So I'm watching the Hitchhiker's Guide to the Galaxy movie (pity me)! and the destruction of Earth comes up. You can see it here
Although the film sucks, I always loved this sequence. The destruction of Earth is gorgeous, the combination of the massive fleet being given this absurdly over the top treatment by the camera and music as they pull back... back... back... back... back... and then, finally, leading to a detonation that is comically anticlimactic. Plus, it leads into the introduction of the Guide itself, floating in space to that haunting music. Love, love, love this sequence. Which just makes it all the more disappointing that the majority of the film just sucks so badly.
Anyway, the Vogon constructor fleet always intrigued me, so I decided to do a little analysis of these ships, just for fun. Here's a still from the shot where the camera backs out away from the surface, showing the fleet hovering around the Earth :
As you can see, the show shows southern England and the Northern coast of France. The ships are at various heights, but it's clear from the video clip above that the lower ones are quite close to the surface - the jumps in altitude show the lower end of a ship coming into view whilst surface features a few miles apart are visible, so the lower end of the ships are likely no higher up than 20,000 feet or so. One could argue for higher altitudes, and so smaller ships, but there really is only so far you can go with that - see later discussion for details.
I picked out two recognisable spots, one on the coast East of Cherbourg and one on the coast West of Calais. On the screen grab I took, the distance between these two points is 356.51 pixels.
Then I used Google Earth to measure the distance and found that these two spots are 248 kilometres apart. That establishes a scale for these images of 1 pixel = 695 metres.
To minimise errors of perspective and foreshortening angles, I picked out a few ships that appeared to be amongst the lowest, whilst still being relatively close to the centre of the screen, and measured them. I found an average length on a side of 12-14 pixels. Going with the lower end of this, that makes the ships 9.7 kilometres on a side.
Length is more difficult; we're looking at most of these things almost top-down. But it's clear that their length is several times their height; I estimate at least a 4:1 ratio between length and height, indicating a length of 38 kilometres.
Examining a later frame, we see this view :
This is a shot that shows the majority of the planet in one frame. The fact that the ships are even still visible at all, and as more than dimensionless points at that, confirms that the earlier figures were not simply due to errors in perspective. There is certainly a degree of uncertainty, but it's clear from this image that these ships are at least as large as suggested.
Now consider how many ships are in the fleet. The image shows the ships regularly spaced around the planet in a geodesic sphere pattern. It's hard to say how many there are with any degree of precision, but referring back to the earlier images the distance between any two adjacent ships varies between 110 and 200 pixels, putting the ships about 75 - 140 km apart. Taking the midpoint of this as the average, this would mean a ship every 107 km, or about 1 ship every 11,556 km^2 of surface. Given a 510,000,000 km^2 surface, that would equate to 44,000 ships.
And bear in mind, this is not some grand battle fleet come to wage war. This is the galactic equivalent of a construction crew come to knock a house down and put a road through - it intentionally parallels the crew who come to knock Arthur's house down at the start of the film. And personally, I think something like this is actually a more plausible scenario than the alien warfleet; humanity does not wage war on deer or wolves, we don't send out tanks and infantry to try and wipe them out. In terms of purposeful aggression, at most the deer and wolf face individual hunters who are killing them essentially for fun, rather like the Predator in those movies. But the real
threat they face is not purposeful aggression - it's the farmer who wants them away from his crops, it's the construction crews who want to build a new road or a new suburb. Those are the people who come in and devastate the entire area, and the animals are just in the way.
Not that I regard that as being a likely scenario, mind. It's just more likely than an alien war.
Give a man a fire, and you keep him warm for a day. SET a man on fire, and you will keep him warm for the rest of his life...