Life in the Fast Lane

Welcome back!

Never believe what you hear, and only half of what you see — something my father used to always say. This weekend will be one of those occasions where you will not be able to trust your very own eyes.

Photo Shay Stephens. A time-lapse sequence of the moon rising over Seattle. To the camera, the moon appears to be the same size no matter what its location on the sky.

This weekend’s full moon will hang lower in the sky than any other full moon in 2007. When it’s low on the horizon, the moon can appear to be unnaturally larger than when it’s higher in the sky. Scientists tell us that it’s all an optical illusion, namely, the Moon Illusion. Cameras cannot capture what our eyes will be telling us.

What makes the moon so low? The sun and full moon lie on opposite sides of the sky, with a similar effect to a see-saw — when one is high, the other is low. Due to the summer solstice last week (June 21st), the sun is near its highest point in northern skies. The full moon is correspondingly low.

When you look at the moon, rays of moonlight converge and form an image about 0.15 millimeters wide in the back of your eye. High moons and low moons make the same sized spot. Why does your brain think one is larger than the other? Scientists still can’t explain it, reports Science @ Nasa.

In 1913, Mario Ponzo, drew two identical bars across a pair of converging lines, such as depicted to the right. The upper yellow bar looks wider because it spans a greater apparent distance between the rails — the ‘Ponzo Illusion.’ Image – Tony Phillips.

Some researchers believe that the Moon Illusion is Ponzo’s Illusion, with trees and houses playing the role of Ponzo’s converging lines. Foreground objects trick your brain into thinking the moon is larger than it actually is.

But airline pilots flying at very high altitudes sometimes experience the Moon Illusion without any objects in the foreground. What tricks their eyes?

Perhaps the shape of the sky. Humans perceive the sky as a flattened dome, with the zenith nearby and the horizon far away. Birds flying overhead appear closer than birds on the horizon. When the moon is near the horizon, your brain, trained by watching birds, clouds and planes, miscalculates the moon’s true distance and size.

Below: The ‘flattened sky’ model for the Moon Illusion.

Other explanations also exist, but what matters is the illusion itself. The optimum time to view is around moonrise, when the moon is peeking through trees and houses or the landscape, doing its finest for trick you.

Try this experiment — make a tube from rolled up paper so the opening is just slightly larger than the moon when it rises. Tape the tube so the size stays fixed, then check later to see if the moon has changed sizes. Can you see any difference?

Related stories:
Lunar Behavior during Full Moons
Who Owns the Moon & Planets of our Universe?

Random Posts

• Two Amazing New Species of Flying Lemurs Discovered
• Intriguing and Bizarre Art of Bubbles in Photography and Nature
• Playing with Food – Vegetables Transformed into Art Masterpieces
• Legendary and Mysterious Art of Snake Charming Revealed
• Amazing Ice Hotel Quebec – Hotel de Glace
• 27 Worlds Most Amazing Mosques – Part 1
• Crop Circles – Mystery Unraveled
• Stunning Smithsonian Ocean Hall Sea Sights
• The Whopping Colossal Dollars and History Behind Facebook – Infographic
• Most Dangerous Natural Infinity Pool on Earth