Every few hundreds of years, our compasses’ little arrow does an about-face and points in a different direction. That’s because the Earth’s magnetic field actually flips its polarity, meaning instead of gravitating to point north, your compass would direct you south. The magnetic field may be invisible, but it’s always in a state of flux, and in 2013 three elongated satellite watchdogs were unleashed to monitor magnetic signals all over the planet. But the trio would mysteriously black out over the equator, and just last month a study revealed what the troublemaker was: ionospheric storms.
The trio of spacecrafts, named the Swarm satellites, have GPS receivers onboard so that operators back at the European Space Agency (ESA) can maintain their orbits and track their measurements. Shaped like space vacuums, they traverse in a constellation, snuffling around to figure out why our magnetic field is weakening, among other research.
But in their first year of orbit, the GPS links broke a whopping 166 times when Swarm flew near Africa and South America.
Magnetic signals can emerge from many Earthly sources, from its core and oceans to its ionosphere. The Earth’s ionosphere is immense, stretching from about 30 miles (about 48 km) above the Earth’s surface to the edge of space at about 600 miles (965 km), and it can grow and shrink as the sun’s and other cosmic radiation ebbs and wanes. In case you’ve forgotten what ionizing means, it’s when an atom or molecule is converted into an ion, usually when an electron is separated from an atom.
In this region, sunlight breaks up atoms, and a “thunderstorm” can scatter these newly freed electrons. The squalls rage when the electrons undergo a huge or fast change, according to an ESA release. This creates bubbles with little to no ionized material — and that’s what disturbs GPS signals, the paper suggests. Researchers noted that 161 of the events happened to occur during ionospheric storms. Using that information, they’ve fine-tuned the Swarm GPS receivers to result in fewer of these signal losses.
Storms in the mesosphere, the third layer of Earth’s atmosphere that the the ionosphere overlaps, are pretty impish, too. Because they live at such a height that’s difficult to study, different types of lightning went unnoticed for decades until they were caught on film in the late 1980s. Their names range from mythical creatures like sprites and elves because of their (still) mystical nature.