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Into the dark side

The Milky Way as seen over the desert of Bardenas in Spain The Milky Way as seen over the desert of Bardenas in Spain Inigocia
11 Apr
Every 30 million years or so, the Earth passes through the most crowded section of the galactic disc. Mass extinction events and radical changes to the Earth’s geology follow

New research has suggested that what the Earth encounters when it enters the Milky Way’s crowded section of the galactic disc – namely dark matter – causes changes deep within the planet’s core.

‘When the Earth passes through [that part of] the disc, it might encounter dense clumps of invisible dark matter,’ says professor Michael Rampino, a biology professor at New York University, whose research shows a correlation between mass extinctions, geological change and the Earth’s orbit.

‘Dark matter is slowed by collisions with the Earth, loses energy and spirals into the Earth’s core,’ says Rampino. ‘If the particle is its own antiparticle they will annihilate each other, giving off energy.’

As the particles annihilate each other, immense heat is created in the Earth’s core. This heat triggers volcanic eruptions, mountain building, changes sea levels and can even flip the Earth’s magnetic fields.

A passage through dark matter also changes pathways for comets orbiting far from Earth in the outer Solar System. Comets that usually take orbits far from Earth can be pushed onto a collision course.

‘As well as being important on the largest scales, dark matter may have a direct influence on life on Earth,’ says Rampino. These changes apparently take place over a long time period and the professor warns that it may not be possible to predict encounters with dense clumps of dark matter.

‘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,’ says Rampino. We can rest easy for a while though. Earth’s last journey through the disc was three million years ago.

This article was published in the April 2015 edition of Geographical Magazine

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