Spiral Pattern

Spiral Pattern

Light Is Also Wave

The speed of any given star around the center of the Galaxy in generally not the same as that of the spiral pattern.

The Sun has been in and out of spiral arms often in the twenty times it has gone around the Milky Was at 200 kilometres per second (roughly half a million miles per hour). On the average, the Sun and the planets spend forty million years in a spiral arm, eighty million outside, another forty million in, and so on. Spiral arms outline the region where the latest crop of newly hatched stars in being formed, but not necessarily where such middle-aged stars as the Sun happen to be. In this epoch, we live between spiral arms.

The periodic passage of the solar system through spiral arms may conceivably have had important consequences for us. About ten millions years ago, the Sun emerged from the Gould Belt complex of the Orion Spiral Arm, which is now a little less than a thousand light-years away (interior to the Orion arm is the Sagittarius arm; beyond the Orion arm is the Perseus arm).

Light is also a wave. A Heart Planet by © Elena

When the Sun passes through a spiral arm it is more likely than it is at present to enter into gaseous nebulae and interstellar dust clouds and to encounter objects of substellar mass. It has been suggested that the major ice ages on our planet, which recur every hundred million years or so, may be due to the interposition of interstellar matter between the Sun and the Earth.

W. Napier and S. Clube have proposed that a number of the moons, asteroids, comets and circumplanetary rings in the solar system once freely wandered in interstellar space until they were captured as the Sun plunged through the Orion spiral arm. This is an intriguing idée, although perhaps not very likely. But it is testable. All we need do is procure a sample of, say Phobos or a comet and examine its magnesium isotopes.

The relative abundance of magnesium isotopes (all sharing the same number of protons, but having differing numbers of neutrons) depends of the precise sequence of stellar nucleo-synthetic events, including the timing of nearby supernova explosions, that produced any particular sample of magnesium. In a different corner of the Galaxy, a different sequence of events should have occurred and a different ration of magnesium isotopes should prevail.