As per the end of the last post, we will start this story in 1963.
A Rocket in the Aurora
|Magnetic field measuremens of |
the US Navy rocket 1963-38C
showing the strong transverse
What is the source?
|A simple model of the Earth's|
magnetosphere, with the solar wind
(orange) interacting with the Earth's
At the front of the Earth the magnetic field is compressed by the solar wind. At the back of the Earth, however, the magnetic field gets pulled along with the solar wind and is stretched into a long tail. This stretched magnetic field, like a stretched rubber band, can store a lot of energy that can be released after a certain trigger is pulled.
|The simplest version of magnetic |
reconnection, field lines are pushed
together in the middle, and at the
central part (the X-point) new
connections are made and the tension
of the fieldmoves the field lines away from
|The "complete" solar wind - magnetosphere|
|Exhibition models of the four |
|Magnetic field measurements by |
Cluster at three different locations
around a reconnection region and
an artist's impression of how the
spacecraft moved though this region.
So now we have found the driver for the energetic processes which generate the aurora. In the next part we will take a look closer to Earth again, the region just above the aurora. We will try to follow the processes along the magnetotail with the THEMIS mission. And we will take a closer look at how the Earth's magnetosphere reacts at the dayside to changes in the solar wind magnetic field direction.