Read Online Death from the Skies! by Ph. D. Philip Plait - Free Book Online Page B
Authors: Ph. D. Philip Plait
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magnetotail, a lot of energy is released. Charged subatomic particles flow along the lines, down toward the Earth. Accelerated by the magnetic field, they slam into the Earth’s atmosphere, ionizing molecules in the air, stripping them of their electrons. When the electrons recombine with atoms, light is emitted with characteristic colors: oxygen molecules give off red light, and nitrogen green. 15 Since this happens where the magnetic field lines of the Earth drop down into the atmosphere near the poles, in general people living at extreme northern and southern latitudes who venture outside during such an event are met with a brilliant display of aurorae— aurora borealis for the north, and aurora australis for the south. In a particularly powerful event, it’s possible to see them at mid-latitudes as well; the 1859 white-light solar flare event spawned a massive CME that caused aurorae to be seen as far south as Puerto Rico.
Aurorae have mesmerized people for millennia, and it was only recently understood that they are harbingers of vast unseen forces at play high above our heads, forces that trace their origins back to our nearest star and to the unimaginable violence wreaked there.
The effects of a big CME are far larger than a simple light show, however. For one, they compress the Earth’s magnetosphere. A satellite orbiting above the Earth inside the protective magnetic field may suddenly find itself exposed to the full brunt of the CME. The incoming radiation can then fry it.
The Earth is not the only planet affected by the Sun. This ultraviolet image from the Hubble Space Telescope shows an aurora at Saturn’s north and south poles. Any planet with a magnetic field can experience magnetic storms when the Sun is active.
J. T. TRAUGER (JET PROPULSION LABORATORY) AND NASA
There are even more profound effects from a big CME, ones that affect us directly, even on the surface of the Earth.
Remember that a changing magnetic field can induce a current? Well, when the magnetic field of the Earth changes rapidly because of a CME impact, any nearby conductor can suddenly find itself dealing with a huge surge of current.
There are plenty of such conductors on the surface of the Earth . . . like the entire North American power grid. Think of it: millions of miles of wires, all designed specifically to carry current from one place to another! Under normal operating conditions, these wires are easily able to carry a large amount of current, making sure that electricity generated at, say, Hoover Dam can be sent to Los Angeles to power someone’s margarita blender.
But these wires are very sensitive to solar storms. For one thing, these storms add a huge load to the system. For another, current heats up wires, causing them to sag. This process is well understood by electrical engineers and under normal operating conditions the system is designed to withstand it. However, a big pulse of current caused by a storm can add to the load already there, causing lines to heat up too much and break. For a third, over the years, more power generators have been added to the grid, but not more wires. As time has gone on, American power demands have grown. The wires were originally built to hold quite a bit of current, but in many cases they are operating closer and closer to their full capacity. A big surge can blow out the huge transformers vital to making sure the high-voltage electrical current in wires gets dropped to much lower voltages before going into your house. These transformers are expensive (some are as big as houses) and losing them can mean whole cities might go without power for great lengths of time.
Case in point: on March 6, 1989, an ugly and enormous group of sunspots rotated into view on the solar surface. Spanning 43,000 miles, they had already spawned many flares that were detected even though the spots themselves were on the far side of the Sun. Astronomers expected the worst.
They got it. Over a
Aurorae have mesmerized people for millennia, and it was only recently understood that they are harbingers of vast unseen forces at play high above our heads, forces that trace their origins back to our nearest star and to the unimaginable violence wreaked there.
The effects of a big CME are far larger than a simple light show, however. For one, they compress the Earth’s magnetosphere. A satellite orbiting above the Earth inside the protective magnetic field may suddenly find itself exposed to the full brunt of the CME. The incoming radiation can then fry it.
The Earth is not the only planet affected by the Sun. This ultraviolet image from the Hubble Space Telescope shows an aurora at Saturn’s north and south poles. Any planet with a magnetic field can experience magnetic storms when the Sun is active.
J. T. TRAUGER (JET PROPULSION LABORATORY) AND NASA
There are even more profound effects from a big CME, ones that affect us directly, even on the surface of the Earth.
Remember that a changing magnetic field can induce a current? Well, when the magnetic field of the Earth changes rapidly because of a CME impact, any nearby conductor can suddenly find itself dealing with a huge surge of current.
There are plenty of such conductors on the surface of the Earth . . . like the entire North American power grid. Think of it: millions of miles of wires, all designed specifically to carry current from one place to another! Under normal operating conditions, these wires are easily able to carry a large amount of current, making sure that electricity generated at, say, Hoover Dam can be sent to Los Angeles to power someone’s margarita blender.
But these wires are very sensitive to solar storms. For one thing, these storms add a huge load to the system. For another, current heats up wires, causing them to sag. This process is well understood by electrical engineers and under normal operating conditions the system is designed to withstand it. However, a big pulse of current caused by a storm can add to the load already there, causing lines to heat up too much and break. For a third, over the years, more power generators have been added to the grid, but not more wires. As time has gone on, American power demands have grown. The wires were originally built to hold quite a bit of current, but in many cases they are operating closer and closer to their full capacity. A big surge can blow out the huge transformers vital to making sure the high-voltage electrical current in wires gets dropped to much lower voltages before going into your house. These transformers are expensive (some are as big as houses) and losing them can mean whole cities might go without power for great lengths of time.
Case in point: on March 6, 1989, an ugly and enormous group of sunspots rotated into view on the solar surface. Spanning 43,000 miles, they had already spawned many flares that were detected even though the spots themselves were on the far side of the Sun. Astronomers expected the worst.
They got it. Over a
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