A Stranger Sun

OUR NORMALLY placid Sun is behaving in a most unexpected way. Two tremendous recent storms have demonstrated exceptional violence. According to levels of a radioactive isotope found in ice cores, there have been more sunspots since the 1940s than at any time in the last 1,100 years. Even the great solar storm of 1859 has been surpassed in intensity by the space tempests of 2003. In September 145 years ago, the still primitive telegraph wires in both America and Europe shorted out, causing numerous fires. So powerful were the Northern Lights that they were seen as far south as Rome and Havana.

The Sun - 1.2 million Earths could fit inside it!

The 2003 storms, although doing much less damage, disproved the conventional belief that the Sun remains more or less constant over very with small but regular fluctuations over periods of 11 years. It goes without saying that this finding must say a great deal about the causes of global warming. And it also, unfortunately, goes without saying that believers in man-made global warming will probably ignore it. While pondering this mystery, let us look at some statistics about the Sun – fascinating both because it gives us life and because of its place in the universe. Its energy is equal to 383,000 billion trillion watts (a bright light bulb, by comparison, is 100 watts.) It comprises 99.86 of all the mass in the solar system. Even mighty Jupiter and Saturn are mere wisps of gas compared with it. With a diameter of 870,000 miles, 1.2 million Earths could fit inside it. Most fascinating (to me anyway) are the ways that the Sun would appear to observers at different distances. To someone standing on Mercury, it would fill a quarter of the sky. But to an astronaut standing on Pluto, at the opposite extreme of the solar system, it would be just a bright point of light, giving out no heat, 1,600 times fainter than when seen from Earth. There would be no glare. The great haze of the Milky Way would be easily visible beside it. Let us go still further into space and look back at the Sun. At one light-year, 1,700 times more distant than Pluto, it would be the brightest star in the heavens, but still just a star. Its disc could not be made out with the naked eye. From a planet circling Proxima Centauri, four and third light - years away, it would be just another medium-bright star in Cassiopeia on the edge of the Milky Way. But the stellar background would be utterly different. Up to 100 light-years away, it would be a very faint star with nothing remarkable about it at all. And from 1,000 light-years it would be utterly invisible, lost in the galactic haze. So what are we to make of its inconstancy, so recently revealed? Nobody is suggesting that the Sun is likely to go nova or become violently unstable – after all it has nurtured life for nearly four billion years. Still, it might be a good idea to re-examine all Sun-like stars, comparing them with pictures taken a century ago, to see if any of them show similar small changes in radiation..