Nearly everybody knows that the sun is much bigger than the earth. The sun's diameter is about a hundred times that of the earth, and the sun's volume is about a million times the volume of the earth.The July 11, 2008, issue of Science contains a report on the explosion of a star having a diameter about a thousand times that of the sun, and a billion times its volume. Here's a diagram showing size scales, with the orbits of the inner planets deep inside the star:
The inner solar system, out to about Jupiter, could exist inside the volume of this star. In the diagram, the sun would be in the center, too small to be seen, and Jupiter would be orbiting near the surface the star. The report in Science says that the core of this large star collapsed -- i.e., it fell inward upon itself to form a black hole or at least a neutron star that would be about as big as Washington, D.C., and weighing about three times as much as the sun. The star itself had a mass some 10 to 20 times that of the sun. The star's core would have been made mostly of iron, with, I think, large amounts of manganese, chromium and vanadium.
This star was in a galaxy that is reported to be about a billion light years away (Z = 0.1854), which means that the explosion happened about a billion years ago, back when our ancestors were bacteria in the ocean. News of this explosion was in transit till early in 2008, when the light arrived. When the iron core fell inward upon itself, there was a great explosion in the form of an outward-expanding shock wave. According to the report in Science, the shock wave moved outward at about 1/20th of the speed of light; a traveler going at that speed would be able to circle the earth in three seconds. The star was so big, though, that some 10 hours passed before the shock wave got its the surface. The report says that an observer watching from outside the star would have seen no change in the star till some hours after the core collapse had taken place. This supernova explosion was reported in Science because of the "radiative precursor," which had been theorized but not previously seen. As I interpret the report, light was "diffusing" ahead of the shock wave, going maybe twice as fast as the photons rattled their ways outwards among the atoms of the star's outer envelope, as it is called. The radiative precursor apparently lit the star up in ultraviolet light for several hours before the shock wave got to the surface and blew the star apart. This all happened long ago. Civilizations may have been killed off in neighboring star systems. Reading about this sort of thing makes me think that other supernova explosions in galaxies that are closer to the Milky Way might have ejected atoms that have traveled across intergalactic space to be on the earth now, and in our bodies.
Bob |
