Every 250m years the sun, with its entourage of planets, completes a circuit of the Milky Way. Its journey around its home galaxy, though, is no stately peregrination. Rather, its orbit oscillates up and down through the galactic disc. It passes through that disc, the place where most of the galaxy’s matter is concentrated, once every 30m years or so.



More…Dark matter affects normal material through the influence of gravity. New analysis shows that gravitation could perturb the Oort Cloud surrounding the Solar System, sending comets to rain down on the inner solar system, and could also affect the behavior of the Earth’s core. Either of these influences could result in mass extinctions, researchers theorize. It is possible that the asteroid strike that ended the age of dinosaurs may have been sent to Earth during one of these passes through the central disk of the Milky Way.

“We are fortunate enough to live on a planet that is ideal for the development of complex life, ” Professor Michael Rampino, a biologist at New York University commented. “But the history of the Earth is punctuated by large scale extinction events, some of which we struggle to explain. It may be that dark matter – the nature of which is still unclear but which makes up around a quarter of the universe – holds the answer. As well as being important on the largest scales, dark matter may have a direct influence on life on Earth.” In the future, he suggests, geologists might incorporate these astrophysical findings in order to better understand events that are now thought to result purely from causes inherent to the Earth. This model, Rampino adds, likewise provides new knowledge of the possible distribution and behaviour of dark matter within the Galaxy.

Rampino’s work adds to other theorists who have linked our Solar System’s path around the galaxy to Earth-based extinction events. In 2008, Cardiff University scientists said the Earth’s galactic cycle “ is a beautiful match with the mass extinction events that occur periodically.

Rampino’s model of dark matter interactions with the Earth could have a broad impact on our understanding of the geological and biological development of Earth, as well as other planets within the Galaxy.

If Dr Rampino does turn out to be right, it will be an example of how important dark matter, ethereal though it be, really is. There is a tendency, even among physicists, to refer to atomic matter as normal, and dark matter as strange. This would be a reminder that it is dark matter, not the “normal” sort, which is actually in charge.



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