14 DAY TRIAL // A team of investigators shows that it is possible in theory to produce maps of a large number of galactic clouds, but warns that the road to obtaining the representations is long and fraught with risks of error.
Since it first appeared, some 4.6 billion years ago, the Sun has been orbiting the central core of the Milky Way once every 220 million years or so.
As this happens, the star passes through a large number of galactic dust and gas clouds, all of which exert their influence on the solar system, and our planet implicitly.
In addition to that, the cosmic rays that permeate the galaxy can attack the inners solar system as well. Usually, the Sun's radiation, called the heliosphere, protects us from such negative effects.
Still, when they do make their way into the atmosphere, the rays slam into existing atomic nuclei, creating exotic compounds, such as beryllium-10, chlorine-36 and carbon-14.
After conducting analysis of the Earth's geomagnetic record, experts proposed that variations in the amount of cosmic rays should be clearly visible within the ancient “data system.”
They therefore assumed that the amount of cosmic rays which made its way to the paleorecord was dependent on the intensity of Earth's magnetic defense shield, called the magnetosphere.
But, when cross-referencing past waxing and waning of the shield, experts noticed a number of inconsistencies. “Several anomalies are found in these comparisons,” the team says.
The work was conducted by University of Chicago expert Priscilla Frisch, in collaboration with Dartmouth College scientist Hans-Reinhard Mueller, who now think they may know why this situation developed.
The investigators say that it is not unreasonable to think that events and phenomena other than the heliosphere and the magnetosphere can affect the amount of cosmic rays reaching Earth.
They say that the clouds through which the Sun passes as it moves within the Milky Way may have exerted an influence on the geomagnetic paleorecord as well, Technology Review reports.
If so, Frisch and Mueller say, then it could be that associating the anomalies in the paleorecord with astronomical data on the cosmic clouds the Sun most recently passed through could allow astronomers to create new maps of the cosmic structures.
Details of the new investigation appear in a paper called “Time-variability in the Interstellar Boundary Conditions of the Heliosphere over the past 60,000 years: Impact of the Solar Journey on the Galactic Cosmic Ray Flux at Earth.
The work is published in the online journal arXiv.