You know I wander around the intertubes, right? Who doesn’t? Anyway, I saw this collection of strange google Earth images. Yeah, it is kind of dumb, but this one made me think:

That article said the image was from TechEBlog, so there is that.

I have no idea what this thing is, but it is clearly tall. How tall? Instead of searching online for info about this structure (that wouldn’t be any fun), I figured I could do a quick analysis of the shadow. Here we go. First, I need to make some measurements. It turns out that Tracker Video tool for analysis is also quite excellent to use for image analysis.

Before I look at the image, let me draw a diagram of two objects with shadows.

Both of these objects cast shadows. But, there are two important ideas. First, the Sun is so far away that the shadows cast from the objects are at the same angle ( θ ). These shadows make triangle shapes with the ground. Both objects are vertical which means that the triangles are right-triangles. Since they have two of the same angles, the triangles are similar. The ratio of height to length of the shadow is the same for both objects.

The plan is to measure the lengths of the two shadows and estimate the height of the building. This way I can solve for the height of the unknown object as:

And here are my measurements – note that I don’t really need to set a scale for the picture. The key is that I need the ratio of the lengths of shadows. Here is the building – I am setting the length of its shadow as 1 unit.

This gives a shadow length ratio of about 10 to 1. The UFO thingy is 10 times taller than the house structure. I am guessing that is some type of single story structure (just a guess) with a height of around 10 feet. This would make the UFO 100 feet tall.