## Tuesday, 16 December 2008

### Turn A Light On In Heaven For Me

Outer space is black. When we look at the night sky we can see stars which offer us a pin-prick of light, but they do not swathe the Universe in light. Our own Sun bathes our planet with visible light, but outer space remains empty and black. As the Earth revolves around the Sun we have night and day. As the energy from the Sun reaches half the planet it is transformed into visible light. The other half revolves in darkness, and is offered light only by the moon. If light from the Sun always travelled as visible light, then surely the Universe would be awash with light. How does light (electromagnetic radiation) travel from the Sun to the Earth?

The average distance of the Sun from the Earth is 150 million km. Light, travelling at the speed of light takes about eight minutes to reach the Earth. We can illustrate this passage of light as a frequency. If we assume a frequency is one cycle per second (or 1Hz), then we can create the frequency of light in one second. The wavelength of this frequency would equal the distance travelled by the speed of light (300,000 km/s) - so the wavelength would be 300,000 km. It would take light travelling from the Sun 500 seconds to reach the planet. This frequency could be written as 0.002 Hz. Therefore the size of the wavelength travelling from the Sun shall be much bigger, around 500 times bigger. A frequency of 0.002Hz will give us a wavelength that is a total of 150 million km in circumference.

Is the Earth simply bathing in this extremely low frequency of 0.002 Hz? Somehow then it must convert it into the various shorter wavelengths of electromagnetic radiation that we are more familiar with. I'm reminded here of a lamp in an AC circuit. A lamp converts the longer wavelengths of electrical energy into the much shorter wavelengths of visible light. In doing so it increases the velocity of the charge flow (current). What comparisons, if any, can be made between a simple household circuit, and the relationship between the Sun and the Earth?

Many thanks: