Changes to the Sun
There have also been some recent dramatic changes to the sun. The Ulysses spacecraft sent by NASA to measure the magnetic field of the sun found the magnetic fields of the poles enormously diminished. The magnetic poles of the sun usually reverse at the end of an eleven-year sunspot cycle. At the end of the most recent cycle, the poles only moved to the sun's equator and did not completely invert. This behavior alters everything that was previously believed about the sun's magnetic field. Effectively, the sun no longer has a single north or south magnetic pole; instead, it has four poles located in the equatorial regions.
X-Ray Flares
After the peak of the last eleven-year sunspot cycle in 1999, the sun has had a number of extremely large x-ray flare events. One of these, on April 2, 2001, was so large that it went off the scale completely. The previous scale ran to X-20 as the highest category, but this solar flare had to be categorized as an X-22 event. The x-ray burst was not in the direction of Earth, but a much smaller x-ray flare in 1989 was responsible for knocking out the whole Canadian power grid. If the X-22 event had hit Earth, possible consequences could have included major power outages, interruption of the Internet, damage to telecommunications and GPS satellites, and even the wiping of computer hard drives. The most powerful flare observed since then happened on November 4, 2003. It lasted eleven minutes and produced an x-ray flux of at least X-28, although some reports suggest it was much larger even than that.
The data gathered by the Ulysses spacecraft showed that the sun's magnetic field interacts with the rest of the solar system in a much more complex fashion than previously believed. NASA scientists determined that the polar magnetic field is much weaker than previously observed and the amount of cosmic dust entering the solar system is thirty times more than expected.
The Carrington Event
These recent events, though very significant, are not actually the largest solar flares ever recorded. That honor goes to a flare that happened on September 1, 1859. This has become known as the Carrington event after Richard Carrington, the young English astronomer who saw the event as it happened from his private observatory.
It was a remarkable piece of luck that he happened to be observing the sun at the particular moment that the flare erupted, because the event lasted for less than five minutes. In that time, a huge knot of sunspots appeared and generated a plume that was by far the biggest observed in the 160 years records have been kept.
Before dawn on the following day, a huge firework display of auroral lights bathed Earth, reaching as far south as the Caribbean. The rainbow-hued lights were so brilliant that it was said to be possible to read by them as if it were daylight. The Carrington event also caused major disruption to the telegraph system worldwide.
Conventional astronomy suggests that a flare of this size may only happen once every 500 years or so, but even greater flares have been observed on other stars. Some of these stellar megaflares have emitted quantities of radiation that would be likely to cause major loss of life on Earth.
