Earth's magnetic field, which protects the planet from huge blasts of deadly solar radiation, has been weakening over the past six months, according to data collected by a European Space Agency (ESA) satellite array called Swarm. Earth has settled in the last 20 million years into a pattern of a pole reversal about every 200,000 to 300,000 years. A reversal happens over hundreds or thousands of years. Magnetic fields morph and push and pull at one another, with multiple poles emerging at odd latitudes throughout the process. Scientists estimate reversals have happened at least hundreds of times over the past three billion years. And while reversals have happened more frequently in "recent" years.
Sediment cores taken from deep ocean floors can tell scientists about magnetic polarity shifts, providing a direct link between magnetic field activity and the fossil record. The Earth’s magnetic field determines the magnetization of lava as it is laid down on the ocean floor on either side of the Mid-Atlantic Rift. This is where the North American and European continental plates are spreading apart. As the lava solidifies, it creates a record of orientation of past magnetic fields. The last time that Earth's poles flipped in a major reversal was about 780,000 years ago. The fossil record shows no drastic changes in plant or animal life. Deep ocean sediment cores from this period also indicate no changes in glacial activity, based on the amount of oxygen in the cores. This is also proof that a polarity reversal would not affect the rotation axis of Earth, as the planet's rotation axis tilt has a significant effect on climate and glaciation and any change would be evident in the glacial record.
The science shows that magnetic pole reversal is – in terms of geologic time scales – a common occurrence that happens gradually over millennia. While the conditions that cause polarity reversals are not entirely predictable, the north pole's movement could subtly change direction.
If the magnetic field of the Earth suddenly changed, the consequences would be fascinating. For life, we can see from the fossil record that the past field changes had no significant effect on living organisms. This is most curious because the field reversal. You might expect the field to go to zero strength for a century or so.This would let cosmic rays freely penetrate to the Earth's surface and cause mutations. This seems not to have had much effect in the past, so we probably don't really know what is going on during these field reversals. There have been a dozen of them over the last few million years, documented in the rock which has emerged and solidified along the mid-Atlantic Ridge where continental plates are slowly separating. These epochs form parallel bands all long the ridge where the rock has stored a fossilized image of the local orientation of the Earth's magnetic field for the last few million years.
Magnetic field wandering would let the aurora borealis occur at any latitude, but other than that there would be no noticeable effects other than changes in the amount of cosmic rays that penetrate to the ground. Even this effect is minimal because we can visit the Arctic and Antarctic and only receive a slight increase in cosmic rays. So long as the strength of the field remains high during this field wandering event, the effects should be pretty benign.
2) It is believed that the solid inner core has large metallic crystals sticking out of it. What are these crystals called? Explain the evidence that suggests to scientists they are there.
The large metallic crystals are called Iron Crystals. Scientists discovered it in 1995 with a sophisticated computer model of Earth's inner core. What scientists have pieced together…