Interesting Optical Phenomenon

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Discussion Overview

The discussion revolves around an optical phenomenon observed as lines with a purplish hue reflected from leaves, with participants exploring potential causes and methods for investigation. The scope includes observational analysis and experimental reasoning related to light reflection and alignment.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant notes the lines have a purplish hue and are spaced about 2 feet apart, suggesting a visual observation of an optical effect.
  • Another participant proposes that the phenomenon could be due to the alignment of tree limbs or sunlight reflection from another surface, recommending a method to investigate by moving along the bright spots.
  • A third participant humorously cautions about looking directly at the sun while investigating the lines, suggesting a safer method involving tracing the light source with a hand.
  • A later reply identifies the cause of the effect as reflection from two vertical narrow windows on a neighboring house, supported by a 2D model and a method of tracing light with a black surface.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the initial cause of the optical phenomenon, but one participant later identifies a specific source. The discussion includes multiple viewpoints on how to investigate the phenomenon.

Contextual Notes

The discussion includes assumptions about the alignment of objects and the nature of light reflection, which may not be fully explored or defined. The methods suggested for investigation depend on the observer's perspective and environmental conditions.

bob012345
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TL;DR
Light coming through tree branches makes two bright lines on the ground. Please help me identify what is happening. Thanks.
The lines have a slight purplish hue to them (at least reflected from leaves) and are about 2 feet apart. Here are images of the lines and the sun through the tree.

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I'd guess it's either caused by the way the tree limbs are aligned with each other, or by reflection of sunlight off of another surface. Get down on the ground and stick your eye in one of the bright spots and then move back and forth along it. You should find out very quickly what's causing them.
 
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Drakkith said:
stick your eye in one of the bright spots
...carefully, because that's the Sun you're looking at. Putting your hand on one of the lines and back-tracing the light by moving your hand away while keeping its shadow on the line might be safer.
 
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I discovered what this effect is caused by. As @Drakkith suggested it's simple reflection from two vertical narrow windows on my next door neighbor's house. Here is a 2D model (looking down from above) although the sun is of course also at a vertical angle which explains why the lines have only a certain length on the ground. I discovered this by using a black surface to trace where the light originated from. Science!

Screen Shot 2022-12-15 at 4.34.12 PM.png
 
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