My house came with a satellite dish that I had no intention of using. One day I got sick of looking at it and decided to remove it, but the only free time I could find was late in the evening after work a couple months ago... in the winter... long before Daylight Saving. (I wanted to write this blog then, but it was very late at night, and I forgot about it since.)
In the process, as you might guess from the title, I dropped a screw. Luckily, it didn't pop out with any appreciable initial velocity. Even so, the slope of the roof gave it just enough horizontal movement on the way down to make it difficult to find in the dark grass below.
At first I tried to find it using my phone as a flashlight, but after five minutes combing through grass overdue for a mow, I came up with an idea that I hope others might find useful.
I decided to do a little simulation. I took an identical screw, placed it in roughly the initial location of the lost screw, and released it on purpose. You might think that I ended up with two missing screws instead of one, but the important difference was that I was able to carefully watch the second screw with prepared vigilance and with the phone flashlight. I found the first screw only a few inches away from the second.