This web page displays dynamic modeling of the Earth's
bow shock and magnetopause.
Real time data from the ACE spacecraft (top two panels) are used
to predict the shape and location of these boundaries at the present
time and into the near future (The time is Universal Time as
measured at Greenwich, England.
Click here for information on
conversions to local time).
In the figure to the right, the Earth is in the center,
and is illuminated from the left by the Sun (not shown).
In this view, we are looking down upon the North pole;
thus the figure represents the equatorial plane.
The solar wind emanating from the Sun is super-magnetosonic
with respect to the Earth, so that a shock wave is formed.
As the solar wind flows through the shock it is slowed down,
and the pressure of the solar wind is balanced by the
pressure from the Earth's magnetic field. The boundary at which
this pressure balance is achieved is called the magnetopause.
The ACE spacecraft monitors the solar wind from a position about 200
Earth radii (RE) sunward of the Earth. The real time solar wind data
from this spacecraft allows us to predict what will happen at the Earth
many minutes before the solar wind actually reaches us. Important solar wind
values obtained from the ACE observations include the z-component of
the interplanetary magnetic field (Bz) measured in units
of nano-Tesla, and the dynamic pressure (also called the momentum flux)
of the solar wind, measured in units of nano-Pascal.
Geosynchronous orbit (where many weather and
communication satellites orbit) is depicted by the green dashed circle.
Here are all the gory details.
This movie is updated every five minutes
(unless there is an extended data gap in the ACE observations).