Tomorrow is winter solstice and the sun will start to return to the north. This solar event is celebrated across the northern hemisphere and has been celebrated throughout time. I love light. I love sunshine. I love winter solstice. Here's my 2011 celebration of light.
Film in a movie camera moves at 24 frames per second. (proper film - does not apply to digital film) The shutter on the movie projector closes between each frame and causes darkness on the screen. This happens so quickly that our minds don't detect the darkness, we just interpret the change in frames, or the changes in the pictures as continuous motion. The shutter is only open for 1/50 of a second to reveal each picture. The shutter is open 24 times and closed 26 times per second. This means we sit in the dark for more of the movie than we sit in the light. If the movie is 2 hours long, we will watch pictures for 58 minutes and watch darkness for 62 minutes.
In space, molecules of gas and dust grains bump into each other. Eventually, they form a cloud. The cloud starts to spin and it spins faster and faster and at some point the temperature at the center becomes high enough for a star to "turn on". Under the three stars in Orion's belt is a faint greenish haze. This is known as Orion's nebula. A nebula is a baby star. It takes light 15,000 years to reach the earth from the nebula. So the light we see from it now is actually energy that was emitted 15,000 years ago (13,000 B.C.). If you were to travel to the nebula at 65 miles per hour, it would take you 145 trillion years to get there and there would be 33,376,456,000,000,000,000 lines on the road on the way. Even at that distance - Orion comes to play in our planet's winter sky and that greenish haze taunts us. Is it possible that the nebula has grown up and turned on - maybe it's a star by now. But we might not know for another 14,599 years.
It takes 8 minutes for light to travel from the sun to the earth. The sun is in the sky 8 minutes before sunrise and leaves the sky 8 minutes before sunset.
It's hard to imagine that the sun which is 149 million kilometers away from the earth can make the summer so hot. But if you know that it has a temperature of 27 million degrees farenheit at its core, it is a little easier to understand. If you are sitting outside in the sun, you can detect three aspects of the sun's light. Photons light up your surroundings so you can see. Infrared rays warm your skin. Ultraviolet rays brown your skin.
Visible light - rather, light we can see with our eyes - is only part of an array of light made up of wavelengths that our eyes can't detect. Examples of light we can't see are radio waves, infrared waves, ultraviolet waves, X-rays, etc. If the entire spectrum of light was spread across a football field, the light we can see with our eyes would take up less space than a blade of grass. There is a lot we don't know we don't know.
Visible light is made up of particles. The particle for the color red is a different size and shape than the particle for green, or purple, etc. Most of the light particles coming from the sun pass through the earth's atmosphere and are absorbed into the ground. The only particles that don't pass through are the blue ones. The shape of a blue light particle matches the shape of oxygen molecules in the air. The molecules act as a mirror, reflecting the blue particles and scattering them in the sky.
Light travels at a constant speed, which is 300,000 kilometers per second. Einstein figured out that if you were able to travel at that speed, time would occur at a slower rate. Time would be "relative" to your speed. Light is constant. Time varies.
Light is constant. Time varies. No wonder we crave the light.
Happy Solstice.
