One of the NASA spacecraft orbiting the Earth is called the Global-scale Observations of the Limb and Disc or GOLD. The spacecraft has been in orbit, providing a view of the Earth’s atmosphere for a long time. It has revealed surprising behavior in charged particles circling the equator of the Earth.
GOLD is in a geostationary orbit allowing it to stay in the same spot as the Earth rotates. A geostationary orbit allows the satellite to scan the same area and watch for changes over time. GOLD is specifically focused on parts of the upper atmosphere from an altitude of about 50 to 400 miles above the surface.
Two of the layers the satellite observes are the thermosphere and the ionosphere. The ionosphere is made up of charged particles. Particles in the ionosphere react to both magnetic and electric fields that extend into the atmosphere and near-Earth space. The layers of the upper atmosphere are shaped by several factors, including geomagnetic storms and the weather here on Earth.
One of the areas that the satellite observes are bands known as the Equatorial Ionization Anomaly or EIA for short. EIA changes drastically depending on conditions in the ionosphere, and the bands can move position. GOLD allows scientists to observe these bands over the long term. Thanks to its observations, scientists were able to observe something that challenged previous theories. In late 2018, the southern band particles drifted more southward while the northern band remained steady.
Before that observation, theories held that quick changes in the bands would be symmetrical. In this instance, it took only two hours for the bands to move compared to that type of movement typically taking as long as eight hours. The exact cause of the asymmetrical drift observed is still unknown.