensity on the boundary is zero, posing no barrier to the entry of plasma.
(This simple definition assumes a noon-midnight plane of symmetry, but closed fields lacking such symmetry also must have cusps, by the fixed point theorem.)
The amount of solar wind energy and plasma entering the actual magnetosphere depends on how far it departs from such a "closed" configuration, i.e.
the extent to which Interplanetary Magnetic Field field lines manage to cross the boundary.
As discussed further below, that extent depends very much on the direction of the Interplanetary Magnetic Field, in particular on its southward or northward slant.
Trapping of plasma, e.g.
of the ring current, also follows the structure of field lines.
A particle interacting with this B field experiences a Lorentz Force which is responsible for many of the particle motion in the magnetosphere.
Furthermore, Birkeland currents and heat flow are also channeled by such lines — easy along them, blocked in perpendicular directions.
Indeed, field lines in the magnetosphere have been likened to the grain in a log of wood, which defines an "easy" direction along which it easily gives way. 
The magnetopause is the abrupt boundary between a magnetosphere and the surrounding plasma.
For planetary science, the magnetopause is the boundary between the planet’s magnetic field and the solar wind.
The location of the magnetopause is determined by the balance between the pressure of the dynamic planetary magnetic field and the dynamic pressure of the solar wind.
As the solar wind pressure increases and decreases, the magnetopause moves inward and outward in response.
Waves (ripples and flapping motion) along the magnetopause move in the direction of the solar wind flow in response to small scale variations in the solar wind pressure and to Kelvin-Helmholtz instability.
The solar wind is supersonic and passes through a bow shock where the direction of flow is changed so that most of the solar wind plasma is deflected to either side of the magnetopause, much like water is deflected before the bow of a ship.
The zone of shocked solar wind plasma is the magnetosheath.
At Earth and all the other planets with intrinsic magnetic fields, some solar wind plasma succeeds in entering and becoming trapped within the magnetosphere.
At Earth, the solar wind plasma which enters the magnetosphere forms the plasma sheet.
The amount of solar wind plasma and energy which enters the magnetosphere is regulated by the orientation of the interplanetary magnetic field which is embedded in the solar wind.
The Sun and other stars with magnetic fields and stellar winds have a solar magnetopause or heliopause where the stellar environment is bounded by the interstellar environment. 
Saturn's internal magnetic field deflects the solar wind, a stream of ionized particles emitted by the Sun, away from its surface, preventing it from interacting directly with its atmosphere and instead creating its own region, called a magnetosphere, composed of a plasma very different from that of the solar wind.
The magnetosphere of Saturn is the second–largest magnetosphere in the Solar System after that of Jupiter.
As with Earth's magnetosphere, the boundary separating the solar wind's plasma from that within Saturn's magnetosphere is called the magnetopause.
The magnetopause distance from the planet's center at the subsolar point varies widely from 16 to 27 Rs (Rs=60,330 km is the equatorial radius of Saturn).
The magnetopause's position depends on the pressure exerted by the solar wind, which in turn depends on solar activity.
The average magetopause standoff distance is about 22 Rs.
In front of the magnetopause (at the distance of about 27 Rs from the planet) lies the bow shock, a wake-like disturbance in the solar wind caused by its collision with the magnetosphere.
The region between the bow shock and magnetopause is called the magnetosheath.
At the opposite side of the planet, the solar wind stretches Saturn's magnetic field lines into a long, trailing magnetotail, which consists of two lobes, with the magnetic field in the northern lobe pointing away from Saturn and the southern pointing towards it.
The lobes are separated by a thin layer of plasma called the tail current sheet.
Like Earth’s, Saturn's tail is a channel through which solar plasma enters the inner regions of the magnetosphere.
Similar to Jupiter, the tail is the conduit through which the plasma of the internal magnitospheric origin leaves the magnetosphere.
The plasma moving from the tail to the inner magnitopshere is heated and forms a number of radiation belts. 
Jupiter's internal magnetic field prevents the solar wind, a stream of ionized particles emitted by the Sun, from interacting directly with its atmosphere, and instead diverts it away from the planet, effectively creating a cavity in the solar wind flow, called a magnetosphere, composed of a plasma different from that of the solar wind.
The Jovian (i.e.
pertaining to Jupiter) magnetosphere is so large that the Sun and its visible corona would fit inside it with room to spare.
If one could see it from Earth, it would appear five times larger than the full moon in the sky despite being nearly 1700 times farther away.
As with Earth's magnetosphere, the boundary separating the denser and colder solar wind's plasma from the hotter and less dense one within Jupiter's magnetosphere is called the magnetopause.
The distance from the magnetopause to the center of the planet is from 45 to 100 "R"j (where "R"j=71,492 km is the radius of Jupiter) at the subsolar point—the unfixed point on the surface at which the Sun would appear directly overhead to an observer.
The position of the magnetopause depends on the pressure exerted by the solar wind, which in turn depends on solar activity.
In front of the magnetopause (at a distance from 80 to 130 "R"j from the planet's center) lies the bow shock, a wake-like disturbance in the solar wind caused by its collision with the magnetosphere.
The region between the bow shock and magnetopause is called the magnetosheath.
At the opposite side of the planet, the solar wind stretches Jupiter's magnetic field lines into a long, trailing magnetotail, which sometimes extends well beyond the orbit of Saturn.
The structure of Jupiter's magnetotail is similar to Earth's.
It consists of two lobes (blue areas in the figure), with the magnetic field in the southern lobe pointing toward Jupiter, and that in the northern lobe pointing away from it.
The lobes are separated by a thin layer of plasma called the tail current sheet (orange layer in the middle).
Like Earth's, the Jovian tail is a channel through which solar plasma enters the inner regions of the magnetosphere, where it is heated and forms the radiation belts at distances closer than 10 "R"j from Jupiter.
The shape of Jupiter's magnetosphere described above is sustained by the neutral sheet current (also known as the magnetotail current), which flows with Jupiter's rotation through the tail plasma sheet, the tail currents, which flow against Jupiter's rotation at the outer boundary of the magnetotail, and the magnetopause currents (or Chapman-Ferraro currents), which flow against rotation along the dayside magnetopause.
These currents create the magnetic field that cancels the internal field outside the magnetosphere.
They also interact substantially with the solar wind.
Jupiter's magnetosphere is traditionally divided into three parts: the inner, middle and outer magnetosphere.
The inner magnetosphere is located at distances closer than 10 "R"j from the planet.
The magnetic field within it remains approximately dipole, because contributions from the currents flowing in the magnetospheric equatorial plasma sheet are small.
In the middle (between 10 and 40 "R"j) and outer (further than 40 "R"j) magnetospheres, the magnetic field is not a dipole, and is seriously disturbed by its interaction with the plasma sheet (see magnetodisk below).