NASA: Earth may have 'hairy' dark matter

This illustration shows Earth surrounded by theoretical filaments of dark matter called "hairs." (Credit: NASA/JPL-Caltech)

Clearly, facial hair really is extremely popular at the moment. New research suggests that even the solar system may be ‘hairier’ than originally thought.

A new study by Gary Prézeau of NASA's Jet Propulsion Laboratory in Pasadena, Calif. proposes the existence of long filaments of dark matter, or "hairs." Prézeau’s study is publishing this week in the Astrophysical Journal.

“Dark matter is an invisible, mysterious substance that makes up about 27 percent of all matter and energy in the universe,” explained NASA, in a statement. “The regular matter, which makes up everything we can see around us, is only 5 percent of the universe. The rest is dark energy, a strange phenomenon associated with the acceleration of our expanding universe.”

NASA added that neither dark matter nor dark energy has ever been directly detected, although a number of experiments are trying to unlock the mysteries of dark matter, whether from deep underground or in space.

“Based on many observations of its gravitational pull in action, scientists are certain that dark matter exists, and have measured how much of it there is in the universe to an accuracy of better than one percent,” explained NASA. “The leading theory is that dark matter is ‘cold,’ meaning it doesn't move around much, and it is ‘dark’ insofar as it doesn't produce or interact with light.”

The space agency added that galaxies, which contain stars made of ordinary matter, form because of fluctuations in the density of dark matter. Gravity, it noted, acts as the glue that holds both the ordinary and dark matter together in galaxies.

Research undertaken in the 1990s and the last decade found that dark matter forms "fine-grained streams" of particles.

"When gravity interacts with the cold dark matter gas during galaxy formation, all particles within a stream continue traveling at the same velocity," said Prézeau, in the NASA statement.

Using computer simulations Prézeau studied what happens when dark matter particle “streams” approach Earth. “His analysis finds that when a dark matter stream goes through a planet, the stream particles focus into an ultra-dense filament, or ‘hair,’ of dark matter,” explained NASA. “In fact, there should be many such hairs sprouting from Earth.”

The computer simulations also showed that changes in density found inside Earth - from the inner core, to the outer core, to the mantle to the crust - would be reflected in the hairs. Scientists noted that the hairs would have "kinks" in them that correspond to the transitions between the different layers of Earth.

“Theoretically, if it were possible to obtain this information, scientists could use hairs of cold dark matter to map out the layers of any planetary body, and even infer the depths of oceans on icy moons,” NASA noted.