Question: How wide is earth's magnetosphere?
About the article "Aurora", section "Solar wind and the magnetosphere".

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The magnetosphere of Jupiter is the largest planetary magnetosphere in the Solar System, extending up to on the dayside and almost to the orbit of Saturn on the nightside.
Jupiter's magnetosphere is stronger than Earth's by an order of magnitude, and its magnetic moment is approximately 18,000 times larger. 
Below is a list of satellites which have provided data on the Earth's magnetosphere. 
Saturn has an intrinsic magnetic field that has a simple, symmetric shape – a magnetic dipole.
Its strength at the equator – 0.2 gauss (20 µT) – is approximately one twentieth of that of the field around Jupiter and slightly weaker than Earth's magnetic field.
As a result Saturn's magnetosphere is much smaller than Jupiter's.
When "Voyager 2" entered the magnetosphere, the solar wind pressure was high and the magnetosphere extended only 19 Saturn radii, or 1.1 million km (712,000 mi), although it enlarged within several hours, and remained so for about three days.
Most probably, the magnetic field is generated similarly to that of Jupiter – by currents in the liquid metallic-hydrogen layer called a metallic-hydrogen dynamo.
This magnetosphere is efficient at deflecting the solar wind particles from the Sun.
The moon Titan orbits within the outer part of Saturn's magnetosphere and contributes plasma from the ionized particles in Titan's outer atmosphere.
Saturn's magnetosphere, like Earth's, produces aurorae. 
The Earth's magnetic field varies over a wide range of timescales.
The longer-term variations, typically occurring over decades to millennia, are predominantly the result of dynamo action in the Earth's core.
Geomagnetic variations on timescales of seconds to years also occur, due to dynamic processes in the ionosphere, magnetosphere and heliosphere.
These changes are ultimately tied to variations associated with the solar activity (or sunspot) cycle and are manifestations of space weather.
The fact that the geomagnetic field does respond to solar conditions can be useful, for example in investigating Earth structure using magnetotellurics, but it also creates a hazard.
This geomagnetic hazard is primarily a risk to technology under the Earth's protective atmospheric blanket. 
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.