A fast-flowing river of liquid iron has been discovered recently in the outer core of the Earth, just under Alaska and Siberia.

The "jet stream" was detected using European Space Agency's (ESA) latest trio satellite called "swarm," which helps create an x-ray view of the planet by measuring magnetic field variations up to 3,000 feet below the Earth's surface.

According to New Scientist, the 420-kilometer wide jet stream has been speeding since 2000. It is now accelerating with speeds between 40 and 45 kilometers per year -- three times faster than typical speeds of liquid in the outer core.

As per Science Alert, when the scientists were looking at the data gathered by the satellite, they noticed that there were strong lobes of magnetic flux beneath Alaska and Siberia. They also notice that the lobes are not stagnant, but are moving.

Because their motion could originate only from the physical movement of molten iron, the strong lobes of magnetic flux were used as a guide to determine how the jet stream flows. And it is most likely that when the iron moves, the magnetic field goes along with it.

The scientists say the jet stream probably aligns to a boundary between two different regions in the core; although they are not sure whether how deep the jet stream goes.

Dr. Phil Livermore from Leeds University, UK, and the lead author on the journal paper told BBC News: "It currently wraps about 180 degrees around the tangent cylinder. Although observations only constrain the jet stream on the edge of the core, our theoretical understanding suggests that the jet could in principle go very deep indeed - possibly in fact all the way down to the edge of the core in the southern hemisphere (i.e. at the other end of the tangent cylinder)."

The new data provides answer as to why the planet's magnetic field has been changing. Magnetic fields keep us safe from solar winds. Earth's magnetic field is influenced by the activities happening in the core, mantle and crust.

The scientists are yet to look for explanations as to why the flow is accelerating, but they are certain that is a natural phenomenon that has been happening billions of years ago. The study was published in Nature Geoscience.