A strong geomagnetic storm is set to hit the earth today. This storm is the strongest one in seven years but is expected to only have a minor effect on the disruption of satellites, power networks, and navigation systems. The geomagnetic storm is cause by a coronal mass ejection (CME) which happens when a cloud of magnetised plasma from the Sun’s atmosphere (known as the corona) is ejected into space due to a solar flare. The ejection is traveling at a speed of 1400 km per second towards the earth. Once the CME reaches the earth, it causes geomagnetic storms.
The storm is forecasted by NOAA to be a G-2 or G-3 on their five level scale and to last for one day. Space weather measurements can be accessed from the SOHO (Solar and Heliospheric Observatory) space weather page.
Geomagnetic storms disrupt global navigation satellite systems by causing variations in the density of the ionosphere (earth’s upper atmosphere), which causes the GPS signals to scintillate. A research paper in Anales Geophysicae from 2009 looked at the effects of geomagnetic storms on GPS based navigation:
Changes in the electron density, due to space weather activity, can change the speed at which the radio waves travel, introducing a propagation delay in the GPS signal.