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Sending all of you and those you care for the gifts of light and love, peace and joy for the season – and every day.


Lunatics and coral reefs

Christmas day was the last full moon of the year, known as the Cold Moon.

Although moonlight is dim, around 6 lux, the full moon is traditionally associated with strange and supernatural events, the origin of the term lunatic – Does the Moon Affect Humans?

Although there is no evidence that you are more likely to go mad today, analysis supports this basic principle: we go to bed later, sleep less and enjoy less NREM sleep in the days before the full moon – even when we live in an urban environment where light pollution will overwhelm the subtle glow – Moonstruck sleep: Synchronization of human sleep with the moon cycle under field conditions. 

This influence reaches into the depths of the sea to trigger the spawning of coral reefs – Light-Responsive Cryptochromes from a Simple Multicellular Animal, the Coral Acropora millepora.


Twinkle Twinkle Little Astrophysics Formula…

As you have a little more time this week, I invite you to take a stroll and look up at the night sky. If you’re lucky enough to live somewhere that gets properly dark, you’ll be treated to a twinkling display of of the physics of light. Here’s a fascinating article about how you can use the way your eyes work to see dim objects like stars more clearly.

Essentially the rods (packed around the edges of your retina, the light-sensing membrane in the back of your eye) perform better in dim light than the central, colour vision zone called the fovea – where the cones are. So if you look slightly to one side of the object you’re trying to see (8-12 degrees), and wait for your eyes to adapt or become used to the darkness, you will be able to see dim stars that you would miss when you’re looking straight at them. 

Stars twinkle for two reasons.

The first, well-established reason is that the winds in the earth’s atmosphere bends the beam on its way to us, like water from a hose on a stormy day.

The second, a discovery published in July this year, is that the outer shell of the star itself is pulsing with gravitational waves that create ripples in the photon emissions before they even set off to find your eyes, light years away here on earth –  The photometric variability of massive stars due to gravity waves excited by core convection.

Another reason to switch off your lights at night and encourage local councils and businesses to do the same so we too can marvel at the magic that entranced the magi.


Pub Quiz factoids…

1.  What’s a Jiffy?

  • The time it takes for light to travel one cm in a vacuum, which is about 33.3564 picoseconds.

2.  What travels faster than the speed of light?

3. What’s the link between ordinary Scotch tape” and X-rays?

Tape can generate electromagnetic radiation at terahertz, or X-ray frequencies as you pull the end away from the roll. You can see this phenomenon in action as a glowing line if you do this in the dark – Peeling adhesive tape emits electromagnetic radiation at terahertz frequencies, and Sticky tape generates X-rays.

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