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article imageCould dark matter cause our extinction?

By Stephen Morgan     Feb 20, 2015 in Science
Dark matter could be the cause of mass extinctions, according to scientists who have analyzed the movement of the Earth through the region called the galactic disc.
Our Earth not only orbits the sun, but also orbits our galaxy along with the rest of the solar system. During this journey, the solar system passes through what is called the galactic disc and scientists are suggesting that this may be home to an extremely dense and powerful cluster of dark matter.
Dark matter has never been seen or conclusively proven to exist, but scientists believe it makes up a quarter of the universe and its huge gravitational force is what holds all things together. Without dark matter, the universe couldn't exist, according to current theories.
Now, in a scientific paper for the Monthly Notices of the Royal Astronomical Society, Professor Michael Rampino, a biologist at New York University, has suggested that the dense concentration of dark matter in our galaxy could be having an exceptionally strong effect on surrounding planets and comets, and this includes the Earth.
Our solar system passes through this region every 250 million years, but the Earth follows a "wavy" path, which brings it closer to the dense, dark matter every 30 million years. Rampino has calculated that this overlaps with the mass extinctions of the past, such as the dinosaurs 66 million years ago.
He believes that this dark matter pulls comets away from their normal paths and directs them towards Earth, therefore making collisions far more likely during this period. Science Daily explains,
"While traveling through the disc, the dark matter concentrated there disturbs the pathways of comets typically orbiting far from Earth in the outer Solar System.... This means that comets that would normally travel at great distances from Earth instead take unusual paths, causing some of them to collide with the planet."
Artist s rendering of meteor fireball impact
Artist's rendering of meteor fireball impact
Vojtech.dostal.. Licensed under Public Domain via Wikimedia Commons
However, Rampino also thinks that the dark matter could have a direct effect on Earth itself, reaching down into its inner core and causing rare and unusually severe geological events. Science Recorder says that,
"According to Rampino, every time Earth passes through the Galactic disc, dark matter also accumulates within the planet’s core. As the dark matter particles annihilate each other, an enormous amount of heat is produced. This heat could trigger volcanic eruptions, changes in sea level, and magnetic field reversals—events that appear to peak every 30 million years."
Such events would add to the possibility of mass extinctions. The eruption of super volcanoes, for example, could lead to the equivalent of a nuclear winter. The ash blown into the atmosphere would block out all sunlight, resulting in the destruction of the world ecosystem and now, modern day agriculture. Large areas of the world would become flooded and uninhabitable. Animals would die off on mass and the survival of the human race could be put in doubt.
Likewise, the movement of tectonic plates would cause massive earthquakes along the major fault lines around the world and some scientists think that a magnetic field reversal — when the Earth's north and south poles flip — could leave us unprotected from solar radiation, which would punch holes in the ozone layer and unleash a cascade of chemical reactions. It has even been suggested that the last reversal caused the demise of the Neanderthals.
However, this may not just be a future possibility. Rampino suggests that we may still be experiencing the effects of the last time Earth passed through the galactic disc.
The Mail Online quotes the professor as saying,
"the Earth could be still be experiencing the effects of the most recent encounters and may even result in future extinctions." According to him, "the solar system is thought to have last passed through the plane of the Milky Way around two to three million years ago and this might explain a cluster of recent impact craters and a minor extinction event in the Pliocene." He added that "several researchers have suggested that we are in a comet shower at present." and that "we might expect enhanced rates of large body impacts."
Rampino thinks that the research could potentially change the way we understand geological and biologic developments on Earth. His new findings are backed up by Lisa Randall and Matthew Reece at Harvard University in Massachusetts, who last year also computed that the solar system passes through a dark matter disc every 35 million years
Rampino said: "We are fortunate enough to live on a planet that is ideal for the development of complex life. But the history of 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."
More about Dark matter, Milky way, Galaxy, mass extinction, Comets
 
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